Thursday, August 5, 2010

Digital Microscope

On the Home Shop Machinist forum, Evan posted a nifty microscope he made from a camera lens and a webcam:

Yep, Macro Scope, using ordinary camera lenses in macro mode. I have been taking micrographs by snapping pictures with a digital camera held to the eyepiece of my stereo microscope but isn't easy to achieve good focus and contrast. I decided to build something more suited to the job and easier to use.

It uses a generic 1.3 megapixel web cam. Various camera parts were used as well as a variety of raw materials. The base is flycut recycled HDPE that looks like black granite, the main column is a solid bar of extra hard mystery stainless steel that was .030 out of round to start. Gave a bit of pucker factor when I needed to drill and tap two 4-40 holes in it. The rack and pinon are machined from brass as are the supports for the twin lens adjustment rails. The elevating housing is made from acetal bar stock and the lens height/fine focuser screw is aluminum. It took a week of on/off time to make.

It can be dissassembled into 4 main components without tools in a few seconds. Different lenses may be attached via M 42 pentax screw mount or adapters. Long lenses (telephoto) work best because they give more distance to the subject for a given magnification and back focus distance.

Some sample images:

1: The edge of a broad radiused HSS cutter that I thought looked pretty good. That's why I built this device.

2: The point of a carbide graver that I hand sharpened on a diamond wheel. This is one of my best gravers for brass and it's because the flats are very symmetical.

3: An insert that looks ok to the eye but suddenly started cutting poorly.

4: The same type insert new. Note that the edge isn't very sharp.

To Do list includes an X-Y stage, measuring software overlays and an inserted illuminated back light in the base.

Evan later posted about a modification he made to it, replacing the webcam with an NTSC camera, and mounting a cheap LCD display on it.

I think that one of the inexpensive import granite comparator stands that Enco usually has on sale would work really well to base this on, if the size was right. You'd already have a solid base, and nice column, and fine adjustment mechanism. I think you could probably do a lot of things that you might use an optical comparator for with one of these, at least for simple HSM stuff. It would be easy to overlay a drawing of a gear tooth cutter on an image from this, and see how it compares.