A trivia question, hopefully to be answered by someone who really knows the answer: were the aspheric lens elements in Kodak Disc Cameras (the last lenses in which Rudolf Kingslake had a hand, I believe) glass, or plastic, or hybrid? My memory is they were press-moulded, but made of some sort of optical plastic or resin, although the spherical elements were glass.
Anyone know for sure? IMWTK.
ANSWERS: Kevin Purcell tracked this down, from Geometrical and Instrumental Optics by Daniel Malacara, Academic Press, 1988, p. 94, Chapter 3.4.11, "Aspheric Surfaces in Camera Lenses":
And this from Applied photographic optics: lenses and optical systems for photography, film, video, electronic and digital imaging by Sidney F. Ray, Focal Press 2002, p. 173, Chapter 18.4.4, "Design, manufacture and testing of a lens":
Oren Grad notes that the Wikipedia entry cites an article in the April 1982 Modern Photography magazine as a source. He didn't have that within easy reach, but pulled the 4/82 Popular Photography and found this in an article introducing the disc system:
"The lenses are made out of four separate coated glass elements, including one aspheric element to get the maximum sharpness and minimize lens aberration. As my colleague Norman Goldberg pointed out, the disk camera lens is in effect a high-quality microscope objective."
He says there's also a little comment directly from Norman Goldberg, including the following:
"Kodak's disk-camera lens may be the best ever made for an amateur snapshot camera. It's a 12.5mm ƒ/2.8 all-glass, air-spaced triplet with a field-flattening fourth element. The third surface from the front is aspherical, until now something that was possible in large numbers only when molded from plastic...."
I'd say Kevin gets 8 points and Oren 7, meaning that they only have 7,992 and 7,993 points to go, respectively, and they each win a Porsche!
But seriously, thanks to Kevin and Oren.
P.S. Ctein was right (see the Comments Section).
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Featured Comment by Tim Wilson: "They were all glass, including the aspheric lens. Kodak developed the process of Precision Glass Molding (PGM) which could mold the glass aspheres. While I was not directly involved in the PGM process, my department would often make thousands of the precision glass blanks (nubbins) that went into the machines, especially as the project was just getting started. The PGM process (along with the rest of Kodak's commercial optics fabrication capability) was sold to an investor who formed Rochester Precision Optics, where the PGM process lives today."