1. Applications not suitable for coaxial illumination:

(1) Diffuse reflective objects (paper, resin, painted products, etc.)

Observing with coaxial illumination results in loss of color and creates images with no contrast.

●Business card

(2) Objects with gloss but uneven surfaces

Only the flat portions of the object will shine, while other areas will appear as images without contrast.

●Wire

●Screw

2. Suitable applications for coaxial illumination:

Coaxial illumination is suitable for objects with gloss and flat surfaces.

It is suitable for the following examples:

●Metal plating

●Silicon wafer

●Substrate gold electrodes

Depending on the object, some are suitable for coaxial illumination, while others are more appropriate for ring illumination.

However, ring illumination is more versatile.

Coaxial illumination can only be used for objects that are “glossy” and “flat.”

■Features of Coaxial Illumination

Coaxial illumination is a suitable method for objects with specular reflection (glossy surfaces).

When oblique light, such as from ring illumination, is directed at a specular object, it reflects at the same angle as the incident angle, preventing light from returning to the lens and resulting in a dark image.

However, coaxial illumination is not suitable for glossy objects with uneven surfaces or curvature.

When used on diffusive reflective objects, coaxial illumination causes only the central part to become bright (hotspot), resulting in a foggy image without color contrast.

サンプル1　　　基板の金メッキ部分

The illumination method of a metallurgical microscope (coaxial illumination) is designed for nearly mirror-like, flat objects.

The appearance can significantly differ compared to conventional illumination (ring illumination).

サンプル2　　　1円玉

White and black completely invert.

(The closer the surface is to a mirror finish, the more pronounced this effect becomes.)

サンプル3　　銀メッキのコイン

A silver-plated coin, like the one in the above photo, can be observed with both coaxial and ring illumination.

(Since it is not a perfect specular reflector, both methods are suitable.)

Sample 4: 10-yen coin (diffuse reflector)

A 10-yen coin cannot be observed with coaxial illumination.

Sample 5: Circuit board (observation of diffuse reflector)

Diffuse reflectors cannot be observed with coaxial illumination.

Sample 6: Observation of specular reflectors

Perfect specular reflectors (those close to mirror surfaces) cannot be observed with ring illumination.

Sample 7: Nickel processed product

When using coaxial illumination, please note that diffuse objects cannot be observed.

(Even with metals, black anodizing or paint may be better observed with ring illumination.)

Sample 8: Paper (printed material)

Sample 9: Other objects unsuitable for coaxial illumination

**Ring Illumination**

This provides the most natural appearance, closely resembling the view perceived by the human eye.

For more details on ring illumination, please refer to the following:

**Coaxial Illumination**

When observing reflective objects (such as metals), black and white may reverse depending on the conditions.

For more details on coaxial illumination, please refer to the following:

**Low-Angle Illumination**

Edges appear sharper and more pronounced, resulting in a dark-field-like appearance. (Refer to “Dark-Field Observation” for more information.)

For more details on low-angle illumination, please refer to the following:

The equation is correct: E(θ)=E0(cos⁡θ)4E(\theta) = E_0 (\cos \theta)^4E(θ)=E0​(cosθ)4.

As you move away from the center, the illuminance drops steeply:

• At 30°, it decreases to approximately half (12\frac{1}{2}21​).
• At 45°, it decreases to approximately one-fourth (14\frac{1}{4}41​).

In practical lighting scenarios, the diffusion (or conversely, directionality) of light sources varies, resulting in diverse beam characteristics that may not perfectly align with theoretical values. However, they serve as rough guidelines.

To achieve uniform illumination over a certain area, efforts are made to utilize the central region (the “redder” area) as much as possible and to flatten out its characteristics as much as feasible. This can be achieved by using lenses, diffusers, or other optical elements.

It’s important to note that with point sources (such as small area illuminations), achieving completely uniform illumination across a large area is generally not possible.

●Lumen (lm）     Lumen is a measurement that indicates “how much light is gathered within a certain range from the light source.” It quantifies the luminous flux within a specified angle of emission, regardless of the measuring surface conditions. For example, when indicating the brightness of lighting fixtures like incandescent bulbs or fluorescent lamps, it represents the total luminous flux emitted in all directions. This measurement is commonly found on lighting devices designed to brighten spaces (such as household lighting). With the shift from incandescent bulbs to LEDs, lumens have become the preferred metric over watts. For instance, a 60W incandescent bulb is roughly equivalent to 800 lumens.
● Lux Lux indicates the brightness of a “specific surface” illuminated by light and varies with the measurement distance. It is commonly used for lighting devices where brightness at a certain distance and on a specific surface (lux) is important. In industrial applications, it is used for devices like ring lighting for microscopes and industrial microscopes. In consumer applications, such as desk lamps used for lighting workspaces, lux is often used to express brightness, which aligns better with the intended purpose.
●The measurement method Lux can be easily measured by placing a lux meter on the surface where you want to measure the illuminance. To measure lumens (total luminous flux emitted in all directions), a sophisticated device called an integrating sphere is required.
	＜An integrating sphere＞

Summary: 

**ルーメン (Lumen)**: Indicates “how much light is gathered within a certain range from the light source.” It quantifies the luminous flux within a specified angle of emission, regardless of the measuring surface conditions.

**ルクス (Lux)**: Indicates the brightness of a “specific surface” illuminated by light and varies with the measurement distance. It is commonly used for lighting devices where brightness at a certain distance and on a specific surface (lux) is important.

These metrics help in understanding and quantifying the brightness and efficiency of lighting sources and devices.

(1) When using the XY table,

Place the transmitted illumination (RD-95) underneath a compact stand.
On top of this, install a glass XY table (TK-100N).
This creates a simple transmitted illumination stand.

(2) When using a rotating XY table,

The size of the rotary table matches that of the transmitted illumination (RD-95).
By removing the observation plate from the rotary table and installing the transmitted illumination (RD-95), you create a simple transmitted light stand.

Of course, when using a rotating XY table, similar to (1), you can place the transmitted illumination underneath the stand. You can also use a glass plate on the rotating table to create a transmitted illumination stand.

		Transmitted illumination stand compatible type TK100-N (Stage: Glass)
		Rotating simple XY table T

Coaxial illumination is a lighting method designed for observing specular reflectors.

(It is not suitable for observing diffuse reflectors.)

When observing diffuse reflectors, hotspots (extremely bright areas) occur.

