Abstract: An apparatus incorporated within a spectroscopic imaging system, typically a microscope, but also applicable to other image gathering platforms, namely fiberscopes, macrolens imaging systems and telescopes employing a polarizing beam splitting element is disclosed. The apparatus allows simultaneous spectroscopic (i.e. chemical) imaging and rapid acquisition spectroscopy to be performed without the need for moving mechanical parts or time sequenced sampling and without introducing significant optical signal loss or degradation to the spectroscopic imaging capability. In addition, the apparatus affords a more compact design, an improved angular field of view and an improved overall ruggedness of optical design at a lower manufacturing and maintenance cost compared to previous devices.

Abstract: A metrology device with a rotatable polarizer is calibrated to align the transmission axis of the polarizer with the axis of orientation of a sample, such as a diffraction grating. The axis of orientation of the diffraction grating can be either the TE or TM axis. The system offset angle between the transmission axis of the polarizer in its home position and an axis of motion of the stage, such as a polar coordinate stage, is determined. Whenever a new substrate is loaded onto the stage, the sample offset angle between the axis of motion of the stage and the axis of orientation of a sample is measured. The polarizer offset angle, which is the angle between transmission axis of the polarizer and the axis of orientation of the sample, is the sum of the system offset angle and the sample offset angle. Thus, by rotating the polarizer by an amount equivalent to the sum of the system offset angle and the sample offset angle, the polarizer offset angle is reduced to zero.

Abstract: An optical spectrum analyzer comprises a diffraction grating (DG), a polarization decomposing unit (PDM) for decomposing the input light beam into first and second light beams having mutually-perpendicular linear states of polarization, and two output ports (FP2/1, FP2/2) each for receiving from the grating, substantially exclusively, a respective one of the polarized light beams (LT, LR) after diffraction by the diffraction grating (DG).

Abstract: A spectrometer uses collimated, P-polarized light made incident on a surface of an optically transparent material at angle &thgr;INC. The material transmits the light which reaches a boundary surface between the input material and an output optically transparent material. The input material is preferably highly dispersive, making Snell component values at the boundary surface markedly different for different wavelengths. The output material is preferably of low dispersion and high birefringence. Only one wavelength at the boundary surface has a Snell component value tangent to its corresponding index surface in the output section. Within this section, the ray vector for this wavelength is parallel to the boundary surface. Because optical energy propagates in the ray vector direction, only the narrow range of wavelengths having ray vectors substantially parallel to the boundary surface reach an output surface of the device. This narrow range of wavelengths comprises the passband incident on a detector.

Abstract: A polarized sample beam of broadband radiation is focused onto the surface of a sample and the radiation modified by the sample is collected by means of a mirror system in different planes of incidence. The sample beam focused to the sample has a multitude of polarization states. The modified radiation is analyzed with respect to a polarization plane to provide a polarimetric spectrum. Thickness and refractive information may then be derived from the spectrum. Preferably the polarization of the sample beam is altered only by the focusing and the sample, and the analyzing is done with respect to a fixed polarization plane. In the preferred embodiment, the focusing of the sample beam and the collection of the modified radiation are repeated employing two different apertures to detect the presence or absence of a birefringence axis in the sample. In another preferred embodiment, the above-described technique may be combined with ellipsometry for determining the thicknesses and refractive indices of thin films.

Abstract: A combined spectrometer/polarimeter device capable of being placed in-line in a WDM optical transmission system is provided. The combined device contains an optical waveguide, wavelength manipulating optics that include one or more wavelength dispersive elements formed in the waveguide, and polarization manipulating optics. The wavelength dispersive elements tap at least a portion of the propagating light from the waveguide, such that the tapped light is directed to or through at least a portion of the polarization manipulating optics. The presence of the wavelength dispersive element(s) allow monitoring of one or more channels present in the propagating light. Thus, the device is able to act as a spectrometer to determine the presence/intensity of channels in the WDM system. In addition, by inclusion of the polarization-manipulating optics, it is further possible to use the same in-line device to monitor polarization characteristics of each such channel (e.g.

