Spectrometer apparatus

• US 5,166,755 A
• Filed: 05/23/1990
• Issued: 11/24/1992
• Est. Priority Date: 05/23/1990
• Status: Expired due to Term

• Current Assignee: OPTO-Knowledge Systems, Inc.
• Original Assignee: Nahum Gat
• Inventors: Gat, Nahum
• Primary Examiner(s): Evans, F. L.
• Assistant Examiner(s): HANTIS, KAREN
• Application Number:
  US07/528,070
• Time in Patent Office: 916 Days
• Field of Search: 356/416-419, 356/420, 356/326, 250/226
• US Class Current: 356/419
• CPC Class Codes: G01J 1/429 applied to measurement of ultraviolet light using counting tubes G01T
• CPC Class Codes: G01J 2001/4493 with image intensifyer tube [IIT]
• CPC Class Codes: G01J 2003/1234 Continuously variable IF [CVIF]; Wedge type
• CPC Class Codes: G01J 2003/2806 Array and filter array
• CPC Class Codes: G01J 2003/2826 Multispectral imaging, e.g. filter imaging
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G01J 3/027 Control of working procedures of a spectrometer; Failure detection; Bandwidth calculation
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01J 3/2803 using photoelectric array detector

Abstract

A spectrometer apparatus uses a spectrum resolving sensor containing an opto-electronic monolithic array of photosensitive elements, each preferably sub-millimeter in size and pitch, and a continuous variable optical filter, that is permanently aligned with the array. Polychromatic light passing through the variable filter is spectrally resolved in accordance with the local filter transmission function, and is incident upon the photosensitive elements in the array. The electrical output of each element in the array is thence a function of the local transmission function of the variable filter and the output of all the elements provides the spectral contents of the polychromatic light. High spectral resolving power is obtained by subtraction of the output signal of adjacent elements in the array.

Claims

1. In a spectrometer apparatus for receiving and analyzing polychromatic light, the combination comprising:

a continuous variable wavelength optical filter means of a predetermined length, said optical filter means for receiving said polychromatic light simultaneously over and along a first side thereof and for transmitting out and along a second side thereof, opposed to said first side, spectral filtered portions of received polychromatic light;

said spectral portions being variable in spectral range in dependence upon position along the length of said optical filter means, whereby the particular spectral range of light transmitted through said second side of said optical filter means at selected positions along the length thereof is dependent upon relative position along said length of said optical filter means;

a monolithic substrate, including a plurality of photosensitive elements formed thereon;

said photosensitive elements being arranged in at least one row to form an array;

each of said photosensitive elements for providing an output representative of intensity of light incident thereon;

said optical filter means being located in overlying relationship with said array with said second side of said optical filter means facing said array, whereby different spectral ranges of light are incident upon different photosensitive elements of said array with said array producing an output representative of the light level of different ranges of light spectrum passed by said optical filter means at different positions along the length of said optical filter means;

electronic means for reading the output of said array to provide an output representative of the spectral characteristics of said received polychromatic light; and

support means for supporting at least said optical filter means and said substrate means in a unitary assembly; and

wherein said monolithic substrate is of a slightly curved geometry and said optical filter means is of a slightly curved geometry with the curve of the one being substantially the same as the curve of the other to define a curved focal plane.

2. In a spectrometer apparatus for receiving and analyzing polychromatic light, the combination comprising:

a continuous variable wavelength optical filter means of a predetermined length, said optical filter means for receiving said polychromatic light simultaneously over and along a first side thereof and for transmitting out and along a second side thereof, opposed to said first side, spectral filtered portions of received polychromatic light;

said spectral portions being variable in spectral range in dependence upon position along the length of said optical filter means, whereby the particular spectral range of light transmitted through said second side of said optical filter means at selected positions along the length thereof is dependent upon relative position along said length of said optical filter means;

a monolithic substrate, including a plurality of photosensitive elements formed thereon;

said photosensitive elements being arranged in at least one row to form an array;

each of said photosensitive elements for providing an output representative of intensity of light incident thereon;

said optical filter means being located in overlying relationship with said array with said second side of said optical filter means facing said array, whereby different spectral ranges of light are incident upon different photosensitive elements of said array with said array producing an output representative of the light level of different ranges of light spectrum passed by said optical filter means at different positions along the length of said optical filter means;

electronic means for reading the output of said array to provide an output representative of the spectral characteristics of said received polychromatic light;

support means for supporting at least said optical filter means and said substrate means in a unitary assembly; and

image intensifier means;

said image intensifier means being located between said optical filter means and said array.

