US3904294A
Expired / Lapsed
US
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Automatic lens testing apparatus
Assignee: Polaroid Corp
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Filing: 1973-12-28
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Granted: 1975-09-09
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Expires: 1993-12-28
Abstract
Abstract This invention relates to a method and apparatus for acceptance testing of photographic objective lenses. It includes evaluating the lenses'' optical performance at several representative locations in the focal plane. The apparatus incorporates certain features that simplify the signal processing necessary to determine whether a specific objective lens is acceptable or not.
Inventors
- 👤 Nathan Gold
- 👤 William T Plummer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:09
CPC Classifications
G; G01; G01M; G01M11/00; G01M11/02; G01M11/0285
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
124 words
A multiplexed acceptance testing apparatus for evaluating a test lens, said multiplexed acceptance testing apparatus comprising: a test station for releasably positioning said test lens; and a plurality of optical paths multiplexed through said test lens each said optical path having an orientation, relative to the optical axis of said test lens, different from the orientation of each other said optical path, each said optical path including, a light source, a test pattern in the field of view of said test lens, means to illuminate said test pattern with light from said source, and means for sampling an image of said target formed by said test lens and for producing a measureable effect that is a function of said test lens'' contrast transfer efficiency.
Claim 2
Dependent Claim
124 words
A multiplexed acceptance testing apparatus for evaluating a test lens, said multiplexed acceptance testing apparatus comprising: a test station for releasably positioning said test lens; and a plurality of optical paths multiplexed through said test lens each said optical path having an orientation, relative to the optical axis of said test lens, different from the orientation of each other said optical path, each said optical path including, a light source, a test pattern in the field of view of said test lens, means to illuminate said test pattern with light from said source, and means for sampling an image of said target formed by said test lens and for producing a measureable effect that is a function of said test lens'' contrast transfer efficiency.
Claim 3
Dependent Claim
154 words
A multiplexed acceptance testing apparatus for evaluating a test lens, said multiplexed acceptance testing apparatus comprising: a test station for releasably positioning said test lens, said test station including means for adjusting the focus of said test lens and means for generating a signal proportional to the amount of adjustment effected; and a plurality of optical paths multiplexed through said test lens each said optical path having an orientation, relative to the optical axis of said test lens, different from the orientation of each other said optical path, each said optical path including, a light source, a test pattern in the field of view of said test lens, means to illuminate said test pattern with light from said source, and means for sampling an image of said target formed by said test lens and for producing a measurable effect that is a function of said test lens'' contrast transfer efficiency along said optical path.
Claim 4
Dependent Claim
154 words
A multiplexed acceptance testing apparatus for evaluating a test lens, said multiplexed acceptance testing apparatus comprising: a test station for releasably positioning said test lens, said test station including means for adjusting the focus of said test lens and means for generating a signal proportional to the amount of adjustment effected; and a plurality of optical paths multiplexed through said test lens each said optical path having an orientation, relative to the optical axis of said test lens, different from the orientation of each other said optical path, each said optical path including, a light source, a test pattern in the field of view of said test lens, means to illuminate said test pattern with light from said source, and means for sampling an image of said target formed by said test lens and for producing a measurable effect that is a function of said test lens'' contrast transfer efficiency along said optical path.
Claim 5
Dependent Claim
68 words
The multiplexed acceptance testing apparatus described in claim 2 wherein said sampling means includes an opening at the focal plane of said test lens whose Shape corresponds to the shape of the best image a perfect test lens would form at said focal plane of said test pattern and wherein each said optical path further includes a photodetector for receiving light from said image passing through said opening.
Claim 6
Dependent Claim
58 words
The multiplexed acceptance testing apparatus described in claim 3 wherein each optical path further includes: a target lens for establishing a predetermined effective optical path distance between said test pattern and said test lens; and a condensing lens between said opening and said photodetector for promoting the efficient transfer of light passing through said opening to said photodetector.
Claim 7
Dependent Claim
47 words
The multiplexed acceptance testing apparatus described in claim 3 wherein: a single light source serves all of said optical paths by illuminating all of said test patterns; and a single photodetector serves all of said optical paths by receiving the light passing through all of said openings.
Claim 8
Dependent Claim
55 words
The multiplexed acceptance testing apparatus described in claim 3 wherein each said test pattern comprises a plurality of mutually aligned slots separated by intervening opaque spaces, said slots and said opaque spaces being of equal width, and wherein each said opening comprises a slit having a width equal to the width of said best image.
