The Glass


The lenses are the heart of the microscope. The refracting of light as it passes through these little shaped pieces of glass is what allows us to see worlds that we can never fit into ourselves. I want to figure out how to make these little inner space travel portals.

I placed a soft black velvet sheet on a table and carefully unscrewed the lens holders of the Bancks 1825 microscope individually. I used a plastic vernier caliper to measure the diamenter (W) and the thickness (2H) of the lenses. All of the Bancks lenses came down, almost, to a pointed edge, the edge was just slightly ground flat or cylidrical. So with the diameter and the thinkness I could calculate the approximate radius of the spherical surface of the lenses using the formula below.
Lens Assembly

 
Lens # H W R
1 - - -
2 1 4.7 3.26
3 0.75 5.5 5.42
4 0.65 6.4 8.20
5 0.65 7.3 10.57
6 0.65 10.3 20.72
  Radius Graphic

 

So now I am working on a way to make some similar lenses. I have found a few sites on the web with articles about making small lenses, and I am working on a modification of the processes descibed on these sites.

Making a Van Leeuwenhoek Microscope Lens
by Hans Loncke, the Netherlands
http://www.microscopy-uk.org.uk/mag//artapr07/hl-scope.html

The Challenge of Grinding Lenses For Single Lens Microscopes
By: Alvaro Amaro de Azevedo, Brazil
http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjan06/aalens2.html

As mentioned earlier, when I purchased my Bancks 1825 microscope, it was missing the glass in the #1 lens. So I do not have the measurements for this lens. :(

Now that I have the approximate curvature of the lenes, I purchased a bunch of steel bearings with similar curvatures. I have some aluminium and some nice drill bits, set screws and taps, so I am looking for a drill press for the next step.

PDF of lens cross sections

Nice web page explaining the derivation of the radius equation above: http://www.mathopenref.com/arcradius.html