Abstract: Achromatic optics may be employed in spectroscopic measurement systems. The achromatic optics comprises a spherical mirror receiving a beam of radiation in a direction away from its axis and a pair of lenses: a positive lens and a negative meniscus lens. The negative meniscus lens corrects for the spherical aberration caused by off-axis reflection from the spherical mirror. The positive lens compensates for the achromatic aberration introduced by the negative lens so that the optics, as a whole, is achromatic over visible and ultraviolet wavelengths. Preferably, the two lenses combined have zero power or close to zero power. By employing a spherical mirror, it is unnecessary to employ ellipsoidal or paraboloidal mirrors with artifacts of diamond turning which limit the size of the spot of the sample that can be measured in ellipsometry, reflectometry or scatterometry.

Abstract: An optical signal performance monitoring apparatus in a multi-channel optical transmission system and a method for monitoring the optical signal performance are provided. To achieve the above objective, the optical signal performance monitoring apparatus in the multi-channel optical transmission system includes; an optical input unit for controlling the spot size of an inputted multi-channel optical signal and generating the 1st multi-channel beam; an optical collimation and focusing unit for collimating the 1st multi-channel beam and focusing the 2nd multi-channel beam which is divided by wavelength; a diffraction and reflection unit for diffracting and reflecting the 1st collimated multi-channel beam, and generating the 2nd multi-channel beam which is divided by wavelength and is in parallel with the 1st collimated multi-channel beam; an optical detection unit for measuring the intensity of the 2nd multi-channel beam by wavelength, which is focused by wavelength by the optical collimation and focusing unit.

Abstract: The present invention relates to a spectrometer module comprising an input, for receiving an incoming optical signal, a variable differential group delay (DGD) element, for applying a variable birefringence retardation to said incoming optical signal, and a detector unit for detecting the power of a signal exiting said variable DGD element, having a defined state of polarization. It also relates to a monitor module, a monitoring unit and a monitoring system, comprising such a spectrometer module for use in monitoring an optical network.

Abstract: An apparatus for obtaining information on critical dimensions and overlay accuracy of features in a semiconductor structure comprises a light source, a detector and an optical means defining a first optical path and a second optical path. The first optical path and the second optical path are oriented in correspondence with the respective orientations of diffracting patterns provided on the semiconductor structure to obtain the required information without the necessity of rotating the semiconductor structure. This insures a significantly higher throughput.

Abstract: A tunable spectrometer configured to microsample minute samples of dimension on the order of 10 &mgr;m or less. A tunable optical parametric oscillator laser is used to produce a sampling beam and a reference beam for measuring the absorption of the samples.

Abstract: A light analyzer with a first light source configured and disposed for irradiating with a first light an object disposed at an object location. A second light source is configured and disposed for irradiating the object with a second light that is preferably polarized along a first axis. A light receiving element is configured and disposed for receiving the first and second light reflected from the object and comprising a sensing device that is configured for sensing and producing an image corresponding to the reflected light. The light receiving element preferably comprises a polarizing filter configured for polarizing the reflected second light along a second axis at an angle to the first axis for reducing glare and reflection.

Abstract: Apparatus for analysing a sample comprises: a. A radiation source for generating a radiation beam; b. A sample holder for holding the sample in use; c. A polariser for polarising the radiation beam; d. A radiation beam selector for selectively exposing the sample to either the radiation beam or the polarised radiation beam; and, e. A detector for detecting radiation emitted by the sample.

Abstract: Polarization-dependent losses (PDL) are balanced in an optical system through the use of a weak polarizer placed in an optical path so as to compensate for the static PDL of the rest of the system. The weak polarizer comprises an interface or a layer of material having a different refractive index in the operating wavelength band, placed in the optical path at an angle to provide a desired level of PDL compensation. The geometry and indices of the two material are deliberately chosen to compensate for PDL elsewhere in the system. One implementation of the invention involves the use glass and air as the two materials, either in the form of a prism or a glass plate. The invention may alternatively take the form of a weak polarizer adhered to, or sandwiched between, a block of optical material such as glass. Preferably, a material having an index close to that of glass would be used in such a case, such as a polymer.

Abstract: An apparatus for testing critical design parameters in liquid crystal devices compensates for system-imposed influences on measured values, provides real-time correction for variations in spectral content of the source illumination and permits optimization of the values of control parameters.