Claim 9
Dependent Claim
39 words
The multiplexed acceptance testing apparatus described in claim 3 further comprising means for affecting each said optical path so each signal component emitted by said photodetector is identifiable as to which said optical path said signal component relates to.
Claim 10
Dependent Claim
44 words
The multiplexed acceptance testing apparatus described in claim 7 further comprising: signal processing means for receiving said signal from said test station and said signals from said photodetector and for evaluating them according to predetermined criteria to determine the acceptability of said test lens.
Claim 11
Dependent Claim
28 words
The multiplexed acceptance testing apparatus described in claim 8 wherein said signal from said test station and said signals from said photodetector reach said signal processing means simultaneously.
Claim 12
Dependent Claim
22 words
The multiplexed acceptance testing apparatus described in claim 3 further comprising: servo means for maintaining the average signal from said photodetector constant.
Claim 13
Dependent Claim
69 words
The multiplexed acceptance testing apparatus described in claim 10, wherein said photodetector is a photomultiplier, further comprising: a variably high voltage power supply for said photomultiplier and wherein said servo means includes an average DC level detector for monitoring the signals emitted by said photomultiplier and for adjusting said variable high voltage supply in accordance therewith so as to maintain the average DC signal level from said photomultiplier constant.
Claim 14
Dependent Claim
108 words
The multiplexed acceptance testing apparatus described in claim 9 wherein said signal processing means includes: a plurality of channel evaluators, each for evaluating a different one of said plurality of optical paths through said test lens, each having a filter for blocking all signals except those identified for its own channel evaluator, an amplitude detector that receives the signal passed by said filter, a threshold signal level comparator to determine if the peak value of the passed signal''s amplitude at least equals a predetermined minimum peak value, and a peak signal level comparator to determine if the amplitude of the passed signal is above a predetermined threshold value.
Claim 15
Dependent Claim
139 words
The multiplexed acceptance testing apparatus described in claim 12 wherein said signal processing means further includes: first ''''and'''' gate means for determining if all of said threshold signal level comparators are detecting signals above said threshold value and for transmitting notification when that is the fact; counter means for receiving said notification and for receiving and evaluating said signal from said test station while said notification continues to be provided; a processor operatively associated with said coUnter means and said first ''''and'''' gate means for determining if the signal from said test station achieves at least a predetermined minimum value during the period said first ''''and'''' gate means is transmitting said notification; and second ''''and'''' gate means for determining and remembering if all of said peak signal level comparators have detected a signal of said predetermined minimum peak value.
Claim 16
Dependent Claim
37 words
The multiplexed acceptance testing apparatus described in claim 13 wherein said signal processing means further includes: means for resetting certain components of said signal processor after it makes its decision about accepting a particular said test lens.
Claim 17
Dependent Claim
24 words
The multiplexed acceptance testing apparatus described in claim 2 wherein said means, at said test station, for generating a signal is a shaft encoder.
Claim 18
Dependent Claim
98 words
The multiplexed acceptance testing apparatus described in claim 7 wherein: each said test pattern consists of a plurality of alternating radial slots and radial spokes of equal dimensions on a rotatable disk; each said opening comprises a slit having a width and a position coinciding with the width and position of said best image; and each said rotatable disk has a tangential velocity at its said radial slots specific to the optical path it affects, whereby each signal component emitted by said photodetector is identifiable, by its temporal frequency, as to which said optical path it pertains to.
Claim 19
Dependent Claim
58 words
The multiplexed acceptance testing apparatus described in claim 4 further comprising: an image plate, proximate the best focal plane of said test lens, including means for movably positioning each said slit relative to the plane of said image plate whereby said slits may be arranged to conform to the residual field shape calculated for said perfect test lens.
Claim 20
Dependent Claim
42 words
The multiplexed acceptance testing apparatus described in claim 2 wherein said plurality of optical paths are arranged in a predetermined relationship so as to sample the performance of said test lens throughout its field of view in both sagittal and tangential directions.
Claim 21
Dependent Claim
66 words
The multiplexed acceptance testing apparatus described in claim 3 wherein said openings are slits and wherein said plurality of optical paths are arranged so said slits lie in at least two concentric rings with alternate slits aligned with respect to the center of the focal plane so as to evaluate tengential image quality and with the intervening slits aligned so as to evaluate sagittal image quality.