Furthermore, the effect becomes more pronounced at lower magnifications.

(In the case of diffuse reflectors, ring illumination is recommended.)

■Zレンズの最低倍率（X0.7）で上記３点を観察

Even with glossy ceramics, slight hotspots may persist.

Objects ranging from surfaces reflecting surrounding scenery to specular reflectors are within the appropriate observation range.

■ Methods to Reduce Hotspots

If the camera has HDR (High Dynamic Range) capabilities, there is a method to reduce hotspots by sacrificing color vividness.

(However, generally speaking, for diffuse reflectors, it is recommended to use ring illumination rather than coaxial illumination.)

(HDR set to 0 for observing white paper)

（HDR 3　で白紙観察）

Coaxial illumination is a unique lighting method integrated within the optical path of the lens.
(It is effective for observing silicon wafers, plated surfaces, polished metals, etc., and mirror-like objects.)

The differences in the obtained images can be discerned when comparing coaxial illumination with bright-field illumination (such as ring illumination).

	Below is the image captured when photographing a test pattern chrome-deposited on a transparent glass plate (left photo).
(coaxial illumination)	(ring illumination)

Ring illumination provides a more natural appearance, but coaxial illumination offers higher contrast between the glass and pattern areas due to the chrome deposition’s high reflectivity. Depending on the inspection requirements, coaxial illumination can be advantageous. (In the case mentioned, I believe coaxial illumination would be easier for inspecting scratches or defects on the chrome deposition.)

<When coaxial illumination is effective>
It is primarily used when observing flat surfaces with specular reflection (mirror-like objects) or objects close to specular reflection. It enhances strong contrast due to differences in reflectivity.

– Plated metal surface
(coaxial illumination)	(ring illumination)
– Patterns on silicon wafers
(coaxial illumination)	(ring illumination)
– Electrodes on substrate (gold-plated section)
(coaxial illumination)	(ring illumination)

<Instances where coaxial illumination should not be used>
For highly diffuse objects (such as paper, wood, or resin with sandblasting), there is no difference in surface reflectivity (consistent appearance from all angles). Therefore, coaxial illumination would result in images without contrast. Additionally, due to the object’s complete diffuse (Lambertian) nature, hotspots occur in the image (where the center shines brightly).

– White paper (black text printing)
(coaxial illumination)	(ring illumination)

Falling illumination is a lighting method used in microscopes, digital microscopes, and similar devices. It involves illuminating the specimen from above. There are various shapes and types depending on the mounting method and application, such as ring illumination, twin-arm LED illumination, dome-style illumination, arch-shaped illumination, and coaxial illumination.

	Ring illumination GR10-N
	Twin-arm LED illumination SPF-D2

It is effective to use different types of illumination depending on what you want to observe. When attaching to the lens part, ring-shaped illumination is often used.

Ring illumination is attached to the tip of the lens and used for illumination.

I will help you select the appropriate lighting according to your requirements. Please feel free to contact our technical support for assistance.

1. What is Grain Size?

The mechanical properties of metal materials, such as tensile strength and resistance to compressive shear forces, vary depending on the material, necessitating the use of metals appropriate for specific applications. Additionally, heat treatment alters the metallographic structure and, consequently, its mechanical properties. Therefore, the analysis of grain size is a critical inspection for quality assurance of products.

2. Methods for Measuring Grain Size

The commonly used methods to measure the grain size in metals include:

1. Visual comparison using standard charts and a metal microscope (Comparative Method).
2. Incorporating an eyepiece micrometer into the metal microscope for simultaneous observation and comparison (Comparative Method).
3. Incorporating an eyepiece micrometer into the metal microscope for simultaneous observation and calculation (Line-intercept Method).
4. Using a camera and software for grain size measurement (Counting/Planimetric Method, Line-intercept Method).

These methods allow for the analysis of the crystal grain size in metallographic structures.

3. Automatic measurement of metal grain size using software

With method ④ above, the grain size can be measured automatically using software, increasing efficiency.

金属顕微鏡の詳細はこちら

顕微鏡用USB3.0カメラ（500万画素） HDCT-500DN3

粒子解析ソフトウェア G-S Measure（日鉄テクノロジー株式会社製）

4. Additional Convenient Features of Grain Size Measurement Software: Comparative Method

This is a visual inspection method. A sample, such as a metallographic structure, is placed under a microscope. The process involves simultaneous observation of the sample under the microscope and comparison with a “Grain Size Standard Chart (×100) JIS G 0551” or an “eyepiece micrometer (reticle)” printed with the standard chart. The grain size is determined by matching the closest standard chart.

This software facilitates the calculation of grain size by simply selecting the appropriate standard chart while observing the microscope camera’s live video feed. It allows for the superimposition of the standard chart over the live video feed from the microscope camera, providing a highly convenient and efficient feature.

② Counting / Planimetric Method, Line-intercept Method

The Line-intercept Method involves drawing a test line (pattern) on a captured microscopic image. The grain size is calculated by measuring the average line segment length that crosses through each crystal grain when the pattern intersects with the grains. This technique provides an accurate measure of the grain structure’s dimensions by quantifying the interactions between the line and the microstructure.

**Measurement Display Example: ASTM (Line-intercept Method, Line Length Comparison Method)**

After the measurement, areas where the grain boundaries intersect with the test pattern are highlighted in blue.
*Note: The example image measures an area at a microscope magnification of 100 times, within a 1000×1000 dot range.*

5. Conclusion

If the frequency of grain size measurements is high, utilizing the convenient features of this grain size measurement software for automated measurements is key to reducing labor and enhancing efficiency.

・what is welding?

Welding is defined as the process of joining two metal substrates at their junction using heat, pressure, or other methods, or alternatively, joining them by incorporating filler material under heat or pressure.

The primary methods commonly used for heating in welding include electricity, arc discharge, gas, plasma, and laser techniques.

In this process, the weld bead length formed in the weld (weld deposit) significantly affects the strength of the weld joint.

・Evaluation of welding

The portion of the weld where material has been deposited, indicated by the red arrow in the image, is known as the weld bead.

Depending on the welding conditions, the appearance and dimensions (width, length, height) of this weld bead can vary.

The shape of the weld bead allows for the evaluation of whether the welding was performed correctly and if there are any welding defects.