3. In a spectrometer apparatus for receiving and analyzing polychromatic light, the combination comprising:

a continuous variable wavelength optical filter means of a predetermined length, said optical filter means for receiving said polychromatic light simultaneously over and along a first side thereof and for transmitting out and along a second side thereof, opposed to said first side, spectral filtered portions of received polychromatic light;

said spectral portions being variable in spectral range in dependence upon position along the length of said optical filter means, whereby the particular spectral range of light transmitted through said second side of said optical filter means at selected positions along the length thereof is dependent upon relative position along said length of said optical filter means;

a monolithic substrate, including a plurality of photosensitive elements formed thereon;

said photosensitive elements being arranged in at least one row to form an array;

each of said photosensitive elements for providing an output representative of intensity of light incident thereon;

said optical filter means being located in overlying relationship with said array with said second side of said optical filter means facing said array, whereby different spectral ranges of light are incident upon different photosensitive elements of said array with said array producing an output representative of the light level of different ranges of light spectrum passed by said optical filter means at different positions along the length of said optical filter means;

electronic means for reading the output of said array to provide an output representative of the spectral characteristics of said received polychromatic light; and

support means for supporting at least said optical filter means and said substrate means in a unitary assembly;

lens means for receiving said polychromatic light originating on a front side thereof and focusing the light into at least a line on a rear side thereof on said optical filter means;

shutter means for opening and closing a light transmissive path;

said lens means being optically coupled in series with said shutter means; and

wherein said lens means comprises an anamorphic lens means.

4. The invention as defined in claim 3, further comprising:

a portable case, said case having an interior and a front opening for permitting polychromatic light external to said case to enter said interior;

said support means being housed within said interior with said first side of said optical filter means being spaced from and facing said opening to permit external polychromatic light to enter said case and cover the length of said optical filter means;

said shutter means being supported in said front opening of said case, whereby polychromatic light is focused through said lens and by operation of said shutter means is admitted into said interior of said case; and

said electronic means being housed within said interior.

5. The invention as defined in claim 3 wherein said electronic means is formed within and disposed upon said monolithic substrate.

6. The invention as defined in claim 3 wherein said plurality of photosensitive elements in said array further comprise parallel output type photodetectors.

7. The invention as defined in claim 3 wherein said electronic means includes multiplexer means and circuit board means for supporting said multiplexer means and said monolithic substrate in a hybrid assembly.

8. The invention as defined in claim 3 wherein said photosensitive elements of said array comprise charge storage type semiconductor devices, said devices are selected from the group consisting of:

(a) charge coupled device;

(b) charge injection device;

(c) a charge coupled photodiode array;

(d) a self scanned photodiode array; and

(e) a multiplexed photodiode array.

9. The invention as defined in claim 3 wherein said array comprises a plurality of rows to define a two-dimensional array.

10. The invention as defined in claim 3 wherein said optical filter means and said substrate of photosensitive elements are integrally formed in a one piece unitary assembly.

11. The invention as defined in claim 3 wherein said anamorphic lens means comprises a cylindrical lens.

12. The invention as defined in claim 3 wherein said optical filter means comprises and edge type filter.

13. The invention as defined in claim 12 wherein said edge type filter comprises a long-wave pass filter.

14. The invention as defined in claim 3 wherein said optical filter means comprises a band-pass filter.

15. In a spectrometer apparatus for receiving and analyzing polychromatic light, the combination comprising:

a continuous variable wavelength optical filter means of a predetermined length, said optical filter means for receiving said polychromatic light simultaneously over and along a first side thereof and for transmitting out and along a second side thereof, opposed to said first side, spectral filtered portions of received polychromatic light;

said spectral portions being variable in spectral range in dependence upon position along the length of said optical filter means, whereby the particular spectral range of light transmitted through said second side of said optical filter means at selected positions along the length thereof is dependent upon relative position along said length of said optical filter means;

a monolithic substrate, including a plurality of photosensitive elements formed thereon;

said photosensitive elements being arranged in at least one row to form an array;

each of said photosensitive elements for providing an output representative of intensity of light incident thereon;

said optical filter means being located in overlying relationship with said array with said second side of said optical filter means facing said array, whereby different spectral ranges of light are incident upon different photosensitive elements of said array with said array producing an output representative of the light level of different ranges of light spectrum passed by said optical filter means at different positions along the length of said optical filter means;

electronic means for reading the output of said array to provide an output representative of the spectral characteristics of said received polychromatic light; and

support means for supporting at least said optical filter means and said substrate means in a unitary assembly;

said electronic means including;

means for subtracting the output of one photosensitive element in said row from the corresponding output of an adjacent element in said row that precedes said one photosensitive element in position in said row to produce a different signal; and

means for outputting said difference signal as representative of the spectral characteristic detected by said adjacent element.