Abstract: Methods and apparatus for generating multispectral images of tissue. The multispectral images may be used as a diagnostic tool for conditions such as cervical cancer detection and diagnosis. Primary radiation is produced with an illumination source. The primary radiation is filtered to select a first wavelength and a first polarization. Tissue is illuminated with the filtered primary radiation to generate secondary radiation, which is filtered to select a second wavelength and a second polarization. The filtered secondary radiation is collected with a detector, and a plurality of multispectral images of the tissue is generated according to different combinations of first and second wavelengths and first and second polarization with an analysis unit in operable relation with the detector. Apparatus utilizing the invention include endoscopes and colposcopes.

Abstract: In determining an intrinsic spectrum from a measured spectrum using the Maximum Entropy Algorithm, it is hardly or even not at all practical to determine the eigenvalues of an N×N matrix of large dimensions (N of the order of from 104 to 105). According to the invention such a large matrix is subdivided into a large number of much smaller partial matrices that are located on the diagonal or trace of the large matrix. The set of eigenvalues to be determined then consists of all eigenvalues of the partial matrices which can be determined much faster. Because of the Toeplitz-like character of the partial matrices, their eigenvalues can be determined very fast by Fourier transformation of a single row of such a matrix. Using the set of eigenvalues thus obtained, the intrinsic spectrum is determined by means of a minimizing algorithm.

Abstract: Achromatic optics may be employed in spectroscopic measurement systems. The achromatic optics comprises a spherical mirror receiving a beam of radiation in a direction away from its axis and a pair of lenses: a positive lens and a negative meniscus lens. The negative meniscus lens corrects for the spherical aberration caused by off-axis reflection from the spherical mirror. The positive lens compensates for the achromatic aberration introduced by the negative lens so that the optics, as a whole, is achromatic over visible and ultraviolet wavelengths. Preferably, the two lenses combined have zero power or close to zero power. By employing a spherical mirror, it is unnecessary to employ ellipsoidal or paraboloidal mirrors with artifacts of diamond turning which limit the size of the spot of the sample that can be measured in ellipsometry, reflectometry or scatterometry.

Abstract: Fluorescence imaging of tissue is used as a diagnostic tool in which geometric effects and specular reflections are compensated for by normalizing a fluorescence image with a cross-polarized image.

Abstract: Achromatic optics may be employed in spectroscopic measurement systems. The achromatic optics comprises a spherical mirror receiving a beam of radiation in a direction away from its axis and a pair of lenses: a positive lens and a negative meniscus lens. The negative meniscus lens corrects for the spherical aberration caused by off-axis reflection from the spherical mirror. The positive lens compensates for the achromatic aberration introduced by the negative lens so that the optics, as a whole, is achromatic over visible and ultraviolet wavelengths. Preferably, the two lenses combined have zero power or close to zero power. By employing a spherical mirror, it is unnecessary to employ ellipsoidal or paraboloidal mirrors with artifacts of diamond turning which limit the size of the spot of the sample that can be measured in ellipsometry, reflectometry or scatterometry.

Abstract: A velocity such as wind velocity is measured based on a Doppler shift of a backscattered or returned laser signal. The Doppler shift of the backscattered beam is determined from a change in the polarization state or intensity shift of the received or backscattered signal after it has passed through a polarization-dispersive element (PD) and through a polarization analyzer (PA). The electrical signals (I1 and I2) generated from two partial beams provided by the polarization analyzer (PA) represent an the intensity shift. The signals are processed in a computer and the resulting information is displayed, for example.

Abstract: An optical spectrum analyzer comprises a diffraction grating (DG), a polarization decomposing unit (PDM) for decomposing the input light beam into first and second light beams having mutually-perpendicular linear states of polarization, and two output ports (FP2/1, FP2/2) each for receiving from the grating, substantially exclusively, a respective one of the polarized light beams (LT, LR) after diffraction by the diffraction grating (DG).

Abstract: The invention concerns a micropolarimeter comprising an analyzer (1) and a detector (10) located past the analyzer in the direction of radiation and presenting a number of segments ND which is higher than or equal to 3 (11). The invention seeks to provide a micropolarimeter with no moving parts, with a high polarization index, for use for polychromatic light, so small that it can detect the ray of common lasers in one single measurement step without it being necessary to enlarge it, and capable of being converted in a simple manner into a complete Stokesmeter.

