Patent US3932744A successfully refreshed from Google Patents.
US3932744A
Expired / Lapsed
US
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Null balance radiometric apparatus
Assignee: WILLIAMSON CORP
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Filing: 1974-12-06
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Granted: 1976-01-13
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Expires: 1994-12-06
Abstract
Abstract In the radiometric apparatus disclosed herein, radiant energy from a target is chopped before reaching a detector element. The same detector element receives radiation from a light-emitting diode which is periodically energized in synchronism with the chopping, the level of the energization of the light-emitting diode being varied as a function of a feedback signal obtained by synchronously demodulating the detector signal. In this manner, the a.c. component of the detector signal is driven to a null balance, the level of energization of the light-emitting diode at balance being indicative of the level of radiation received from the target.
Inventors
- 👤 Alan S. Anderson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:45
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/52
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
200 words
Radiometric apparatus comprising: a detector element providing a signal which varies as a function of incident radiant energy; an optical system for coupling radiation between a target and said detector element; means for chopping radiation energy between said target and said detector element; means for generating a timing signal which is synchronously related to the chopping of radiation from said target; a light-emitting diode for selectively providing radiation which is also incident on said detector; synchronous detector means controlled by said timing signal for demodulating any a.c. component of the signal provided by said detector element which is synchronous with said chopping thereby to obtain a feedback signal which varies as a function of the relative levels of radiation incident on said detector element during the alternate phases of chopping; and circuit means, controlled by said timing signal and said feedback signal, for periodically energizing said light-emitting diode synchronously with the chopping at an average level of energization which is modulated as a function of the feedback signal thereby to balance the incident radiation levels during the alternate phases of chopping, the level of energization of said light-emitting diode being indicative of the level of radiation received from said target.
Claim 2
Dependent Claim
200 words
Radiometric apparatus comprising: a detector element providing a signal which varies as a function of incident radiant energy; an optical system for coupling radiation between a target and said detector element; means for chopping radiation energy between said target and said detector element; means for generating a timing signal which is synchronously related to the chopping of radiation from said target; a light-emitting diode for selectively providing radiation which is also incident on said detector; synchronous detector means controlled by said timing signal for demodulating any a.c. component of the signal provided by said detector element which is synchronous with said chopping thereby to obtain a feedback signal which varies as a function of the relative levels of radiation incident on said detector element during the alternate phases of chopping; and circuit means, controlled by said timing signal and said feedback signal, for periodically energizing said light-emitting diode synchronously with the chopping at an average level of energization which is modulated as a function of the feedback signal thereby to balance the incident radiation levels during the alternate phases of chopping, the level of energization of said light-emitting diode being indicative of the level of radiation received from said target.
Claim 3
Dependent Claim
39 words
Radiometric apparatus as set forth in claim 1 wherein said chopping means comprises a rotating chopping disk and said timing signal generating means comprises an optical interrupter assembly having an optical path which is also chopped by said disk.
Claim 4
Dependent Claim
29 words
Radiometric apparatus as set forth in claim 1 wherein said synchronous detector means comprises a field-effect transistor operating as a signal gate, under the control of said timing signal.
Claim 5
Dependent Claim
33 words
Radiometric apparatus as set forth in claim 3 wherein said circuit means comprises a field-effect transistor operating as a gate and intermittently energizing said light-emitting diode under the control of said timing signal.
Claim 6
Dependent Claim
36 words
Radiometric apparatus as set forth in claim 1 including means for amplifying the a.c. component of the signal provided by said detector and a.g.c. means for reducing the gain at relatively high levels of incident radiation.
Claim 7
Dependent Claim
36 words
Radiometric apparatus as set forth in claim 1 including a linearizing circuit for generating, from the current applied to said light-emitting diode, a voltage which varies essentially in proportion to changes in the corresponding target temperature.
Claim 8
Dependent Claim
199 words
Radiometric apparatus comprising: a detector element providing a signal which varies as a function of incident radiant energy; an optical system for coupling radiation between a target and said detector element; a rotatable chopping disk interposed in the optical path between said target and said detector element; means for generating a timing signal which is synchronously related to the rotation of said chopping disk; a light-emitting diode for selectively providing radiation which is also incident on said detector following an optical path which does not traverse said chopping disk; synchronous detector means controlled by said timing signal for demodulating any a.c. component of the signal provided by said detector element which is synchronous with said chopping thereby to obtain a feedback signal which varies as a function of the relative levels of radiation incident on said detector element during the alternate phases of chopping; and means for applying said feedback signal to said light-emitting diode through a gating means which is controlled by said timing signal thereby to balance the incident radiation levels during the alternate phases of chopping, the average level of energization of said light-emitting diode being indicative of the level of radiation received from said target.
Claim 9
Dependent Claim
199 words
Radiometric apparatus comprising: a detector element providing a signal which varies as a function of incident radiant energy; an optical system for coupling radiation between a target and said detector element; a rotatable chopping disk interposed in the optical path between said target and said detector element; means for generating a timing signal which is synchronously related to the rotation of said chopping disk; a light-emitting diode for selectively providing radiation which is also incident on said detector following an optical path which does not traverse said chopping disk; synchronous detector means controlled by said timing signal for demodulating any a.c. component of the signal provided by said detector element which is synchronous with said chopping thereby to obtain a feedback signal which varies as a function of the relative levels of radiation incident on said detector element during the alternate phases of chopping; and means for applying said feedback signal to said light-emitting diode through a gating means which is controlled by said timing signal thereby to balance the incident radiation levels during the alternate phases of chopping, the average level of energization of said light-emitting diode being indicative of the level of radiation received from said target.
Claim 10
Dependent Claim
34 words
Radiometric apparatus as set forth in claim 7 wherein said synchronous detector means and said gating means comprise field-effect transistors operated as signal switches, the switch of said transistors being by said timing signal.
Claim 11
Dependent Claim
36 words
Radiometric apparatus as set forth in claim 8 including a linearizing circuit for generating, from the current applied to said light-emitting diode, a voltage which varies essentially in proportion to changes in the corresponding target temperature.
Claim 12
Dependent Claim
36 words
Radiometric apparatus as set forth in claim 9 including means for amplifying the a.c. component of the signal provided by said detector and a.g.c. means for reducing the gain at relatively high levels of incident radiation.
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) | 1979-01-12 | 1979-07-14 | 1980-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-12 | 1983-07-14 | 1984-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-12 | 1987-07-14 | 1988-01-13 | $7700.00 | Window Closed / Lapsed |