A customer came to The Pilot Group with a zoom lens optical design for cinema projectors. They wanted something that could attach to a projector and work, which they could show to customers as a prototype. I tried to make it look nice on the outside without going into a full industrial design effort.

      We were given information on the type of projector it would be mounting to and all the mechanical tolerances for the optical elements. I took it from there and produced this design. Here is a 5 page drawing   of the base optical flange. As parts started to show up, the real fun began. I spent some lonely nights in the cleanroom bouncing a laser off spinning lens assemblies and watching it trace ellipses on the microscope monitor. Before I was done, those ellipses were smaller than the allowable decentering tolerances.

      There were some optical aberrations when we would test it on a projector or send a point of light through it. It turned out to be bad glass so we asked the customer for certain replacements. Once all the elements were good, it worked great. I'm told that when it was unveiled for the customer in Germany, all the engineers were raving about it.

Details:
-19 optical elements
-Lens mounting tolerances from ±5 to ±20 microns.
-Each lens has a glue thickness matched to the CTE of the glass and the adhesive for zero stress across temperature changes.
-3 lens groups moved with stepper motors instead of the traditional cam.
-Zoom cam profiles built into the motor driving ebedded system software.
-The control board was its own web server and the lens could be focused and zoomed with an i-phone.
-Thermistors in all four lens carriers will customize the zoom motion for any temperature variation.