High speed optical wavelength detection system

• US 3,929,398 A
• Filed: 08/18/1971
• Issued: 12/30/1975
• Est. Priority Date: 08/18/1971
• Status: Expired due to Term

• Current Assignee: Harry E. Bates
• Original Assignee: Harry E. Bates
• Inventors: Bates, Harry E.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US05/172,797
• Time in Patent Office: 1,595 Days
• Field of Search: 356/74,79,82,173,178,186,195,174,225,226,152,168 340/347P 250/22M,23R,226
• US Class Current: 356/416
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00
• CPC Class Codes: G01J 9/0246 Measuring optical wavelength

Abstract

Light whose wavelength is to be measured is applied to a device utilizing a light processing means which serves to transmit light to a detector array in a manner determined by its wavelength. The coded output of the detector array can thus immediately indicate the wavelength of the incoming light. I prefer to utilize a wedge interference filter to produce a line of light extending across the width of the filter at a position along its length, which position is a function of the wavelength. The position of the line of light is encoded by a binary code mask to digitally indicate the light wavelength. Indicator lamps are activated in accordance with the digital indication and are rendered responsive to the light from the code mask in response to a high sensitivity detector. The system broadly includes apparatus for measuring a light signal in which a plurality of signal transmission paths whose transfer functions are different functions of light wavelength effect transmission of the light signal to a unique combination of the output channels responsive to a specific input wavelength.

Claims

1. Apparatus for providing a virtually instantaneous indication of the wavelength of incoming light, comprising an array of detectors activable by light, said detectors having respective outputs and being disposed in an order arrangement, said detectors revealing by virtue of the order and arrangement of their outputs, a coded indication of the wavelength of the incoming light, and processing means for receiving and transmitting to said detectors, the light whose wavelength is to be measured, said means comprising means for simultaneously and selectively transmitting or blocking light inputs to each of said detectors as a function of the wavelength of the light, thus to enable said detectors to reveal a coded indication of the wavelength of the incoming light. 2. Apparatus for providing a virtually instantaneous indication of the wavelength of incoming light, comprising an array of detectors activable by light, with each detector having a respective output, and Processing means for receiving and tramsmitting to said detectors, the light whose wavelength is to be measured, said means comprising means for simultaneously and selectively transmitting or blocking light inputs to each of said detectors as a function of the wavelength of the light, thus to enable said detectors to reveal by the order and arrangement of their outputs, a coded indication of the wavelength of the incoming light, said processing means comprising an interference wedge filter which passes incoming light as a line of light residing at a location on the filter dependent on the wavelength of the light, and a code mask usable in conjunction with said filter, said code mask serving to encode the position of the line of light and to transmit selected portions thereof to a unique combination of detectors of said detector array.

3. The apparatus as defined in claim 2 in which said interference wedge filter and said code mask are substantially rectangular in configuration.

4. The apparatus as defined in claim 2 in which said interference wedge filter and said code mask are substantially circular in configuration.

5. The apparatus as defined in claim 1 in which a prism spectrometer is used in conjunction with a code mask to form a part of said processing means.

6. The apparatus as defined in claim 1 in which a grating spectrometer is used in conjunction with a code mask to form a part of said processing means.

7. The apparatus as defined in claim 1 in which said processing means takes the form of individual filters for each detector of said array of detectors, each of said filters having its individual wavelength transfer function such that light of a given wavelength is transmitted and detected by a unique combination of detectors.

8. In an apparatus for determining the wavelength of light, detecting means comprising an array of detectors, each of which is activable by light to produce an output, and processing means for receiving and transmitting to said detectors, the light whose wavelength is to be measured, said processing means comprising means for selectively transmitting or blocking light inputs to each of said detectors as a function of the wavelength of the incoming light, thereby to transmit unique combinations of inputs to said detectors for different wavelengths, and thus control the outputs of said detector array so that a virtually instantaneous readout as to the wavelength of the incoming light is provided.

9. In an apparatus as defined in claim 8 wherein said means for selectively transmitting or blocking light comprises means for forming a line of light in response to an input at a position along a path which is a function of the wavelength of the light to be measured, and coding means for selectively transmitting or blocking portions of said line of light to said detectors.

10. An apparatus as defined in claim 9 wherein said coding means comprises a binary mask having a plurality of binary code channels extending perpendicular to said line of light.

11. In an apparatus as defined in claim 9 wherein said means for forming a line of light comprises a wedge interference filter.

12. An apparatus as defined in claim 11 wherein said coding means comprises a binary mask having a plurality of binary code channels extending perpendicular to said line of light.

13. In an apparatus according to claim 8 in which said detectors each have an electrical output which varies in response to the amount of light activating the corresponding detector, said detecting means further comprising a plurality of threshold circuits each connected to the output of a respective one of said detectors to provide a first output signal when the light activating the corresponding detector is above a predetermined level, and a different output signal when the light is less than said predetermined level.

14. In an apparatus according to claim 13 wherein the apparatus further comprises output means responsive to the output signals from said threshold circUits to indicate the conditions of said detectors including circuit means having a first state for preventing said output means from responding to the output signals from said threshold circuits and activable to a second state enabling said output means to respond to said output signals, and light detecting means for detecting the presence of light of the type to be measured for activating said circuit means to its said second state.

15. In an apparatus as defined in claim 8 wherein a plurality of channels are utilized, one channel being associated with each detector, said detecting means comprising a plurality of light guides, one for receiving light from each of said channels, said light guides each comprising a light reflecting element of a configuration to focus light from said channel at a detecting location.

16. In an apparatus as defined in claim 15 wherein said light guides are each spaced polished plates extending perpendicularly to said mask and defining an aperture between edges of said plates to receive light from the corresponding channel, and a curved edge joining said plates to focus light from said channel at a detecting location.

17. In an apparatus as defined in claim 16 wherein said edge of each of said guides extends along a segment of a parabola having its focus at said detecting location.

18. In an apparatus for measuring the wavelength of a short pulse of monochromatic laser light, an order filter for receiving and transmitting a light pulse within a predetermined wavelength band, means for resolving said wavelength band into a plurality of wavelength intervals comprising a wedge interference filter for receiving light transmitted by said order filter and transmitting the light to provide a line of light at a position along the length of the filter dependent on the wavelength of the light, and an encoding mask adjacent said filter for resolving the length of the filter into intervals corresponding to said wavelength intervals, said mask receiving said line of light and selectively transmitting or blocking predetermined portions of said line of light to tramsmit a unique combination of said portions for each of said plurality of wavelength intervals within said band, and detecting means including a plurality of detectors, one for each of said portions of said line of light and activable by light to detect the transmission of the corresponding portion of the line of light by the encoding means and means for indicating the activated ones of said detectors.

19. In an apparatus as defined in claim 18 wherein said apparatus includes high sensitivity light detecting means for rendering said detecting means effective to indicate the activated ones of said detectors only in response to detection of a predetermined light signal.

20. In an apparatus for determining the wavelength of light, first means for receiving and transmitting the light whose wavelength is to be measured, and a plurality of detectors, said first means comprising means for selectively transmitting or blocking light to each of said detectors as a function of the wavelength of the light, to transmit unique combinations of inputs to said detectors for different wavelengths.

21. In an apparatus as defined in claim 20 wherein said means for selectively transmitting or blocking light comprises means for forming a line of light in response to an input at a position along a path which is a function of the wavelength;

and coding means for receiving said line of light and selectively transmitting or blocking said line of light to said detectors.

22. An apparatus as defined in claim 21 wherein said coding means comprises a binary mask having a plurality of binary code channels extending perpendicular to said line of light.