Depth of focus of high magnification lens

Let’s measure the depth of focus of our high magnification microscope.

A glass scale of 0.2 mm pitch

I shot it at an angle of 45 °.

In order to get depth if it is inclined by 45 °, multiply 1 / √ 2.

 被写界深度
   
Lens at scale 2
without auxiliary len		 高倍率レンズ
   
高倍率レンズ
0.5 mm x (1 / √ 2) = 0.35 mm if it is judged that the focal point is at 0.5 mm
   
Lens at scale 4
without auxiliary lens		 高倍率レンズ
   
高倍率レンズ
0.3mm x X（1/√2）＝0.21mm if it is judged that the focal point is at 0.3 mm

 

The magnification and depth of focus will be the same even if an auxiliary lens is attached.

If you use 2x auxiliary lens, the depth of focus is 0.21 mm” at “scale 2” as above.