Claim 22
Dependent Claim
170 words
A lens testing apparatus comprising: test station means for releasably holding a lens; an image plate situate at the focal plane of said lens held in said test station; means for changing the focus of said lens relative to said image plate; a plurality of test patterns disposed in a predetermined pattern within the field of said lens; a plurality of target slits through said image plate, the arrangement of said plurality of target slits in said image plate corresponding to said predetermined pattern so each target slit receives an image, formed by said lens, of one of said plurality of test patterns; illuminating means for providing to each of said plurality of test patterns light by which said lens can form the images of said plurality of test patterns at said plurality of target slits; and detecting means for monitoring the amount of said light that is transmitted through said target slits and for generating a signal containing information about the amount of light transmitted by each target slit.
Claim 23
Dependent Claim
170 words
A lens testing apparatus comprising: test station means for releasably holding a lens; an image plate situate at the focal plane of said lens held in said test station; means for changing the focus of said lens relative to said image plate; a plurality of test patterns disposed in a predetermined pattern within the field of said lens; a plurality of target slits through said image plate, the arrangement of said plurality of target slits in said image plate corresponding to said predetermined pattern so each target slit receives an image, formed by said lens, of one of said plurality of test patterns; illuminating means for providing to each of said plurality of test patterns light by which said lens can form the images of said plurality of test patterns at said plurality of target slits; and detecting means for monitoring the amount of said light that is transmitted through said target slits and for generating a signal containing information about the amount of light transmitted by each target slit.
Claim 24
Dependent Claim
34 words
The lens testing apparatus described in claim 20 further comprising: signal processing means for separating the information, about the amount of said light each of said plurality of target slits transmits, from said signal.
Claim 25
Dependent Claim
26 words
The lens testing apparatus described in claim 20 further comprising: means for providing a predetermined optical distance between said lens and said plurality of test patterns.
Claim 26
Dependent Claim
21 words
The lens testing apparatus Described in claim 22 wherein said means for providing a predetermined optical distance includes a target lens.
Claim 27
Dependent Claim
68 words
The lens testing apparatus described in claim 20 wherein each of said plurality of test patterns includes: a chopping disk with a plurality of uniform radial slots therein to allow the transmission of light through said chopping disk, each of said uniform radial slots being separated from the next adjacent radial slot in said chopping disk by an opaque spoke approximately equal in width to said radial slot.
Claim 28
Dependent Claim
90 words
The lens testing apparatus described in claim 24 wherein each said target slit has a long dimension and a width equal to the width of the image formed thereon by said lens of said radial slots in one of said chopping disks, and a first group of said target slits through said image plate have their length oriented radially, with respect to the center of said focal plane, and a second group of said target slits have their length oriented tangentially with respect to the center of said focal plane.
Claim 29
Dependent Claim
83 words
The lens testing apparatus described in claim 25 further comprising: an opaque mask proximate said test patterns; a plurality of windows in said opaque mask, each of said windows being substantially smaller than a chopping disk and located in said image plate in association with a particular one of said chopping disks so as to transmit to said focal plane images of said slots in said chopper disks that are approximately parallel to said target slits in said focal plane they fall on.
Claim 30
Dependent Claim
25 words
The lens testing apparatus described in claim 26 wherein the spatial frequency of the slots and spokes of each chopping disk are substantially the same.
Claim 31
Dependent Claim
57 words
The lens testing apparatus described in claim 20 further comprising: means for imparting to said light transmitted through each said target slit a temporal frequency different from the temporal frequency imparted to said light transmitted through each other said target slit, whereby said light can be identified as to which said target slit it was transmitted through.
Claim 32
Dependent Claim
38 words
The lens testing apparatus described in claim 28, wherein said signal includes DC and AC components, further comprising: means for servoing said detecting means so as to maintain a predetermined amount of DC signal from said detecting means.
Claim 33
Dependent Claim
46 words
The lens testing apparatus described in claim 29 wherein said test patterns are pluralities of radial slots on a rotatable chopping disk and said means for imparting different temporal frequencies causes each test pattern to move with a different velocity from each other said test pattern.
Claim 34
Dependent Claim
60 words
The lens testing apparatus described in claim 21 wherein said signal includes DC and AC components, further comprising: logic means for deciding if the AC signal components associated with each said target slit exceed a first predetermined value and correlating that with the depth of focus of said lens for which said AC signal components exceed said first predetermined value.
