Patent US3814520A successfully refreshed from Google Patents.
US3814520A
Expired / Lapsed
US
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Method of, and apparatus for gauging, inspecting or measuring physical properties of objects
Assignee: SIRA INST GB
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Filing: 1971-05-28
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Granted: 1974-06-04
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Expires: 1991-05-28
Abstract
Abstract An apparatus for gauging inspecting or measuring properties of objects and employing a detecting device receiving light from an image of the object which light is influenced in accordance with the property under investigation. The detecting device has an array of photo-electric elements or sensors which are separated by the use of masks or other means into two units each exhibiting a sinusoidal variation in sensitivity to the light received along a particular direction. The sinusoidal variations of the units are mutually displaced by 90 electrical degrees so that the device can produce electrical signals corresponding to the real and imaginary parts of a Fourier transform of the distribution of intensity of light in the image. These signals are processed to extract information about the property under investigation.
Inventors
- 👤 L Baker
- 👤 B Biddles
- 👤 T Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:12
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/08; G01M; G01M11/00; G01M11/02; G01M11/0292
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
109 words
A method of gauging, inspecting or measuring a physical property of an object comprising the steps of providing a detecting device having two units sensitive to electromagnetic radiation and each exhibiting a sinusoidal distribution in radiation sensitivity along a predetermined path with the sinusoidal distribution of one unit being effectively displaced by a quarter of the period thereof in relation to the other unit, forming an image of said object on said detecting device and producing from said detecting device first and second electrical signals indicative, respectively, of the real and imaginary parts of a Fourier transform of the spatial distribution of the intensity of radiation in said image.
Claim 2
Independent Claim
109 words
A method of gauging, inspecting or measuring a physical property of an object comprising the steps of providing a detecting device having two units sensitive to electromagnetic radiation and each exhibiting a sinusoidal distribution in radiation sensitivity along a predetermined path with the sinusoidal distribution of one unit being effectively displaced by a quarter of the period thereof in relation to the other unit, forming an image of said object on said detecting device and producing from said detecting device first and second electrical signals indicative, respectively, of the real and imaginary parts of a Fourier transform of the spatial distribution of the intensity of radiation in said image.
Claim 3
Dependent Claim
30 words
A method according to claim 1, further comprising modulating an A.C. carrier wave with the outputs from the units and processing and demodulating the resultant waveform to produce said signals.
Claim 4
Dependent Claim
24 words
A method according to claim 1, further comprising feeding the outputs from the units into a combination of D.C. amplifiers to produce said signals.
Claim 5
Dependent Claim
20 words
A method according to claim 1, further comprising feeding the outputs from the units to potentiometers to produce said signals.
Claim 6
Dependent Claim
30 words
A method according to claim 1, further comprising charging the units to a high reference voltage and allowing the units to discharge according to the amount of radiation received thereby.
Claim 7
Dependent Claim
90 words
A method according to claim 5, further comprising charging each of two elongate units sensitive to said radiation and constituting part of said detecting device to a high reference voltage simultaneously with an associated one of said two units, allowing said elongate units to discharge according to the amount of radiation received thereby, and feeding the difference in the outputs from each of said two units and its associated elongate unit to a sample and hold means whenever the output from either of said units reaches a low reference voltage.
Claim 8
Dependent Claim
24 words
A method according to claim 1 further comprising applying said first and second electrical signals to the X and Y plates of an oscilloscope.
Claim 9
Dependent Claim
56 words
A method according to claim 1, further comprising modulating each of said signals with a carrier wave, one signal being modulated in a sinusoidal manner and the other signal being modulated in a co-sinusoidal manner, adding said modulated waveforms and demodulating the resultant waveform to produce a voltage proportional to the modulus of the Fourier transform.
Claim 10
Dependent Claim
48 words
A method according to claim 1, further comprising making the period of said sinusoidal distributions equal to the size of the image of a reference object to produce a zero modulus for the associated Fourier transform and gauging other objects by determining the change in modulus produced thereby.
Claim 11
Dependent Claim
22 words
A method according to claim 1, further comprising altering the period of said sinusoidal distribution to cover a range of spatial frequencies.
Claim 12
Dependent Claim
61 words
A method according to claim 1, further comprising forming an image of a reference object scanning the images across the device in the direction of said sinusoidal distribution, deriving a voltage proportional to the modulus of the Fourier transform for each image from the electrical signals associated therewith, and comparing the modulus of one image with that of the other image.
Claim 13
Dependent Claim
38 words
A method according to claim 1, further comprising defining said image with a slit and partially rotating the detecting device relative to the slit until the size of the defined image equals the period of the sinusoidal distribution.
Claim 14
Independent Claim
119 words
An apparatus for gauging, inspecting or measuring some physical property of an object; said apparatus comprising means for forming an image of the object, a detecting device for receiving said image of the object, said device having two units sensitive to electromagnetic radiation, each unit exhibiting a sinusoidal distribution in sensitivity to said radiation along a predetermined path, with the sinusoidal distribution of one unit being effectively displaced by a quarter of the period thereof in relation to the other unit, and means, including said detecting device, for producing separate electrical signals indicative of the real and imaginary parts of a Fourier transform of the distribution of intensity of radiation in said image at at least one spatial frequency.
