Patent US4276472A successfully refreshed from Google Patents.
US4276472A
Expired / Lapsed
US
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Detector for Q-switched laser radiation
Assignee: United States Department of the Army
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Filing: 1979-10-15
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Granted: 1981-06-30
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Expires: 1999-10-15
Abstract
Abstract A detector for detecting radiation from a Q-switched laser. The detector prises a plurality of silicon photo-diodes (10) which develop an output signal when struck by incident radiation from the Q-switched laser. The output of the photo-diodes is connected to a pulse-width discriminator (12) and a pulse-amplitude discriminator (13). The pulse-width discriminator generates an output signal only if the amplitude of the output pulse from the photo-diodes is less than 300 nanoseconds, signifying an input pulse from a Q-switched laser. The pulse-amplitude discriminator develops an output signal only when the photo-diode is saturated, again, indicating radiation from a Q-switched laser. The presence of a signal from either the pulse-width discriminator or the pulse-amplitude discriminator indicates that the incident radiation on the photo-diode was indeed from a Q-switched laser.
Inventors
- 👤 Joseph A. Costantino
- 👤 Jeffrey R. Heberley
- 👤 Jerry Neimark
- 👤 Thomas E. Weiner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 08:18
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/4257
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
165 words
Apparatus for detecting radiation from a Q-switched laser, which comprises: at least one photo-detector for developing a first output signal in response to incident optical radiation; means, connected to said photo-detector, for comparing said first output signal with a known reference potential thereby to generate a second output signal if said first output signal exceeds reference potential; a pulse width discriminator, connected to the output of said comparing means, for generating a third output signal if said second output signal has a duration which is less than a predetermined time interval; a pulse-amplitude discriminator, connected to said comparing means, for generating a fourth output signal if said second output signal exceeds a predetermined amplitude; and means, responsive to either said third or said fourth output signal, for generating a fifth output signal indicative of optical radiation from a Q-switched laser, said fifth output pulse generating means generating a pulse having a duration substantially greater than the duration of the pulse generated by said comparing means.
Claim 2
Dependent Claim
165 words
Apparatus for detecting radiation from a Q-switched laser, which comprises: at least one photo-detector for developing a first output signal in response to incident optical radiation; means, connected to said photo-detector, for comparing said first output signal with a known reference potential thereby to generate a second output signal if said first output signal exceeds reference potential; a pulse width discriminator, connected to the output of said comparing means, for generating a third output signal if said second output signal has a duration which is less than a predetermined time interval; a pulse-amplitude discriminator, connected to said comparing means, for generating a fourth output signal if said second output signal exceeds a predetermined amplitude; and means, responsive to either said third or said fourth output signal, for generating a fifth output signal indicative of optical radiation from a Q-switched laser, said fifth output pulse generating means generating a pulse having a duration substantially greater than the duration of the pulse generated by said comparing means.
Claim 3
Dependent Claim
16 words
The apparatus according to claim 1 wherein said at least one photo-detector comprises a silicon photo-diode.
Claim 4
Dependent Claim
34 words
The apparatus according to claim 2, further comprising: a high-pass, spectral filter for filtering said optical radiation prior to its impingement on said photo-diode; and means for screening said photo-diode from radio frequency interference.
Claim 5
Dependent Claim
99 words
The apparatus according to claim 1 wherein said pulse-width discriminator comprises: a first AND-gate having an input connected to the output of said comparing means; a first one-shot multi-vibrator having a pulse generating duration of less than 300 nanoseconds, the input to said one-shot multi-vibrator being connected to the output of said first AND-gate; and an OR-gate having one input connected to a first output of said first one-shot multi-vibrator and a second input connected to the output of said comparing means, the other input of said first AND-gate being connected to a second output of said one-shot multi-vibrator.
Claim 6
Dependent Claim
65 words
The apparatus according to claim 1 wherein said pulse amplitude discriminator comprises: a second one-shot multi-vibrator having an input connected to the output of said photo-detector; and means, associated with the input of said second one-shot multi-vibrator, for reducing the sensitivity thereof such that said second one-shot multi-vibrator generates an output signal only for an output signal from said photo-detector exceeding a second predetermined threshold.
Claim 7
Dependent Claim
73 words
The apparatus according to claim 5 wherein said means for generating a fifth output signal comprises: a second OR-gate having one input connected to the output of said first OR-gate and a second input connected to a first output of said second one-shot multi-vibrator; a pulse-stretching circuit connected to the output of said second OR-gate; and, a line driver, connected to a first output of said pulse stretcher, for amplifying the output therefrom.
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) | 1984-06-29 | 1984-12-29 | 1985-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-29 | 1988-12-29 | 1989-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-29 | 1992-12-29 | 1993-06-30 | $7700.00 | Window Closed / Lapsed |