Browse Prior Art Database

Lens Testing Apparatus

IP.com Disclosure Number: IPCOM000094505D
Original Publication Date: 1965-Feb-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Deerhake, WJ: AUTHOR [+2]

Abstract

This lens testing device employs metal, movable blade 5 carried by horizontally extending rod 7 which is oscillated by flexure motor 9 in a vertical direction. Pinhole 10 is placed in blade 5 and optical ray 12 is passed through 10 impinging upon lens 14 under test.

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Lens Testing Apparatus

This lens testing device employs metal, movable blade 5 carried by horizontally extending rod 7 which is oscillated by flexure motor 9 in a vertical direction. Pinhole 10 is placed in blade 5 and optical ray 12 is passed through 10 impinging upon lens 14 under test.

Knife-edge 16 is positioned at the focal point of lens 14. Rays from pinhole 10 passing beyond knife-edge 16 are detected by photo-multiplier tube 18.

Blade 5 also carries grating 20 through which a focused point of light 22 passes activating photodiode 24. Lines on grating 20 provide a sinusoidally varying signal having a frequency which is a multiple of the vertical oscillation frequency of blade 5.

Each time blade 5 moves up and down, the beam of light passing through lens 14 is alternately blocked and permitted to pass. While the beam passes the knife edge 16, a large output is produced by tube 18. This is shown by the upper portion of curve 25. When the beam is blocked by knife-edge 16, the output of tube 18 is illustrated by the lower portion of curve 25. The slope of curve 25 is an indication of the resolution of lens 14. The output from photodiode 24, illustrated by waveform 27, can be used as a scale factor to determine the slope of curve
25.

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