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In the design of these lenses, special engineering and manufacturing techniques have been applied, which insure concentricity. The factors contributing most to these goals are:
7. The Optical Centering of the Elements: Special equipment assures a high degree of accuracy in centering before and after cementing.
2. The Alignment of the Elements in Their Cells: The basic geometry of the thick edges, plus thick spacers, and the parallel seats, assure an optical-mechanical self-alignment with remarkable accuracy and without imposing impossible tolerances.
3. The Smooth Fit of the Threads: No threads are generated by taps and dies. Retaining ring threads are chased parallel and square to the bore.
4. The Piloting of Cells and Focusing Mounts: Where higher accuracy is required, pilots and threads are used. The threads only to retain, and the pilots to guide and locate. Operational threads are lapped.
All of this is obtained without a sacrifice to production possibilities. The parts are held to such precision that
there is an absolute minimum of hand fit required, which in turn insures a production in keeping with any normal requirements that could be placed upon us within the realm of reason or economic limits.
Patents have been applied for on all of these lenses. Due to the newness of this development, sufficient time has not elapsed to receive patent office action.
While being currently supplied to the military services, it is felt that this series contains features of value to others and so will be commercially available.
The authors wish to give special commendations to the staffs of both General Scientific Corp. and Bell & Howell Co. for the splendid help in the design, development, testing and production of the Miltar lenses.
Discussion
John D. Hayes (Bausch & Lomb Optical Co.): I'd like to ask the authors how they obtained sealing for humidity around the iris diaphragm slot in the barrel?
Mr. Foote: There is no sealing for humidity. The operational requirements of the lens do not specify that in this particular case.
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September 1952 Journal of the SMPTE Vol. 59