Common welding defects include:

– Insufficient reinforcement
– Overlap
– Undercut
– Porosity
– Cracks

To evaluate this weld bead, it is necessary to measure its three-dimensional shape.

– Inspection in welding involves specifying dimensions in the weld section. This includes the minimum thickness of the weld bead, known as the “throat thickness,” and dimensions such as the “penetration” and “fusion depth,” which measure from the melted metal peak to the surface of the parent metal.

– For more information on measuring weld penetration, click here.

Among the specified dimensions is the “leg length (kyakuchou),” which extends from the weld root section to the end of the weld bead. This leg length serves as one of the criteria for determining the optimal bead width.

Efficiency in measuring the shape and length of weld bead legs.

To ensure welding quality, it is necessary to inspect the weld bead.

Common inspection methods include:

– Visual comparison with a reference sample
– Comparison using a welding gauge and visual inspection

These methods often require high skill from inspectors and can be time-consuming. Moreover, judgments may vary depending on the individual.

Additionally, using welding-specific gauges for measurements requires multiple measurements at various points, which is inefficient.

<Image of welding gauge measurement>

Utilizing the following product can resolve issues related to measuring weld bead lengths:

Recommended product for weld bead length (bead) measurement:

【Weld Bead Length Handy 3D Scanner CSM-HS10WL】

This product is a 3D handheld scanner that allows instant, non-contact and non-destructive measurement of weld bead cross-sections simply by aiming a laser at the weld area to be measured.

*Note: It cannot measure penetration depth inside the weld or internal blowholes.

No need for rulers or welding gauges; it operates using a non-contact optical cutting method triggered by a switch.

You can scan the 3D shape of the laser irradiation line applied to the weld area and measure the cross-sectional view with high accuracy. This allows for instant, non-destructive measurement of weld bead (leg length) without human error or variability.

～ Features of this device include:

Feature 1: Easy-to-use handheld 3D scanner
– Simply connect to a PC or tablet via USB. Once the welding measurement software built into the device is installed on the PC, it can be operated immediately.
– Being handheld makes it easy to handle, allowing measurement of targets that were previously difficult to measure, including large or heavy objects and narrow spaces.

• 。

Feature 2: Measurement by simply aiming and triggering
– When measuring weld beads, conventional methods require the use of a square or welding-specific gauge. With this device, precise measurement with pinpoint accuracy is possible with a single laser shot.
– Simply aim at the weld bead (weld protrusion), pull the trigger switch, and the measurement is done.
– Comes with a detachable guide rod for convenient adjustment of distance and angle during measurements.
– Easily perform 3D measurements of 12 points including “leg length,” “undercut,” “joint angle,” and “excess buildup” using the optical cutting method.

Feature 3: Instant display and saving of leg length measurement results on PC screen
– Measurement results can be saved as files and the data can be utilized in Excel®.
– Numerical results are displayed simultaneously during measurement, ensuring accurate and error-free records.
– Eliminates the need for handwritten records that can be prone to errors and enhances security against tampering.
– Allows for traceability assurance.

～ Additional Convenient Features ~

Feature 1: Equipped with a standard measurement mode convenient for inspecting weld bead (leg length)

・角R(アール)の計測

・Measurement of butt welding

Feature 2: Displaying camera images, laser cross-sectional views, and measurement results on a single screen

• ・Camera Image:
  Displays the captured video of the section through the camera.

  ・Laser Cross-sectional View:
  Clearly displays measurement results with numerical data and cross-sectional diagrams.

  ・Measurement History:
  Displays numerical results of measurements.

Feature 3: Measurement history can be exported to Excel®.

Feature 4: QR Code Reading

Allows easy linkage of measurement results with target items by scanning QR codes or barcodes. This enables the management of measurement results via QR codes.

Additionally, combining QR codes with cloud services enables visualization and digital transformation (DX) of welding operations.

・Summary

If you want to significantly improve and streamline the challenging task of measuring weld bead shapes accurately,

The 【Weld Bead Length Handy 3D Scanner CSM-HS10WL】is incredibly convenient.

・Eliminates variability in measurements by individuals, ensuring quantitative measurement.
・Capable of reading QR codes and linking with product data.
・Enables instant and accurate 3D shape measurement of objects without contact.
・Visualizes anomalies in weld bead areas using color maps.

1. What is Dendrite Arm Spacing?

Dendrite arm spacing is a measurement method used to evaluate the microstructure of aluminum alloys.

A dendrite refers to a tree-like crystal structure that forms as metal solidifies.

This structure features a primary arm along the main axis and secondary arms that develop laterally, both observed in a branched pattern.

Measuring the distance between the centers of these arms provides an index of dendrite density and morphology.

This measurement is influenced by factors such as the metal’s solidification rate and cooling speed, as well as the distribution of crystalline precipitates.

Measuring dendrite arm spacing has become increasingly important in recent years as it reveals the quality and mechanical properties of castings.

2. Measurement Method of Dendrite Arm Spacing

1. Like typical metallographic observations, it involves preprocessing and can be performed using microscope images.

The main steps of preprocessing are:

1. Cutting
2. Embedding in resin
3. Polishing
4. Mirror finishing
5. Etching with chemicals
6. Rinsing with water
7. Drying with a dryer

→ For more information on preprocessing for metallographic observations, click here.

The preprocessing steps alone require significant effort and time.

Following the preprocessing steps mentioned above, dendrite arm spacing measurement is conducted using microscope or microscopy images.

There are two methods for measuring dendrite arm spacing:

– Secondary Arm Method
– Line Intercept Method

The Secondary Arm Method involves selecting sections where secondary arms are aligned and calculating the average spacing between them.

The Line Intercept Method is used for structures with low directional alignment, such as granular crystals, where it is difficult to select aligned secondary arms. This method involves drawing straight lines across dendrite arm boundaries and calculating the spacing based on the number of intercepts.

Manual measurement of these operations requires considerable effort and time.

Therefore, we will now introduce an efficient method for measuring dendrite arm spacing using the following software.

3. Efficient Method for Measuring Dendrite Arm Spacing Using Software

We introduce an efficient measurement method using the “Image Analysis Software WinROOF Material Option.”

This software can calculate measurement results using the “Secondary Branch Method” mentioned above.

Our microscope cameras are compatible with the “Image Analysis Software WinROOF Material Option,” allowing for measurements within live images.

(Of course, it is also possible to load multiple pre-captured images.)