Claim 35
Dependent Claim
25 words
The lens testing apparatus described in claim 31 further comprising: means for deciding if each of said AC signal components exceeds a second predetermined value.
Claim 36
Independent Claim
171 words
An apparatus for testing lenses, said apparatus comprising: collet means for releasably holding a lens to be tested; a plurality of test targets with a predetermined arrangement in the field of said lens; an image plate at the focal plane of said lens; a plurality of target slits in said image plate, said plurality of target slits arranged to each receive an image, formed by said lens, of one of said plurality of test targets, said lens and said pluralities of test targets and target slits aligned with respect to each other to establish a plurality of different optical paths through said lens; illuminating means; means for illuminating said plurality of test targets with light from said illuminating means; means for collecting the light transmitted through said plurality of targeT slits; and detector means with a photosensitive surface positioned to receive said light collected from said plurality of target slits, for generating a signal containing information about the contrast transfer efficiency of said lens for each said optical path through it.
Claim 37
Independent Claim
171 words
An apparatus for testing lenses, said apparatus comprising: collet means for releasably holding a lens to be tested; a plurality of test targets with a predetermined arrangement in the field of said lens; an image plate at the focal plane of said lens; a plurality of target slits in said image plate, said plurality of target slits arranged to each receive an image, formed by said lens, of one of said plurality of test targets, said lens and said pluralities of test targets and target slits aligned with respect to each other to establish a plurality of different optical paths through said lens; illuminating means; means for illuminating said plurality of test targets with light from said illuminating means; means for collecting the light transmitted through said plurality of targeT slits; and detector means with a photosensitive surface positioned to receive said light collected from said plurality of target slits, for generating a signal containing information about the contrast transfer efficiency of said lens for each said optical path through it.
Claim 38
Dependent Claim
39 words
The apparatus described in claim 33, further comprising: servo means for operationally controlling said detector means so as to maintain a predetermined amount of DC signal from said detecting means despite changes common to all of said optical paths.
Claim 39
Dependent Claim
54 words
The apparatus described in claim 33, further comprising: means for imparting a different characteristic temporal frequency to the light transmitted by each said optical path; and signal processing means for sorting the information generated by said detecting means, about the contrast transfer efficiency of said lens for each said optical path through said lens.
Claim 40
Independent Claim
184 words
An apparatus for testing lenses, said apparatus comprising: collet means for releasably holding a lens to be tested on said apparatus; an image plate situate at the focal plane of said lens; a light source in the field of said lens; detecting means, including a photosensitive surface; a plurality of angularly separated optical paths through said lens, along each of which said light source can transmit light to said photosensitive surface, each of said optical paths including, a chopping disk on the side of said lens toward said light source and a target slit through said image plate, each said chopping disk having a plurality of radial slots, each slot of a width selected so the width of the image of said slot formed by said lens on said image plate equals the width of said slit; means for moving each plurality of radial slots at a velocity that is different from the velocity of each other chopping plurality of radial slots; servo means for operationally controlling said detector means so as to maintain any DC signal from said detector at a predetermined amount.
Claim 41
Independent Claim
184 words
An apparatus for testing lenses, said apparatus comprising: collet means for releasably holding a lens to be tested on said apparatus; an image plate situate at the focal plane of said lens; a light source in the field of said lens; detecting means, including a photosensitive surface; a plurality of angularly separated optical paths through said lens, along each of which said light source can transmit light to said photosensitive surface, each of said optical paths including, a chopping disk on the side of said lens toward said light source and a target slit through said image plate, each said chopping disk having a plurality of radial slots, each slot of a width selected so the width of the image of said slot formed by said lens on said image plate equals the width of said slit; means for moving each plurality of radial slots at a velocity that is different from the velocity of each other chopping plurality of radial slots; servo means for operationally controlling said detector means so as to maintain any DC signal from said detector at a predetermined amount.
Claim 42
Dependent Claim
30 words
The apparatus described in claim 36, further comprising: signal processing means for separating the components of said signal attributable to light transmitted along each of said plurality of optical paths.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-08 | 1979-03-10 | 1979-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-08 | 1983-03-10 | 1983-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-08 | 1987-03-10 | 1987-09-09 | $7700.00 | Window Closed / Lapsed |