Abstract: An optical monochromator has high signal selectivity and low insertion loss, and is well-suited for characterizing a variety of optical signals, including closely-spaced optical channels within DWDM systems. The optical monochromator includes a bulk-optic polarization beam splitter that separates orthogonal polarization states of an applied optical signal into separate optical beams. Low insertion loss is achieved by reconciling the polarization states of the separate optical beams to an optimum polarization state that minimizes insertion loss when the optical beams are applied to a dispersive element. High signal selectivity is achieved using a multipass configuration and by illuminating large areas of the dispersive element, since large beam diameters are accommodated by the bulk-optic polarization beam splitter.

Abstract: This invention provides an inexpensive, noninvasive optical method of quantitatively determining the volume fraction of anisotropic material in a mixture of anisotropic and isotropic material, and more particularly for determining the volume fraction of noncubic crystalline material in a mixed-phase specimen having noncubic crystalline material intermixed with cubic crystalline material. Polarized light is impinged on the specimen and the reflectance or transmission difference between two orthogonal polarization directions is measured. In cubic regions the reflectance or transmission is the same along both polarization directions so the contributions to the difference cancel, leaving a signal only from the noncubic regions. The optical difference can be measured as a function of wavelength and critical points in the band structure, including the band gap, can be profiled. From the band structure the film composition can be determined.

Abstract: The present invention provides a new analysis based on Differential Spectral Topographic Analysis (DISTA). Using data from the spectral methods known in the art, DISTA is based upon the normalization of the spectra to a fixed topographic space, creating a set of spectral forms, and the summation of the absolute differences in topography between one or more reference spectra and the test spectra taken at different magnitudes of the perturbing parameter. This method allows for a sensitive estimate of the fraction of form A and form B of an entity of interest. This method also allows for the calculation of apparent free energy from the conversion of the entity of interest from a first to a second form where appropriate, and in the alternative, calculation of a fraction of structural changes.

Abstract: A retarder system and method of its use in ellipsometers and polarimeters are disclosed. The retarder system is a parallelogram shaped element which, as viewed in side elevation, has top and bottom sides which are parallel to one another. The retarder system also has right and left sides which are parallel to one another, with both the right and left sides being oriented at an angle to the top and bottom sides. The retarder system is made of a material with an index of refraction greater than that of a surrounding ambient.

Abstract: A processing unit reads out, from a memory, wavelength setting data corresponding to wavelength information from a key input section, and outputs a wavelength setting command corresponding to the wavelength setting data to a tunable-wavelength control section and a spectral wavelength control section. The tunable-wavelength control section controls a tunable-wavelength light source section to output a laser beam having a wavelength corresponding to the wavelength setting data. The spectral wavelength control section controls a spectroscope section to perform spectroscopy of the light having the wavelength corresponding to the wavelength setting data and output the resultant light. Output light from the tunable-wavelength light source section whose wavelength has been set is input to an object to be measured. Light passing through the object is input to the spectroscope section. The spectroscope section performs spectroscopy of only the light having the wavelength corresponding to the wavelength setting data.

Abstract: An electronically agile spectro-polarimetric imager is described in which an acousto-optic tunable spectral filter (AOTF) is located in series with an electronically tunable optical phase modulation plate such that incident radiation will pass through the modulation plate and the AOTF in sequence. This system makes it possible to perform both spectral analysis, complex polarization analysis and object discrimination at video-rates of incident radiation from complex target scenes according to the spectral content and polarization state of the radiation reflected or emitted from the objects within the scene, regardless of the polarization state of the incident radiation. Embodiments for analyzing incident radiation of various wavelengths are provided.