⇒弊社の顕微鏡用カメラはコチラ

Step 1

Open the interface for dendrite arm spacing measurement and load the image.

It is common to perform this measurement across multiple fields of view (images).

Step 2

On the loaded image, use the mouse to set a “measurement line” (shown in the diagram below, within the yellow frame) at the area where you will measure the arm spacing.

Designate the boundaries of the secondary arms as intersections along the set measurement line.

Step 3

Click on the boundary between the measurement line and the secondary arms to add intersections. (Automatic detection feature for intersections available.)

Step 4

Once intersections are specified for one group of arms, repeat the process by setting measurement lines and specifying intersections for other groups of arms within the field of view.

Real-time measurement information is updated on the screen, allowing you to monitor current dendrite arm spacing values. Switch between images (fields of view) to ensure an adequate number of intersection points are specified.

Additional Information

Measurement results can also be exported to Excel for further analysis and documentation.

4. Conclusion

Specialized inspections like Dendrite Arm Spacing (DAS) measurement often require skilled personnel to conduct visual inspections over extended periods.

By introducing this software,

– Reduction in inspection time due to alleviated inspection burdens
– Standardization of inspections
– Improvement in the repeatability of inspections

These aspects significantly enhance efficiency. Moreover, the software enables smooth generation of evaluation reports, facilitating streamlined result reporting.

The “Hole Inspection Lens PHL178” allows for 360° observation of the inner wall surface. Due to its compact size, the lens can be inserted into and used for inspection of holes with a diameter of φ45mm or greater.

Hole Inspection Lens PHL178

A black rubber sheet was attached to a cylindrical PVC pipe with a diameter of approximately φ100mm, and the inner wall was observed.

(Equipment used: Inner Wall Inspection Microscope PHL200BA)

▼camera setup

Since black rubber tends to absorb light, the image can easily become dark. However, by adjusting the lighting and camera settings, it was possible to observe with sufficient brightness.

Even if the light is insufficient, it can be brightened by modifying the illumination. We experimented by attaching commercially available LED tape lights to the side of the lens.

By using the Matsuden Corporation CS/EG series cameras, which are compact, the entire camera can be inserted into the interior, allowing for 360° observation of the inner wall.

The camera can be inserted into a cylinder with an internal diameter of φ45mm, enabling observation of the inner walls.

By manufacturing a jig for inserting the camera, it is possible to observe the inner walls of deep holes.

The endoscopic series of cameras for borescopes typically involve visual confirmation of the imagery on the main monitor. However, as the main unit outputs video signals (AV terminals), if a monitor with a 4:3 aspect ratio and video terminals is available, one can connect via a video cable to view the imagery on an external monitor.

During this process, visual confirmation of the imagery on the main unit’s monitor becomes unavailable. If one wishes to connect to a PC, converting this AV output to USB signals via a converter like the one described below enables input.

Industrial endoscopes are showcased on the Shodensha product website.

What cameras are necessary for a borescope?

Attaching a camera to a borescope results in diminished brightness. Consequently, cameras with high sensitivity or intense illumination are requisite. While our BA200HD model offers both affordability and high sensitivity, certain conditions of the object or the type of borescope may still result in insufficient brightness even with this model. While using intense illumination is an option, it can be costly.

Recommended feature: “Auto Exposure Master”

Here, we introduce our sophisticated high-definition camera. It combines advanced functionality with high sensitivity, rendering it highly effective in dim conditions, especially when coupled with the “Auto Exposure Master” feature. One drawback is the smaller camera sensor size, at 1/2.8 inches, resulting in a slightly narrower area captured in the imagery. However, this model performs well with borescopes with diameters below φ2.7.

What cameras are necessary for a borescope?

Attaching a camera to a borescope results in diminished brightness. Consequently, cameras with high sensitivity or intense illumination are requisite. While our BA200HD model offers both affordability and high sensitivity, certain conditions of the object or the type of borescope may still result in insufficient brightness even with this model. While using intense illumination is an option, it can be costly.

Recommended feature: “Auto Exposure Master”

Here, we introduce our sophisticated high-definition camera. It combines advanced functionality with high sensitivity, rendering it highly effective in dim conditions, especially when coupled with the “Auto Exposure Master” feature. One drawback is the smaller camera sensor size, at 1/2.8 inches, resulting in a slightly narrower area captured in the imagery. However, this model performs well with borescopes with diameters below φ2.7.

The sensor size of the camera connected to the borescope affects the extent of blurring. Conversely, it approaches the image seen directly by the eye.

The focal length (f-value) of the adapter lens also varies.

Confirmation was conducted using a φ4mm 0° borescope.

■ When using an 18mm focal length adapter lens:

(1) With a camera featuring a 1/1.8-inch imaging sensor:

(2) With a camera featuring a 1/2.5-inch imaging sensor:

■ When using a 35mm focal length adapter lens:

(1) With a camera featuring a 1/1.8-inch imaging sensor:

(2) With a camera featuring a 1/2.5-inch imaging sensor:

The field of view when a camera is connected to a borescope and observed on a monitor changes depending on various factors.

This time, we compared the following three points.

　(1) Borescope diameter (φ4mm and φ2.7mm)
(2) Number of camera inches (1/2 inch and 1/3 inch)
(3) f number of connected lens (mm) (35mm and 27mm)

(1) Comparison of borescope diameter between φ4mm and φ2.7mm
(Fixed camera size to 1/3 inch and lens to 35mm)

■φ4mm		■φ2.7mm

As mentioned above, increasing the diameter of the borescope will increase the field of view on the monitor.

(2) Compare camera inches between 1/3 inch and 1/2 inch

(Borescope φ4mm, lens fixed at 35mm)

■1/3inch		■1/2inch

As mentioned above, reducing the camera sensor size will increase the field of view on the monitor.

(3) Comparison of connected lenses between 35mm and 27mm

(Borescope φ4mm, camera fixed at 1/3 inch)

■35mm		■27mm

As mentioned above, increasing the focal length of the connecting lens will widen the field of view on the monitor.

In addition, our connection lens BA-A1835 allows you to adjust the field of view, so you can further widen the field of view on your monitor.

■■Full-field observation (using 1/2 inch camera)		■During magnified observation (using 1/2 inch camera)

By reducing the camera’s sensor size, it can be expanded to almost cover the entire monitor.

(When using 1/3 inch camera and magnifying observation)

For product details of the camera adapter, please see the product page below.

