Analyzer for coherent radiation

Claim 2

Apparatus for detecting the existence of a coherent source of radiation in the presence of incoherent ambient radiation comprising: aperture means for separating incident radiation into two components to form an etalon path and a reference path; an etalon and a first detector disposed in the etalon path; a path compensating device and a second detector disposed in the reference path to destroy its coherent modulation characteristics; and means for balancing the etalon and reference paths for incoherent radiation and for producing an output indicative of the presence of a coherent source.

Claim 3

Apparatus for detecting the existence of a coherent source of radiation in the presence of incoherent ambient radiation according to claim 1 wherein said aperture means comprises a beam-splitter.

Claim 4

Apparatus for detecting the existence of a coherent source of radiation in the presence of incoherent ambient radiation according to claim 1 wherein said path compensating device is a wedged etalon.

Claim 5

Apparatus for detecting the existence of a coherent source of radiation in the presence of incoherent ambient radiation according to claim 1 wherein said means for balancing the etalon and reference paths for incoherent radiation and for producing an output indicative of the presence of a coherent source comprises a difference amplifier which receives signals from said detectors, an absolute value circuit for receiving the output from said difference amplifier, and a comparator which receives signals corresponding to the output of the second detector and the output of the absolute value circuit.

Claim 6

Apparatus for detecting the existence of a coherent source of radiation in the presence of incoherent ambient radiation according to claim 1 wherein said means for balancing the etalon and reference paths for incoherent radiation and for producing an output indicative of the presence of a coherent source comprises a first comparator which receives signals corresponding to the output of said first detector and signals corresponding to the output of the second detector modified by a constant, a second comparator which receives signals corresponding to the output of said second detector and signals corresponding to the output of the first detector modified by a second constant, and an OR gate for receiving the output of the two comparators.

Claim 9

The method of claim 6 wherein the step of sensing comprises sensing the light at a minimum of three locations along the optical device.

Claim 10

The method of claim 6 wherein the step of comparing includes determining the polarity of the difference between a first sensed magnitude and a value proportional to a second sensed magnitude.

Claim 11

The method of claim 8 wherein determination of a predetermined polarity indicates that the light exceeds at least a selected threshold coherence length.

Claim 12

A light beam coherence length discriminator for discriminating between light beams having coherence lengths above and below a preselected threshold length comprising: means for generating an optical fringe pattern in response to a beam of light incident thereon; sensing means for simultaneously sensing the intensity of the light at a plurality of locations along the generated fringe pattern and producing a plurality of simultaneous output signals indicative of the intensity of the sensed light at the respective locations; and means for evaluating simultaneously the relative values of the output signals of the sensing means to provide an evaluation of the coherence length of the incident light.

Claim 13

A light beam coherence length discriminator for discriminating between light beams having coherence lengths above and below a preselected threshold length comprising: means for generating an optical fringe pattern in response to a beam of light incident thereon; sensing means for simultaneously sensing the intensity of the light at a plurality of locations along the generated fringe pattern and producing a plurality of simultaneous output signals indicative of the intensity of the sensed light at the respective locations; and means for evaluating simultaneously the relative values of the output signals of the sensing means to provide an evaluation of the coherence length of the incident light.

Claim 14

The discriminator of claim 10 wherein said evaluating means includes means to determine the difference between the value of one output signal and a value proportional to the value of another output signal.

Claim 15

The discriminator of claim 11 wherein the evaluating means includes a detector for detecting the polarity of the difference determined by the determining means.

Claim 16

The discriminator of claim 10 wherein the means for generating includes a wedge-shaped optical device.

Claim 17

The discriminator of claim 10 wherein the sensing means comprises an array of light detectors which intercept the generated fringe pattern.

Claim 18

The discriminator of claim 14 wherein the means for generating includes a wedge-shaped optical device.

Claim 19

Apparatus for evaluating the coherence length of a light beam comprising: a wedge-shaped optical member disposed in the path of the light beam to produce a fringe pattern on the side of the optical member opposite that which intercepts the light beam, the fringe pattern being characteristic of the frequency and spectral bandwidth properties of the incident light; a plurality of light detectors disposed at locations of expected maximum and minimum intensities of the fringe pattern for light of a predetermined coherence length, each detector producing an output signal related to the intensity of light at its location; means for evaluating the detector output signals relative to each other as an evaluation of the coherence length of the light beam.

Claim 20

Apparatus for evaluating the coherence length of a light beam comprising: a wedge-shaped optical member disposed in the path of the light beam to produce a fringe pattern on the side of the optical member opposite that which intercepts the light beam, the fringe pattern being characteristic of the frequency and spectral bandwidth properties of the incident light; a plurality of light detectors disposed at locations of expected maximum and minimum intensities of the fringe pattern for light of a predetermined coherence length, each detector producing an output signal related to the intensity of light at its location; means for evaluating the detector output signals relative to each other as an evaluation of the coherence length of the light beam.

Claim 21

The apparatus of claim 16 wherein said evaluating means includes means to determine the difference between the value of one output signal and a value proportional to the value of another output signal.

Claim 22

The apparatus of claim 17 wherein the evaluating means includes a detector for detecting the polarity of the difference determined by the determining means.

Claim 23

Apparatus for discriminating between pulsed beams of light having coherence lengths above and below a preselected coherence length threshold, such light having wavelengths falling within a desired range, comprising: optical means for producing an interference fringe pattern from a pulsed beam of light incident thereon; light detection means disposed adjacent said optical means and disposed to receive the fringe pattern for producing a set of output signals proportional to the maximum and minimum intensities of the fringe pattern; and signal processing means connected to said light detection means for comparing such output signals with one another to determine whether the coherence length of the light is above or below the preselected coherence length threshold.

Claim 24

Apparatus for discriminating between pulsed beams of light having coherence lengths above and below a preselected coherence length threshold, such light having wavelengths falling within a desired range, comprising: optical means for producing an interference fringe pattern from a pulsed beam of light incident thereon; light detection means disposed adjacent said optical means and disposed to receive the fringe pattern for producing a set of output signals proportional to the maximum and minimum intensities of the fringe pattern; and signal processing means connected to said light detection means for comparing such output signals with one another to determine whether the coherence length of the light is above or below the preselected coherence length threshold.

Claim 25

The apparatus as defined in claim 19 in which said optical means is a wedge-shaped block of light transmissive material having its surfaces partially reflective.