Abstract: The invention uses a resonance Raman spectrometer 1 for achieving the identification and quantitation of analytes including biomolecules, organic and inorganic molecules. According to the present invention, a) a sample 2 is deuterated 3 with D20 for facilitating identification and quantitation of analytes 4 of said sample, b) a monochromatic light 6 illuminates sample 2 of analytes 4 for producing Raman sample light 12 and rejecting Rayleigh light 14, c) the Raman sample light 12 is passed through a depolarizer 19 for producing randomized polarization components 20, d) a Raman sample spectrum 22 is generated, calibrated with respect to an absolute differential Raman cross-section standard in response to said randomized polarization components 22, e) the Raman sample spectrum 22 is provided to a spectral analyzer 24 for identification 26 and/or quantitation 28 of the analytes 4.

Abstract: A bio-molecule analyzer including a plurality of test sites on a transparent substrate, each test site having probe molecules attached thereto. An array of addressable light sources are positioned in optical alignment with a corresponding test site. A solution containing sample molecules is positioned in contact with the plurality of test sites. A detector array having a plurality of photodetectors positioned in optical alignment with the array of addressable light sources, one photodetector corresponding to each light source, and a light filter positioned between the detector array and the plurality of test sites for absorbing the light from the light sources and transmitting the light from the test sites to the detector array.

Abstract: Achromatic optics may be employed in spectroscopic measurement systems. The achromatic optics comprises a spherical mirror receiving a beam of radiation in a direction away from its axis and a pair of lenses: a positive lens and a negative meniscus lens. The negative meniscus lens corrects for the spherical aberration caused by off-axis reflection from the spherical mirror. The positive lens compensates for the achromatic aberration introduced by the negative lens so that the optics, as a whole, is achromatic over visible and ultraviolet wavelengths. Preferably, the two lenses combined have zero power or close to zero power. By employing a spherical mirror, it is unnecessary to employ ellipsoidal or paraboloidal mirrors with artifacts of diamond turning which limit the size of the spot of the sample that can be measured in ellipsometry, reflectometry or scatterometry.

Abstract: A method of measuring surface reflectance of a polarizing film product and for producing an antireflective polarizing film. The method includes placing a linear polarizer between a polarizing film product and a light supplying part, and measuring light reflected by the surface of the film.

Abstract: A method is described by which the association between an oligonucleotide labeled by attachment of a fluorophore and another macromolecule such as a protein or nucleic acid may be determined quantitatively in solution accurately and with high sensitivity. In the performance of this method the polarization of fluorescence of an extrinsic fluorescence probe that is covalently coupled to the oligonucleotide is determined. Changes in fluorescence polarization are related directly to the degree of association between the labeled oligonucleotide and another macromolecule and may be used to quantify the association. Because of its high sensitivity and accuracy, this method may be used to make reliable quantitative measurements of very small amounts of complexes formed between labeled oligonucleotides and proteins, nucleic acids or other macromolecules. The method also allows the accurate calculation of important biochemical parameters such as dissociation constants.

Abstract: A spectroscopic system for the analysis of small and very small quantities of substances makes use for the purposes of energy transfer of cone-shaped aperture changers (14, 15) which are arranged in the object zone (8) between the light source (L) and the sample (9) and, during absorption measurements, also between the sample (9) and the inlet slot (3) of a spectrometer (1). If the form used is a double cone, the aperture changers (14, 15) facilitate an oblique coupling in a capillary tube accepting the sample (9) which acts as a step-waveguide for the coupled radiation.

Abstract: A spectrum measuring device for measuring optical spectrum of input light includes first and second double-image elements which separate input light to be measured into two polarized wave components having respective planes of polarization perpendicularly intersecting each other and having different optical axes, a third double-image element which separates the two polarized wave components from the first and second double-image elements into four polarized wave components each two of which having respective planes of polarization perpendicularly intersecting each other and having different optical axes, a dispersing element which is irradiated by the four polarized wave components from the third double-image element in which the dispersing element separates optical components of each wavelength contained in the four polarized wave components at the same angle of separation, and a photodetector for measuring an overall intensity of the four polarized wave components of the same wavelength separated by the dis

Abstract: The dichrograph and accompanying method are usable for parallel measurement of circular dichroism according to the first harmonic of photoelectric current of the detector, optical rotation according to the second harmonic and transparency according to the null harmonic. It contains the switch (3) of ray, from which alternatively exit two parallel rays--measurement ray (4) and reference ray (5), going through one mutual modulator of ellipticity (6), achromatic phase element (9) which is during calibration of circular unit situated in the reference ray (5). Moreover it contains two analyzers--the measurement analyzer (8) in the measurement ray (4) behind the couvette (7) and the reference analyzer (10) in the reference ray (5). The measurement analyzer (8) has the optical axis turned for 45.degree. same as the modulator (6). The reference analyzer (10) is during measurement turned for unit angle, e.g. for 1.degree., to the measurement analyzer (8).