Basically, it fixes the handy light part and camera part.

 The feasibility of observing the interior of a hole using surface-emitting coaxial illumination depends on the diameter of the hole; larger diameters facilitate more effective observation.

The subject is the hole in a cylindrical metal object.	I utilized surface-emitting coaxial illumination to observe the interior of the hole
	– The coaxial illumination allowed light to penetrate deep into the hole, enabling clear observation of any imperfections or scratches within its depths.
	Surface-emitting coaxial illumination

– Endoscopes and borescopes are also effective methods for observing the interiors of holes.

	– High-function industrial endoscope with a 3.5-inch monitor MIGS300-V551 – Cable lengths of 1 meter and 2 meters are available for selection.
	– Flexible, user-friendly cable with a diameter of 5.5mm. The tip features a slim 4.0mm diameter type. MIGS300-401 (available in 1m and 2m lengths).
	– Borescope BAL-0418L (0°) – Available in 0° (direct view), 30° (side view), 70° (side view), and 90° (side view) types. – The outer diameter of the tube is 4mm.
	– Ultra-slim industrial endoscope – Equipped with a 0.7mm ultra-slim probe, enabling the inspection of precision-engineered components.

For more details about the product, please feel free to contact our technical support. We also accept requests for testing.

– When using a side-viewing (90°) borescope, attention must be given to the focal length.

Utilizing a side-viewing configuration inevitably results in a shorter distance to the wall surfaces (indicated by the red arrow).

– Upon magnifying the tip of the side-viewing borescope, it appears as follows.

• Compared to the direct-viewing type, the side-viewing type has a shorter actual focal distance (indicated by the blue arrow) due to the distance represented by the red arrow.

• In practice, a 4mm diameter side-viewing borescope was employed to observe the sidewalls of holes with diameters of 4.5mm, 6mm, and 7mm.

Even when utilizing the focal adjustment feature of the side lens with a diameter of φ4.5mm, the focal point remains entirely unaligned.

■The focal point barely aligns on the side with a φ6.0mm aperture.

However, discrepancies in product manufacturing may result in misalignment.

■On the side with a φ7mm aperture…

There is ample room for adjustment in the lens’s focal adjustment capability. Even accounting for variations in product quality, the distance remains sufficiently usable.

Observation of the side with aperture diameters smaller than φ6mm is made feasible through the utilization of a macro lens attachment ring.

I observed the side with a φ4.5mm aperture diameter by inserting a 5mm macro lens attachment ring.

■Observation of the side with a φ4.5mm aperture diameter (with the addition of a 5mm macro lens attachment ring)

Even at φ4.5mm (with a distance to the wall of 0.25mm), the focal point aligns.

(The presence of a distance between the lens and the mirror within the borescope allows for focal alignment even at 0.25mm.)

■Observation of the side with a φ6mm aperture diameter (with the addition of a 5mm macro lens attachment ring)

There is still room for further adjustment.

When observing the side with a φ4.5mm aperture diameter using direct (0°) wide-angle viewing, the macro lens attachment ring is unnecessary. (Adjustment is possible within standard specifications.)

■Observation of the side with a φ4.5mm aperture diameter (wide-angle, direct viewing)

The appearance when observed with the standard type of direct viewing is as follows for reference.

Please refer to the following for detailed product information on the “φ4mm side-view borescope” and the “5mm macro lens attachment ring” being used this time.

1．Methods of Lateral Viewing with a Borescope

There are primarily two methods of lateral viewing using a borescope. I will introduce the characteristics of each method.

◆ Utilizing a lateral (90°) viewing borescope

The lateral viewing type of borescope, characterized by an optical path arranged in a single direction, may exhibit uneven brightness across the observed surface due to its directional lighting configuration.

The optical path is arranged unidirectionally.		Imbalance in brightness occurs across the observation surface

Additionally, since the illumination is not ring-shaped but directional, uneven brightness may occur on the screen when observing reflective objects.

◆ Covering a direct-view borescope with a side-view tube (side-view adapter).

– A side-view tube (side-view adapter) is an accessory designed for enabling lateral viewing with a direct-view borescope. Simply fitting it over the tip allows for easy lateral observation.

– Note: The diameter of the side-view tube (side-view adapter) for a φ4mm borescope is φ5.5mm, which makes it slightly thicker.

– Image of a Side-View Tube (Side-View Adapter) Installation

– The advantage of the side-view tube (side-view adapter) is that it can be rotated while attached, allowing for easy observation of a 360° field of view.

– The disadvantage is that the edges of the mirror are visible, preventing the use of the entire field of view.

– Using a direct-view type results in ring-shaped illumination. Additionally, the mirror is more susceptible to the effects of dust and dirt (reflections).。

2． When connecting a camera to a borescope.

– When connecting a camera, the differences in this method significantly impact the results, as cameras generally have a lower dynamic range than the human eye.

– Advantages and Disadvantages of Lateral Viewing Type	– Advantages and Disadvantages of Direct-Viewing Type
– Bright and dark areas occur on the same surface. – In the presence of lateral holes, the walls and bottom surfaces of these holes will be shadowed.	– When observing the same surface, the central area appears bright while the periphery remains dark. – Light also reaches the walls and bottom surfaces of lateral holes. – The edges of the mirror are reflected in the view. – The attachment and removal of the side-view tube allow for both direct and lateral observation.
– However, depending on the reflectivity and shape of the object, the lateral viewing type may provide a clearer view.
＜Lateral Viewing Type＞ ・The observation surface is easier to see.。	＜Direct Viewing Type with Side-View Tube＞ ・Illumination is reflected in the central area.

3. Recommended Camera Feature for Borescope Observation: “WDR (HDR)”

Our company recommends cameras with WDR (HDR) functionality for borescope use.

WDR (HDR) stands for Wide Dynamic Range (High Dynamic Range), a feature that expands the camera’s dynamic range.

Below is an image taken with a camera equipped with WDR functionality connected to a side-view type borescope.

The “Lateral Viewing (90°) Type” and “Direct Viewing Type” borescopes introduced here are available through our company.

For more details, please visit the product pages below.

<SAMPLE>

Given the difficulty in obtaining engine cylinders, we conducted tests using aluminum cans for this study. The dimensions of the aluminum can were φ100mm×H130mm. We inscribed numbers from 1 to 5 on the interior wall and introduced several scratches in various locations.

