Imaging spectroscopic method and apparatus

Claim 2

An imaging spectroscope comprising: a light attenuating narrow band pass optical filter adapted to pass wavelengths of light energy within a restricted spectral band and to block substantially all wavelengths of light energy outside of said band; means to form an image of an object or scene under observation solely with light energy passing said filter; and means to intensify said image to a level adequate for spontaneous and direct visual observation, said intensifying means being sensitive at least to light energy throughout the entire wavelength range of visible light.

Claim 3

The apparatus recited in claim 1 wherein said filter is a continuously variable elongated interference wedge filter and including means to support said wedge filter for adjustment along the length thereof relative to said image forming means whereby the restricted spectral band of light energy wavelengths passing said filter may be adjusted through the wavelength range of said wedge filter.

Claim 4

The apparatus recited in claim 2 wherein said wedge filter is in the shape of an annulus, said supporting means including a rotatably adjustable shaft concentric with said annulus and driveably connected to said wedge filter.

Claim 5

The apparatus recited in claim 2 wherein the wavelength range of said wedge filter extends from approximately 3000 A units to 10,000 A units.

Claim 6

The apparatus recited in claim 2 wherein said image forming means includes an aperture diaphragm, said diaphragm being located in close axial proximity to said wedge filter so that the diameter of said diaphragm aperture approximates the size of a portion of said wedge filter operative to pass light energy, thereby to establish the spectral band width of light energy wavelengths passing said wedge filter.

Claim 7

The apparatus recited in claim 1 wherein said filter is one of a group of interchangable filters, each of said interchangable filters having a specific spectral band pass, the passing wavelength range of the group extending from approximately 3000 A units to 10,000 A units.

Claim 8

The apparatus recited in claim 6 including means to support each of said filters for tilting adjustment with respect to the axis of said image forming means whereby the center wavelength of the spectral band passing each such filter may be adjusted through a limited range of band pass wavelengths.

Claim 9

The apparatus recited in claim 7 wherein the limited range of each one of said interchangable filters overlaps with the limited range of another of each such interchangable filters whereby any desired band pass center wavelength in the range of the group of said interchangable filters may be selected by selection of a particular filter and adjustment thereof to a particular angle of tilt with respect to the axis of said image forming means.

Claim 10

The apparatus recited in claim 1 wherein said filter is a interference filter having a nominal center transmittance wavelength when oriented at 90* with respect to the axis of incident light transmitted from the object or scene and comprising further, means to support said filter at a precise angular orIentation with respect to the axis of said image forming means whereby the restricted spectral band of light energy wavelengths passing said filter may be adjusted to a precise center wavelength.

Claim 11

The apparatus recited in claim 9 wherein said filter support means includes means to fix the angular relation of said filter in relation to the axis of said image forming means.

Claim 12

The apparatus recited in claim 1 wherein said image forming means comprises an objective lens having an external housing barrel concentric with the axis of said lens, support means for retaining said filter on the axis of said objective lens and light shield means operative between said filter and said lens barrel to exclude all but light energy passing said filter from passing said lens.

Claim 13

The apparatus recited in claim 11 wherein said filter is a interference filter having a nominal center transmittance wavelength when disposed at 90* to the axis of said objective lens, and wherein said support means comprises means to retain said filter tilted at an angle to said axis such that the filter is tuned to a predetermined center transmittance wavelength other than said nominal center wavelength.

Claim 14

The apparatus recited in claim 12 wherein said filter retainer means includes releasable holding means to secure said filter, whereby said filter may be interchanged with other such filters having different nominal transmittance wavelengths.

Claim 15

The apparatus recited in claim 12 wherein said support means carries an indicating adjustment means connected to said filter retaining means thereby to enable variable adjustment of the angle at which said filter is tilted with respect to the lens axis.

Claim 16

The apparatus recited in claim 14 wherein said light shield means comprises a flexible bellows extending between said filter retaining means and said lens barrel irrespective of the tilt angle to which said filter is adjusted.

Claim 17

The apparatus recited in claim 12 wherein said filter retaining means includes means for adjustably fixing said filter at an angle with respect to said lens axis wherein the center transmittant wavelength of said filter is precisely tuned.

Claim 18

An imaging spectroscope comprising: light attenuating narrow band pass optical filter means to pass only wavelengths of light energy within a restricted spectral band and to block substantially all other wavelengths of light energy, said restricted spectral band being one of many within a spectral range including at least all visible light energy wavelengths; means to form an attenuated two-dimensional image of an object or scene under observation from light energy transmitted therefrom and passing said filter means whereby the light energy forming said image is limited solely to wavelengths within said spectral band and the intensity of said image attenuated to a level substantially below the intensity level of light energy transmitted from the object or scene; and means to intensify said attenuated image to a level sufficient for spontaneous and direct visual observation, irrespective of where in said spectral range, the particular restricted spectral band of light energy passing said filter to form said image may lie.

Claim 19

An imaging spectroscope comprising: light attenuating narrow band pass optical filter means to pass only wavelengths of light energy within a restricted spectral band and to block substantially all other wavelengths of light energy, said restricted spectral band being one of many within a spectral range including at least all visible light energy wavelengths; means to form an attenuated two-dimensional image of an object or scene under observation from light energy transmitted therefrom and passing said filter means whereby the light energy forming said image is limited solely to wavelengths within said spectral band and the intensity of said image attenuated to a level substantially below the intensity level of light energy transmitted from the object or scene; and means to intensify said attenuated image to a level sufficient for spontaneous and direct visual observation, irrespective of where in said spectral range, the particular restricted spectral band of light energy passing said filter to form said image may lie.

Claim 22

The method recited in claim 18 wherein said filtering step is effected by passing Light energy transmitted from the object or scene through a finite portion of a continuously variable interference wedge filter, thereby to establish said restricted spectral band and comprising further the step of filtering different spectral bands of light energy wavelengths transmitted from the object or scene to enable such observation of correspondingly different spectrally contrast enchanced images of the same object or scene.

Claim 23

The method recited in claim 19 wherein said image is formed by an objective lens having an adjustable diaphragm stop aperture and including further the step of varying the width of said restricted spectral band by variation in the size of said aperture.

Claim 24

The method recited in claim 18 wherein said filtering step is effected with a narrow band pass interference filter and comprising further the step of tilting said interference filter to adjust the center wavelength of said restricted spectral band.

Claim 25

The method recited in claim 21 comprising further the step of interchanging one or more of a group of interference filters each being capable of passing different restricted spectral bands of light energy wavelengths within said spectral range.

Claim 26

The method recited in claim 22 wherein the spectral band passing each of said group of filters extends to or within the spectral band of a successive filter within said group thereby to enable observation of said image in increments of said full spectral range.

Claim 27

The method recited in claim 23 comprising further the step of adjustably tilting each of said group of interference filters with respect to a position normal to incident light rays transmitted from said object or scene thereby to enable observation of said image formed by light energy wavelengths within differing restricted spectral bands for each of said group of filters.

Claim 28

The method recited in claim 18 comprising the step of tuning a narrow band pass interference filter to a precise center wavelength of said restricted spectral band.

Claim 29

The method recited in claim 25 wherein said tuning step is effected by mounting said interference filter for adjustable tilting movement in a support having an axis coincident with the axis of light energy to be transmitted from the object or scene under observation; passing a monochromatic beam of light through said filter to means sensitive to the intensity of light passing said filter; adjusting the tilt angle of said angle filter until the intensity of said monochromatic light passing said filter reaches a maximum value; and fixing the tilt angle of said filter in said mount to the position at which the intensity of said monochromatic light passing said filter is maximum.