Abstract: An apparatus and method for modified intrinsic state spectral analysis determines a proportion of a plurality of intrinsic structures of an optically active molecule. A spectropolarimeter generates a plurality of intrinsic spectra. Each of the plurality of intrinsic spectra is an intrinsic state vector corresponding to a plurality of intrinsic molecular structures. The spectropolarimeter also generates a spectrum for a sample of the optically active molecule. The sample spectrum is a sample state vector of the optically active molecule. A controller determines a plurality of estimate state vectors based on a plurality of perturbed intrinsic state vectors. Each of the plurality of perturbed intrinsic state vectors corresponds to a perturbed intrinsic structure. An optimum proportion of the plurality of perturbed intrinsic state vectors corresponds to each estimate state vector. The plurality estimate state vectors are matched against the sample state vector to determine a best match estimate state vector.

Abstract: An optical measurement device is disclosed for evaluating the parameters of a sample. The device includes a polychromatic source for generating a probe beam. The probe beam is focused on the sample surface. Individual rays within the reflected probe beam are simultaneously analyzed as a function of the position within the beam to provide information at multiple wavelengths. A filter, dispersion element and a two-dimensional photodetector array may be used so that the beam may be simultaneously analyzed at multiple angles of incidence and at multiple wavelengths. A variable image filter is also disclosed which allows a selection to be made as to the size of the area of the sample to be evaluated.

Abstract: A dual beam tunable spectrometer comprises a radiation source, generating means, a detector, and a shutter arrangement. The radiation source generates an incident radiative beam. The generating means, which includes an acousto-optic tunable filter, receives the incident radiative beam and generates therefrom a reference beam and a sample beam. The detector detects at least part of the reference beam, and detects at least part of the sample beam emitted from a sample following illumination of the sample with the sample beam. The shutter arrangement includes a first shutter selectively permitting passage therethrough of the part of the reference beam and a second shutter selectively permitting passage therethrough of the part of the sample beam. The shutter arrangement opens the first shutter and closes the second shutter to permit the detector to detect only the part of the reference beam.

Abstract: The invention concerns a method of determining the angle of attack (pretilt angle) of liquid crystal molecules in a liquid crystal display (LCD) provided with top and bottom cover plates. The following steps are proposed for a simple and cheap determination: addition of a dichroic dye (17) to the liquid crystal (5) in order to cause the dye molecules (18) to become aligned by the crystal molecules (6), which are present in a twist-free state, determination by measurement of a maximum absorption value, the said measurement being carried out by causing a polarized ray of light (19) (measuring ray) to pass through the liquid crystal display (1) and varying its angle of inclination (.alpha.) with respect to the plane of the cover plates (2,3), and then using the angle of inclination (.alpha.) associated with the maximum absorption for determining the angle of attack (.delta.).

Abstract: In spectrum measuring equipment the light to be measured is separated by a double-image polarizing element into two polarized wave components whose planes of polarization cross each other perpendicular and which have different optical axes. The two polarized wave components are applied to a dispersing element so that their planes of polarization intersect the direction of light separation at .+-.45.degree. thereto, respectively. The sum of optical powers of the two polarized wave components separated by the dispersing element is measured by a photodetector, so that spectrum measurement independent of the polarization of the light to be measured can be achieved.

Abstract: A spectroscope device of the dispersion type receives light to be measured and emits it as dispersed light which corresponds to each of wavelengths to be measured. An optical-path switching device directs the dispersed light emitted from the spectroscope device to pass through first and second paths. A first photoelectric converter receives the light which is directed to pass through the first path by the optical-path switching device. A polarizing/separating device polarizes and separates the light, which is directed to pass through the second path by the optical-path switching device, into two polarized lights. Second and third photoelectric converters respectively receive the two polarized lights divided by the polarizing/separating device.