<CAMERA>

Methods 1 to 5 utilized our company’s full high-definition camera. The details of the camera used can be found here. By standardizing the camera, we were able to conduct a pure comparison of lenses. Additionally, for method 6, we employed an S-mount UVC camera as an additional edition.

1. Method for inspecting the entire circumference of the inner wall in one shot using a wide-bore scope.

1. Wide-bore scope: φ4mm
2. Flat dome-type illumination: DC-30D-127W-CH1
3. Illumination for borescope: LED-3WDB

		Left: Scene of the capture Right: Magnification of the insertion part The borescope can be observed slightly protruding from the entrance of the can. Due to the distance and proximity to the bottom, visibility of scratches near the depths is reduced.
		The borescope was positioned slightly away from the entrance to capture the entire area within a single frame.
		To magnify the view, the borescope was slightly inserted from the entrance and captured.

The operability is rated at ★4 due to the ability to confirm the entire circumference of the inner wall in one shot.

The visibility level of scratches is rated at ★3.

2. Method for inspection using a 90° side-view borescope (φ4mm) (requires rotation of the bore).

1. Borescope: φ4mm, 90° side-view
2. Flat dome-type illumination: DC-30D-127W-CH1
3. Illumination for borescope: LED-3WDB

		Scene of the capture: The borescope is inserted into the can. Rotating the bore is necessary for complete circumference inspection (requires rotating the camera). Additionally, during magnification, the entire top-to-bottom view cannot be observed in a single frame, necessitating vertical movement.
		To ensure the entire height fits within one frame, the borescope was positioned slightly away from the inner wall for the capture.
		To magnify the view, the borescope was brought close to the inner wall for the capture.

Rotating the bore is necessary for inspecting the entire circumference of the inner wall, requiring rotation of the camera itself, resulting in a usability rating of ★2.

The visibility level of scratches is rated at ★4.

3. Method for inspection using a 90° side-view (interchangeable tip) rotatable borescope (φ8mm) (requires rotation of the bore).

1. Rotatable borescope (interchangeable tip): φ8mm, 90° side-view
2. Flat dome-type illumination: DC-30D-127W-CH1
3. Illumination for borescope: LED-3WDB

		Scene of the capture: The borescope is inserted into the can. While rotation of the bore is necessary for complete circumference inspection, the rotatable borescope features an interchangeable tip that allows rotation of the tip tube, eliminating the need for camera rotation.
		The borescope was positioned away from the inner wall for the capture, but capturing the entire top-to-bottom view in one frame proved challenging, necessitating slight vertical movement.
		To magnify the view, the borescope was brought close to the inner wall for the capture.

For inspecting the entire circumference of the inner wall, rotation of the bore is unnecessary with the rotatable borescope. However, vertical movement is required, resulting in a usability rating of ★3.

The visibility level of scratches is rated at ★4.

4. Method for inspecting the entire circumference of the inner wall in one shot using a microscope for observing hole walls.

　1. Microscope for observing hole walls (for diameters ranging from φ20mm to φ120mm): PH200BA-D30

		Left: Scene of the capture Right: Product photograph
The lens is positioned near the entrance (no need to insert into the can), allowing for a complete circumference inspection of the can interior in one shot. Visibility is reasonably good. Since there’s no need to insert the lens portion into the can, the risk of damaging the sample is low.
		To ensure the entire area fits within one frame, the lens was positioned slightly away from the entrance for the capture.
		To magnify the view, the lens was positioned at the very edge of the entrance, but it’s not particularly suited for magnification.

Operability is rated at ★4 due to the ability to confirm the entire circumference of the inner wall in one shot.

The visibility level of scratches is also rated at ★4.

5. Method for inspection using a high-magnification lens with a 90° side-view mirror attached to the tip (requires rotation of the lens).

1. High-magnification lens: FZ lens
2. Custom-made 90° side-view mirror attached to the tip of the lens
3. Custom-made LED illumination for attaching the 90° side-view mirror

		Left: Scene of the capture Right: Magnification of the insertion part The lens is fully inserted into the can for observation.
		Minimum magnification: Approximately 40 times
		Maximum magnification: Approximately 200 times

Mainly focused on magnified observation, the visible area at once is narrow, making it difficult to navigate, resulting in a usability rating of ★1.

The visibility level of scratches is rated at ★5.

However, it’s worth noting that for scratch detection purposes, this method may not be practical, and it’s primarily intended for magnified observation purposes.

6. [Special Edition] Method for inspecting the entire circumference of the inner wall in one shot using an S-mount camera and fisheye lens.

　1. UVC camera
2. Fisheye lens
3. Flat dome-type illumination: DC-30D-127W-CH1

		A fisheye lens is attached to a tube camera with interchangeable lenses. This allows for both direct viewing and side-view observation simultaneously.。
* With a lens diameter of 28mm, unlike borescopes, it cannot observe narrow objects. * Additionally, it is not suitable for deep holes.
		Capturing the image slightly away from the entrance of the can.
		Capturing the image right at the entrance of the can.

Operability is rated at ★4 due to the ability to confirm the entire circumference of the inner wall in one shot.

The visibility level of scratches is rated at ★3.

However, it’s worth noting that the visibility can vary significantly depending on how the lighting is applied, resulting in extreme contrasts between bright and dark areas.

<Summary>

When observing inner walls, it’s essential to select a camera system that aligns with your budget and intended purpose.

Considering usability is also recommended during the evaluation process.

Selecting a camera system based on your specific application. Recommended camera systems:

If you aim to inspect the entire circumference of the inner wall in one shot for scratch detection purposes:

4. Method for inspecting the entire circumference of the inner wall in one shot using a microscope for observing hole walls.

– The PH200BA-D30 microscope for observing hole walls (for diameters ranging from φ20mm to φ120mm) is recommended.

If you desire magnified observation of scratches:

5. Method for inspection using a high-magnification lens with a 90° side-view mirror attached to the tip (requires rotation of the lens) is recommended.

If you want to ensure comprehensive observation without missing any area in the 90° inner wall direction:

3. Method for inspection using a 90° side-view (interchangeable tip) rotatable borescope (φ8mm) (requires rotation of the bore) is recommended.

– The components mentioned, including the interchangeable tip rotatable borescope (φ8mm, 90°), flat dome-type illumination (DC-30D-127W-CH1), and illumination for borescope (LED-3WDB), are recommended.