16. The invention as defined in claim 15 further comprising:

means for selecting said one of the plurality of adjacent elements from which to subtract the output of said one photosensitive lement prior to subtraction by said means for subtracting.

17. The invention as defined in claim 15 further comprising:

display means responsive to said electronic means for visually displaying the output of said electronic means to thereby visually depict the spectral characteristics of the incident light as measured by said array and processed by said electronic means.

18. In a spectrometer apparatus for receiving and analyzing polychromatic light, the combination comprising:

a continuous variable wavelength optical filter means of a predetermined length, said optical filter means for receiving said polychromatic light simultaneously over and along a first side thereof and for transmitting out and along a second side thereof, opposed to said first side, spectral filtered portions of received polychromatic light;

said spectral portions being variable in spectral range in dependence upon position along the length of said optical filter means, whereby the particular spectral range of light transmitted through said second side of said optical filter means at selected positions along the length thereof is dependent upon relative position along said length of said optical filter means;

a monolithic substrate, including a plurality of photosensitive elements formed thereon;

said photosensitive elements being arranged in at least one row to form an array;

each of said photosensitive elements for providing an output representative of intensity of light incident thereon;

said optical filter means being located in overlying relationship with said array with said second side of said optical filter means facing said array, whereby different spectral ranges of light are incident upon different photosensitive elements of said array with said array producing an output representative of the light level of different ranges of light spectrum passed by said optical filter means at different positions along the length of said optical filter means;

electronic means for reading the output of said array to provide an output representative of the spectral characteristics of said received polychromatic light; and

support means for supporting at least said optical filter means and said substrate means in a unitary assembly and wherein said electronic means comprises;

electronic processor means containing a program;

said processor means including;

first means for obtaining output from said array to provide spectral intensity information in analog form for the individual photosensitive elements in said array;

analog to digital converter means for converting output of said first means into digital form to provide spectral intensity information in digital form;

interface means for receiving output from said first means and supplying said output under control of said processor means to said analog to digital converter means;

an image buffer for storing said digital form spectral intensity information received from said analog to digital converter means;

digital signal processor means;

calibration memory means containing calibration data on each photosensitive element in said array for supplying said calibration data to said digital signal processor means under control of said electronic processor means;

said digital signal processor means being responsive to said buffer means and said calibration data for providing corrected digital form spectral information at an output; and

display means for receiving said corrected digital form spectral information from said signal processor means and converting said corrected digital form spectral information into a visual display;

said electronic means further comprising;

algorithm means for subtracting the output of any one photosensitive element in said array from the output of any selected adjacent preceding photosensitive element in said array to provide a difference output, said difference output being representative of the spectra detected by said selected adjacent preceeding photosensitive element in said array;

wherein said difference outputs for each photosensitive element may be supplied to said buffer means.

19. A sensor for a spectrometer apparatus comprising in combination:

a monolithic array of photosensitive elements;

continuous variable wavelength optical filter means;

said optical filter means being located in overlying relationship with said array; and

anamorphic lens means located in overlying relationship with said optical filter means for receiving polychromatic light and focusing said polychromatic light into at least a line upon said optical filter means.

20. A sensor for a spectrometer apparatus comprising in combination:

a monolithic array of photosensitive elements;

continuous variable wavelength optical filter means;

said optical filter means being located in overlying relationship with said array; and

with said optical filter means comprising an edge type filter; and

further comprising;

electronic means for polling said array to determine the output of each photosensitive element of said array, said electronic means including means for subtracting the output of any one photosensitive element in a row of said array from any immediately preceding photosensitive element within said row of said array to produce a difference output representative of the spectral range between said adjacent photosensitive elements to thereby provide enhanced spectral resolution.

21. The invention as defined in claim 20, wherein said edge type filter comprises a long-wave pass filter.

22. The invention as defined in claim 20 wherein said edge type filter comprises a short-wave pass type filter.

23. A sensor for a spectrometer apparatus comprising in combination:

a monolithic array of photosensitive elements and continuous variable wavelength optical filter means;

said optical filter means being located in overlying relationship with said array; and

wherein said optical filter means comprises a band-pass type filter and, further comprising;

electronic means for polling said array to determine the output of each photosensitive element of said array, said electronic means including means for subtracting the output of any one photosensitive element in a row of said array from any immediately preceding photosensitive element within said row of said array to produce a different output representative of the spectral range between said adjacent photosensitive devices to thereby provide enhanced spectral resolution.