Most of these files are assigned to U.S. Precision Lens (USPL), which, as an independent manufacturer of TV projection lenses, filed many patents.  It later became part of Corning, then 3M.  Projector lenses are often good starting points for telecentric designs; I find the USPL designs to be less helpful because of their heavy use of aspheres.

I’ve uploaded several files today:

- Twelve designs for conference room projectors.  I’ve found these designs to be useful reference points for telecentric systems.  The designs generally have a little zoom, with surprisingly complex motion of the elements through zoom.

- Five cinematography projectors.  Image quality is excellent; and, as with most cinematography lenses, color correction is excellent.  Notice that one design is anamorphic.

- Two projectors for photolithography.  Most patented photolith systems are so complex that they don’t seem too instructive.  An obvious exception to this is the original patent for the Offner relay system, a 1:1 projector using just two mirrors.

- Four designs of overhead projectors.  None of the models is typical, in that all four elements instead of the typical three.  One has an unusually large field of view, enabling projection without keystone distortion.  I’m surprised by the relatively poor image quality, although the poor imaging could be due to inaccuracies in the published design example rather than the design capability.

 

Two of these projector models are based on patents from important court cases regarding lens design.  U.S. Patent #3,126,786 was the subject of 3M vs. Projection Optics, and U.S. Patent 3,748,015 was the subject of PerkinElmer vs. ComputerVision.  Both court cases covered tricky issues on obviousness and prior art regarding lens design; Joseph Gortych wrote an excellent review of this issue in Optics and Photonics News, titled “Lens Design Patents: The view from court space.”

Do you see something interesting in these files?  Share your insight in the Comments section.  Do you have lens design files you’d like to share?  Please participate in building the site.