Claim 15
Independent Claim
119 words
An apparatus for gauging, inspecting or measuring some physical property of an object; said apparatus comprising means for forming an image of the object, a detecting device for receiving said image of the object, said device having two units sensitive to electromagnetic radiation, each unit exhibiting a sinusoidal distribution in sensitivity to said radiation along a predetermined path, with the sinusoidal distribution of one unit being effectively displaced by a quarter of the period thereof in relation to the other unit, and means, including said detecting device, for producing separate electrical signals indicative of the real and imaginary parts of a Fourier transform of the distribution of intensity of radiation in said image at at least one spatial frequency.
Claim 16
Dependent Claim
56 words
An apparatus according to claim 13, further including a first pair of outputs connected to one of said two units and a second pair of outputs connected to the other of said two units and a first potentiometer coupled to said first pair of outputs and a second potentiometer coupled to said second pair of outputs.
Claim 17
Dependent Claim
45 words
An apparatus according to claim 13, wherein the detecting device further includes two additional units each formed from an elongate array of radiation sensitive elements, the output of each of said elongate units being operably connected to the output of one of said two units.
Claim 18
Dependent Claim
46 words
An apparatus according to claim 15, further including first and second potentiometers, the output of each elongate unit being connected to the output of its associated one of two units through one of said potentiometers, said first and second electrical signals being taken from the potentiometers.
Claim 19
Dependent Claim
25 words
An apparatus according to claim 15, wherein a plurality of D.C. amplifiers are provided to combine the outputs from said units and produce said signals.
Claim 20
Dependent Claim
81 words
An apparatus according to claim 15, further comprising means for charging the units to a high reference voltage, the units being thereafter allowed to discharge at a rate dependent upon the radiation received thereby, means for sensing whenever the output from the units reaches a low reference voltage, and means activated by said sensing means for sampling the difference between the outputs of one of the said two units and its associated elongate unit and for storage of the difference value.
Claim 21
Dependent Claim
56 words
An apparatus according to claim 13, further including means for modulating an a.c. carrier wave, means for producing said carrier wave, the outputs from said two units being connected to said modulating means to modulate the a.c. carrier wave and means for processing and demodulating the Resultant waveform to produce said first and second electrical signals.
Claim 22
Dependent Claim
22 words
An apparatus according to claim 13, wherein the detecting device is provided with a planar mask at least defining said two units.
Claim 23
Dependent Claim
25 words
An apparatus according to claim 20, further comprising radiation guides devices to couple radiation from the open areas of the mask to the photoelectric elements.
Claim 24
Dependent Claim
26 words
An apparatus according to claim 13, wherein the detecting device comprises a photo-etched silicon chip and a planar mask to delineate the areas forming the units.
Claim 25
Dependent Claim
25 words
An apparatus according to claim 22, further comprising radiation guides devices to couple radiation from the open areas of the mask to the photoelectric elements.
Claim 26
Dependent Claim
28 words
An apparatus according to claim 13, further comprising an oscilloscope the X and Y plates of said oscilloscope being responsive to said first and second electrical signals, respectively.
Claim 27
Dependent Claim
62 words
An apparatus according to claim 15, further comprising means for modulating each of said signals with a carrier wave, one signal being modulated in a sinusoidal manner and the other signal being modulated in a cosinusoidal manner, means for adding said modulated waveform and means for demodulating the resultant waveform to produce a voltage proportional to the modulus of the Fourier transform.
Claim 28
Dependent Claim
27 words
An apparatus according to claim 13, further comprising operational amplifiers receiving said signals and arranged to produce a voltage proportional to the modulus of the Fourier transform.
Claim 29
Dependent Claim
26 words
An apparatus according to claim 13, further including means for varying the period of the sinusoidal distribution in sensitivity of the units of the detecting device.
Claim 30
Dependent Claim
86 words
An apparatus according to claim 13, wherein there is additionally provided means for forming an image of a reference object on the device, means for scanning the images of the object under investigation and the reference object across the device in the direction of said sinusoidal distribution means for deriving from the signals associated with each image a voltage proportional to the modulus of the Fourier transform of the image, and means for comparing the modulus of one image with the modulus of the other image.
Claim 31
Dependent Claim
21 words
An apparatus according to claim 13, wherein the image forming means includes a source of radiation and one or more lenses.
Claim 32
Dependent Claim
16 words
An apparatus according to claim 29, further comprising means for chopping the radiation from said source.
Claim 33
Dependent Claim
32 words
An apparatus according to claim 13, wherein the image formed by the image-forming means is defined by a slit further including means for partially rotating the detecting device relative to said slit.
Claim 34
Dependent Claim
32 words
An apparatus according to claim 13 further comprising a linear elongate strip of radiation-sensitive elements extending along said predetermined path so as to receive said image and produce a reference signal thereform.
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) | 1977-06-03 | 1977-12-03 | 1978-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-03 | 1981-12-03 | 1982-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-03 | 1985-12-03 | 1986-06-04 | $7700.00 | Window Closed / Lapsed |