If you want to observe both the bottom and inner walls with a single device:

1. Method for inspecting the entire circumference of the inner wall in one shot using a wide-angle borescope is recommended.

If price is a primary consideration:

6. [Special Edition] Method for inspecting the entire circumference of the inner wall in one shot using an S-mount camera and fisheye lens is recommended.

I’ve summarized the camera systems that can be used for inspecting engine cylinder walls or can walls. I’ll introduce them with actual images, as well as their respective merits and drawbacks.

●Test conditions

<Sample>

Since engine cylinders are difficult to obtain, we conducted the test using aluminum cans this time.
The size of the aluminum can is φ100mm × H130mm.
We marked numbers 1 to 5 on the inner wall.
We made scratches in several places.

<Camera>

Methods 1 to 5 used our full high-definition camera. ⇒ Camera used here
By using the same camera, we can compare the lenses purely.
*For method 6, we used an S-mount UVC camera as a special edition.

●Inspection Method and Results

1.　Method for inspecting the entire circumference of the inner wall in one shot using a wide bore scope

　①ワイドボアスコープ　φ4mm　ボアスコープ　0°
　②平型ドーム式照明　DC-30D-127W-CH1
　③ボアスコープ用照明　LED-3WDB

		Left: Shooting Scene Right: Insertion Port Enlarged The borescope can be observed slightly away from the entrance of the can. There is a distance, and scratches close to the bottom are less visible.
		The borescope is positioned slightly away from the entrance to capture the entire area in a single frame.
		Position the borescope slightly inside the entrance to capture an enlarged view.

The operability is rated at ★4 since the entire circumference of the inner wall can be checked in one shot.

The visibility level of scratches is rated at ★3.

Method 2: Inspection using a 90° side-view borescope (φ4mm) (Requires bore rotation)

　①ボアスコープ　φ4mm　ボアスコープ　90°

　②平型ドーム式照明　DC-30D-127W-CH1

　③ボアスコープ用照明　LED-3WDB

		Shooting Scene The borescope is inserted into the can. Rotating the bore is necessary to inspect the entire circumference (requires rotating the camera along with the bore). Additionally, when enlarging, the top and bottom cannot be observed in a single frame, requiring vertical movement as well.
		Position the borescope slightly away from the inner wall to capture the entire height in a single frame.
		Bring the borescope close to the inner wall to capture an enlarged view.

If inspecting the entire circumference of the inner wall, bore rotation is necessary, requiring rotation of the camera as well, thus rated at ★2 for operability.

However, the visibility level of scratches is rated at ★4.

３.　Method: Inspection using a 90° side-view (interchangeable tip) swivel borescope (φ8mm) (Requires bore rotation)

　①（先端交換式）くるっとボアスコープ　φ８㎜　90°

　②平型ドーム式照明　DC-30D-127W-CH1

　③ボアスコープ用照明　LED-3WDB

		Shooting Scene The borescope is inserted into the can. To inspect the entire circumference, bore rotation is necessary, but since it’s a swivel borescope, the tip tube can be rotated. (Camera rotation is not required)
		The borescope was positioned away from the inner wall for the shot, but capturing the top and bottom in a single frame is not possible, so some vertical movement is required.
		Bring the borescope close to the inner wall to capture an enlarged view.

If inspecting the entire circumference of the inner wall, a swivel borescope eliminates the need for camera rotation, but vertical movement is necessary, rated at ★3 for operability.

However, the visibility level of scratches is rated at ★4.

４.　Method: Inspecting the entire circumference of the inner wall in one shot using a microscope for observing hole walls

　①穴内壁観察用マイクロスコープ（φ20mm～120mm用） PH200BA-D30

		Left: Shooting Scene Right: Product Photo
The lens is positioned near the entrance (no need to insert into the can) to allow for a one-shot inspection of the entire circumference inside the can. Visibility is reasonably good. Since there’s no need to insert the lens portion into the can, the risk of damaging the sample is low.
		Position the lens slightly away from the entrance to capture the entire area in a single frame.
		Capture the image with the lens positioned right at the entrance, allowing for maximum magnification. However, it’s not particularly suitable for significant magnification.

Operability is rated at ★4 since the entire circumference of the inner wall can be checked in one shot.

The visibility level of scratches is also rated at ★4.

５.　Method: Inspection using a high-magnification lens with a 90° side-view mirror attached to the tip (Requires lens rotation)

1. High-magnification lens: FZ lens
2. Custom-made: 90° side-view mirror attached to the tip of the lens
3. Custom-made: LED illumination for attaching the 90° side-view mirror

		Left: Shooting Scene Right: Insertion Port Enlarged The lens is fully inserted into the can for observation.
		Minimum magnification: Approximately 40x
		Maximum magnification: Approximately 200x

Operability is rated at ★1 because the main focus is on magnification, and the visible area at once is narrow, making it difficult to search.

However, the visibility level of scratches is rated at ★5.

It’s worth noting that while it’s not very practical for scratch detection purposes, it’s primarily intended for magnification observation.

。

６.　[Special Edition] Method for inspecting the entire circumference of the inner wall in one shot using an S-mount camera and fisheye lens

1. UVC camera
2. Fisheye lens
3. Flat dome-type lighting DC-30D-127W-CH1

		Attach a fisheye lens to a tube camera with interchangeable lenses. This allows for side-view observation while maintaining direct viewing.
* Since the lens diameter is 28mm, it cannot observe small-diameter objects like borescopes. It’s also not suitable for deep holes.
		Capture the image with the camera positioned slightly away from the entrance of the can.
		Capture the image with the camera positioned right at the entrance of the can.

Operability is rated at ★4 since the entire circumference of the inner wall can be checked in one shot.

The visibility level of scratches is rated at ★3.

However, the visibility greatly varies depending on how the lighting is applied, resulting in extreme differences between bright and dark areas.

Summary:

When observing inner walls, it’s essential to choose a camera system that fits your budget and purpose.

Considering operability is also recommended during the evaluation process.

Recommended camera systems to choose from based on usage

<If you want to check the entire circumference inside the can in one shot for the purpose of finding scratches>

4. Method for inspecting the entire circumference of the inner wall in one shot using a microscopewith an aperture wall observation function.

① The aperture wall observation microscope (for φ20mm to φ120mm) PH200BA-D30 is the best option.

