US3771879A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process and apparatus for measuring transparency
Assignee: PETROLES AQUITAINE SOC
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Filing: 1971-11-16
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Granted: 1973-11-13
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Expires: 1991-11-16
Abstract
Abstract Existing processes for testing the transparency of various materials involve observing patterns formed of series of black lines on a white background, through a sample of the material concerned. The present invention consists of lighting tee sample with a parallel light beam from collimator, receiving the beam transmitted by the sample on an optical system which is coaxial wth the collimator and forming an image of the slit in the collimator on a sinusoidal pattern which is moving in relation to the collimator, measuring the luminous flux transmitted by the pattern, and working out the factor of contrast, from the maximum and minimum flux transmitted.
Inventors
- 👤 C Chambu
- 👤 J Collo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:38
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/59; G06; G06G; G06G7/00; G06G7/12; G06G7/16; G06G7/25
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
145 words
A process for measuring the transparency of a thin flat sample of material which process comprises the steps of directing a collimated beam of light from a slit through said sample, forming an image of said slit on a pattern whose transmission varies in a sinusoidal manner in a direction transversely of said beam, after said beam has passed through said sample, while moving said pattern in said direction transversely of said beam, receiving the light from said beam which passes through said pattern on a photo-cell to provide a sinusoidal output signal having an amplitude dependent on the quantity of said light being received, and processing said output signal to derive a factor of contrast proportional to (M-m)/(M+m) , where M represents the maximum amplitude and m the minimum amplitude of said sinusoidal output, which factor is representative of the transparency of said sample.
Claim 2
Dependent Claim
145 words
A process for measuring the transparency of a thin flat sample of material which process comprises the steps of directing a collimated beam of light from a slit through said sample, forming an image of said slit on a pattern whose transmission varies in a sinusoidal manner in a direction transversely of said beam, after said beam has passed through said sample, while moving said pattern in said direction transversely of said beam, receiving the light from said beam which passes through said pattern on a photo-cell to provide a sinusoidal output signal having an amplitude dependent on the quantity of said light being received, and processing said output signal to derive a factor of contrast proportional to (M-m)/(M+m) , where M represents the maximum amplitude and m the minimum amplitude of said sinusoidal output, which factor is representative of the transparency of said sample.
Claim 3
Dependent Claim
63 words
A process according to claim 1 comprising measuring the mean light flux of said beam transmitted by the pattern in the presence of the sample and without any sample interposed, and deriving the ratio of the mean light flux transmitted in the presence of the sample to the mean light flux transmitted without any sample interposed to define the transmittance of the sample.
Claim 4
Dependent Claim
23 words
A process according to claim 1, in which the sample is submerged in a liquid with the same refractive index as said sample.
Claim 5
Dependent Claim
25 words
A process according to claim 1, in which the axis of symmetry of the sinusoidal pattern is at right angles to the said optical axis.
Claim 6
Dependent Claim
14 words
A process according to claim 1, in which the pattern has several spatial frequencies.
Claim 7
Dependent Claim
23 words
A process as claimed in claim 1 in which said sample is rotated in a plane transverse to the axis of said beam.
Claim 8
Dependent Claim
25 words
A process as claimed in claim 1 in which said sample is translated in a plane at right angles to the axis of said beam.
Claim 9
Dependent Claim
22 words
A process as claimed in claim 1 in which said sample is selected from the group consisting of liquids, glass, and plastic.
Claim 10
Independent Claim
172 words
An apparatus for measuring the transparency of a sample of material, said apparatus comprising: a sample holder, a collimator provided with a slit and positioned to project a beam of parallel light from said slit into a sample in said Holder, a movable light-transmitting pattern whose transmission varies in a sinusoidal manner in a direction transversely of said beam, means for moving said pattern in said transverse direction, an optical system positioned to form an image of said slit from the light of said beam which has passed through said sample onto said pattern, a photo-receiver positioned to receive the light from said beam which passes through said pattern, and provide a sinusoidal output signal having an amplitude which is dependent on the quantity of said light being received, and means for processing said output signal to derive a factor of contrast proportional to (M-m)/(M+ m) , where M represents the maximum amplitude and m the minimum amplitude of said sinusoidal output, which factor is representative of the transparency of said sample.
Claim 11
Independent Claim
172 words
An apparatus for measuring the transparency of a sample of material, said apparatus comprising: a sample holder, a collimator provided with a slit and positioned to project a beam of parallel light from said slit into a sample in said Holder, a movable light-transmitting pattern whose transmission varies in a sinusoidal manner in a direction transversely of said beam, means for moving said pattern in said transverse direction, an optical system positioned to form an image of said slit from the light of said beam which has passed through said sample onto said pattern, a photo-receiver positioned to receive the light from said beam which passes through said pattern, and provide a sinusoidal output signal having an amplitude which is dependent on the quantity of said light being received, and means for processing said output signal to derive a factor of contrast proportional to (M-m)/(M+ m) , where M represents the maximum amplitude and m the minimum amplitude of said sinusoidal output, which factor is representative of the transparency of said sample.
Claim 12
Dependent Claim
37 words
An apparatus as claimed in claim 9 in which said sample holder contains a recess and said apparatus comprises means to rotate said holder and recess about an axis parallel to the optical axis of said beam.
Claim 13
Dependent Claim
33 words
An apparatus according to claim 10, in which the recess provided in the sample-holder to carry the sample is airtight, and contains a liquid with the same refractive index as the said sample.
Claim 14
Dependent Claim
51 words
An apparatus according to claim 9 in which said photoreceiver is a photo-diode and said processing means contains an amplifier combined with an analogue computer to derive the factor of contrast, said computer being connected to a display unit to transmit a signal indicative of said factor to said display unit.
Claim 15
Dependent Claim
13 words
An apparatus according to claim 9, in which the photo-receiver comprises a photomultiplier.
Claim 16
Dependent Claim
150 words
An apparatus according to claim 9 in which said processing means comprises: a first storage device receiving said input signal and supplying an output signal representing the maximum M of said signal, a second storage device receiving both said input signal and the output signal from the first storage device and supplying an output signal representing the difference (M-m) between the maximum and minimum of said input signal, an amplifier connected to double the output from said first storage device, a differential amplifier connected to receive both the output of said doubling amplifier and that of said second storage device, and to produce a difference signal equal to the difference therebetween, and an analog divider connected to receive both said difference signal and the output of said second storage device, and to produce an output signal equal to the quotient of the signals received thereby which represents the ratio (M-m)/(M+m).
Claim 17
Dependent Claim
51 words
An apparatus as claimed in claim 14 in which each storage system comprises a first differential amplifier connected to load a capacity through a diode controlled by a high-impedance follower differential amplifier, and in which the output of said follower amplifier is connected to the input of said first differential amplifier.
Claim 18
Dependent Claim
18 words
An apparatus as claimed in claim 15 which comprises synchronization means for reducing the stored voltage to zero.
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) | 1976-11-12 | 1977-05-14 | 1977-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-12 | 1981-05-14 | 1981-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-12 | 1985-05-14 | 1985-11-13 | $7700.00 | Window Closed / Lapsed |