Edges are examined using a View Solutions GE-5 digital microscope. The power has been increased from 60x to 540x by using a 9x auxiliary lens. Hereís the microscope in its original holder:
To improve the lighting and adapt the microscope for examining blade edges Iíve built a new holder and added light emitting diodes at angles that bring out the best detail at the cutting edge. The light from these LEDs hits the blade at a low angle from each side and from the back. An amber LED shines onto the cutting edge of the blade as shown in this photo:
The blade is held on a jig that can be adjusted to make the face of the bevel perpendicular to the line of sight of the microscope.
For a sense of the scale of the 540x images hereís one that shows the face of a $20 bill and one of the blue fibers that are finer than most human hairs.