<If you want to magnify the scratches>

5. Method for inspecting using a high-magnification lens with a 90° side-view mirror attached to the tip (Requires lens rotation) is the best option.

<If you want to ensure absolute visibility of the inner wall direction at 90° without missing anything>

3. Method for inspecting using a 90° side-view (interchangeable tip) swivel borescope (φ8mm) (Requires bore rotation)

① (Interchangeable tip) Swivel borescope φ8mm 90°

② Flat dome-type lighting DC-30D-127W-CH1

③ Borescope lighting LED-3WDB is the best option.

<If you want to observe the bottom and inner walls with one device>

1. Method for inspecting the entire circumference of the inner wall in one shot using a wide-angle borescope is the best option.

<If price is a priority>

6. [Special Edition] Method for inspecting the entire circumference of the inner wall in one shot using an S-mount camera and fisheye lens is the best option.

The closest distance to the object within the in-focus range (observation distance) is called the closest distance.

The closest distance has characteristics depending on the type of endoscope.

1. Endoscope equipped with advanced camera

Since there is a camera at the tip, the optical closest distance is longer.

In the case of our endoscope, the closest distance is 10 mm.
The recommended viewing distance is 10-60mm.

Although it is made by another company, some low-priced models seem to have a closest distance of about 40mm.

2. Borescope

Borescopes and fiberscopes have relatively short closest distances.

This is not a guaranteed value as there are individual variations, but when connecting a camera with our borescope, the closest distance is approximately 5 mm.

		Lens focus tonality can be adjusted, but there are limits. The limit is around 5mm.
		When we checked with our current product, the closest distance was 4.5mm.

◆How to shorten the closest distance

By inserting a close-up ring (5mm), the closest distance can be reduced to about 3mm.

		When using our current product with a close-up ring (5mm), the closest distance was 2.5mm.

The “borescope camera” used this time is available at our company.

Additionally, our Borescope Camera Adapter Lens is equipped with a 5mm close-up ring as standard.

For details, please see the product page below.

For heat-resistant borescopes that exceed 150℃, we cover them with a heat-resistant jacket (custom-made product).

Insert water for cooling and air for tip purge into the heat-resistant jacket.

In other words, a chiller device (low-temperature circulation high-temperature water tank) that circulates cooling water is required.

Set the water cooling outlet of the heat-resistant jacket so that the temperature is approximately 60℃ or less.

We can also propose a chiller device (low-temperature circulation high-temperature water tank) that circulates cooling water.

We will have a detailed meeting with the customer, but the following information is required at a minimum.

① Distance from chiller device → water cooling inlet

②Water cooling outlet → Distance to chiller device

③Height difference between chiller device and borescope mounting position

④ Size of heat-resistant jacket, etc.

Heat resistant borescope

A bore is installed in the observation section (high temperature section), and a camera is connected to the end of the bore for observation.

Without cooling device

	120℃対応ボアスコープ（φ4.0mm） 製品詳細はこちらから   ●Heat-resistant borescope that can handle up to 120℃ ●Enables non-destructive visual inspection of the inside of narrow parts that cannot be directly reached by the human eye. ●Compatible with various types of lighting such as M10 P=1.0 and M10 P=0.5 ●Viewing direction: 0° (direct view), 30° (side view), 70° (side view)
	120℃対応ボアスコープ（φ2.7mm） 製品詳細はこちらから

Please refer to the website for details.

With cooling device

If a cooling device is attached to the borescope, it can handle temperatures up to quite high temperatures.
It can also handle extremely high temperatures exceeding 2000℃.
This can be achieved by covering our borescope with a diameter of 4 mm or more (see our website for details) with a heat-resistant jacket (custom-made).

In the observation section (high-temperature area), a bore is installed, and a camera is connected to the end of the bore for observation.

Without cooling device

	120℃ compatible borescope (φ4.0mm) Click here for product details   ●Heat-resistant borescope that can handle up to 120℃ ●Enables non-destructive visual inspection of the inside of narrow parts that cannot be directly reached by the human eye. ●Compatible with various types of lighting such as M10 P=1.0 and M10 P=0.5 ●Viewing direction: 0° (direct view), 30° (side view), 70° (side view)
	120℃ compatible borescope (φ2.7mm) Click here for product details

Please refer to the website for details.

With cooling device

By attaching a cooling device to the borescope, it can withstand significantly high temperatures. It can even handle ultra-high temperatures exceeding 2000°C. This can be achieved by covering our borescopes with a heat-resistant jacket (custom-made) for borescopes with a diameter of φ4mm or larger (please refer to our website for details).

When using a fixed-focus lens alone, close-up photography is not possible due to its minimum focusing distance.

We have confirmed the conditions necessary to secure a 10mm field of view. (The camera uses a 1/3-inch sensor)

■When using an f=25mm lens

“Focal length approximately 70mm f=25mm lens + 5mm close-up ring”

The field of view is approximately 10mm in the vertical direction

■When using an f=16mm lens

Focal length approximately 35mm f=16mm lens + 5mm close-up ring

The ‘fixed-focus lens’ used in this observation is available from our company.

For more details, please visit the product page below

We have a macro zoom lens with aperture control available at our company.

We’ll compare the differences in appearance due to the aperture

The shooting range is as shown in the above photo, but for a clearer comparison, we will enlarge and compare the red-framed area (including scratches, rough surfaces, and metallic surfaces)

1．Fully open aperture

The image becomes brighter and the resolution increases, but the contrast decreases

2．Stop down a bit

The image achieves a balanced mix of color reproduction, contrast, and resolution.

3．As narrow as possible.

The depth of field becomes deeper, but the resolution decreases

＜Reference＞

If you observe the same field of view with a medium magnification macro zoom lens, it will look like the following

The details of the ‘macro zoom lens with aperture control’ used this time can be found on the following product page.

The silver part of our company’s long-distance lens (rear converter) is removed.

It’s a long-distance lens with a magnification ranging from 4x to 40x when the focal length is 300mm.
※ Magnification is calculated based on a 1/2.5 inch camera, equivalent to a 17-inch monitor.

A 5x rear converter is attached.

However, attaching a 5x rear converter will decrease both brightness and resolution.

Our long-distance lens is equipped with a focusing adjustment function, so you can use it with focal lengths ranging from 200mm to 400mm. When attaching the 5x rear converter, if the focal length is set to 200mm, the magnification will be approximately 150x.