Abstract: An apparatus and method simultaneously measures a plurality of spectral wavelengths present in electromagnetic radiation. A modulatable birefringent optical element is employed to divide a polarized light beam into two components, thereby producing a phase difference in two resulting light beams such that the two beams can be made to interfere with one another when recombined, the interference pattern providing the wavelength information required for the analysis of the incident light. The interferometer thus created performs in a similar manner to a Michelson interferometer, but with no moving parts, and with a resolution dependent on the degree of phase shift introduced by the modulator.

Abstract: The invention relates to an optical sample illumination device for a spectroscopic ellipsometer of the rotating analyzer type. The image of the exit slit (F') of a monochromator is conjugated with a point (F'.sub.2) of a surface of a sample (E) by means of two spherical mirrors (M.sub.7 and M.sub.8). An astigmatism correction slit (F'.sub.15) is arranged in the proximity of the conjugate (F'.sub.1) of the exit slit(F') of the monochromator with respect to the spherical mirror (M.sub.7) and is arranged perpendicularly to this exit slit and to the optical path so that said correction slit is conjugated with the said point (F'.sub.2) through the spherical mirror (M.sub.8). A luminous spot without astigmatic errors is thus obtained.

Abstract: In an optical measuring apparatus, a laser beam is transferred to a diffraction grating so that the laser beam is spectrally separated into respective wavelength components. The wavelength components are sequentially guided into a polarizing optical element in which the respective wavelength component are separated into S and P polarized components, when the diffraction grating is rotated. The S and P polarized components of the respective wavelengths are detected by photodetectors and electrical signals from the photodetectors are supplied to a signal processing unit. In the signal processing unit, the electrical signals corresponding to the P and S components are corrected with a spectral efficiency characteristic of the grating, a percent loss characteristic of the polarizing element and photoelectro conversion characteristics of the photodetectors and the corrected signals are analyzed to obtain an absolute value of the laser energy for the respective wavelength.

Abstract: Relative retardation resulting from passage of polarized white light through a stressed transparent material is measured automatically, by dividing the emerging polychromatic light into plurality of component beams, each containing one wavelength (or color) only, transforming the light intensity carried by each component beam into an electrical signal, and using these electrical signals to measure the relative retardation, proportional to the stress in the transparent material.Means are provided to compare the spectral distribution of the light intensity measured at several wavelengths to the calculated distribution using an assumed value of retardation. Iterative (repetitious) calculations are performed until the measured distribution and calculated, using assumed retardation, agree. The retardation yielding agreement with the measured distribution is the measured retardation reflecting the stress in the material.

Abstract: The present invention consists in a grazing incidence reflection spectrometer wherein light is caused to incide on a surface of a sample, and an intensity of light reflected from the sample surface is detected, thereby to measure an electronic absorption spectrum of a material adsorbed to the sample surface, characterized in that the incident light is visible light or ultraviolet light, and that the incident light has a predetermined glancing angle to the sample surface.

Abstract: A frequency agile optical radar system including a frequency agile laser rce coupled with an extra-cavity dispersive element in such a manner as to radiate into space specific optical frequencies correlated with specific elevation angles measured from the horizontal. Laser radiation reflected from an object in space is detected by a staring detector system and the wavelength of the reflected optical energy determined therefrom. The elevation angle of the object in space is correlated with the optical frequency determination and coupled together with target range and aximuth angle so that the position and range to an object in space may be determined.

Abstract: A spectrometer for measuring the spectra and concentration of airborne chemicals at long ranges wherein the optical signals may be occluded by dust. A single lasing medium is utilized both for producing a transmitted optical signal and for amplifying a received optical signal, the frequencies of radiation of the transmitted and received optical signals being offset as the radiation propagates to a distant reflector and back to the lasing medium. The frequency offset is obtained by sweeping the transmitted frequency at a rate commensurate with the round trip propagation time whereby the offset is sufficient to place the received frequency at a peak at the amplifying spectrum of the lasing medium. A laser containing the laser medium further incorporates an interferometric structure within the optical path for sequentially shifting the frequency of oscillation to produce a comb spectrum for sampling the spectra of the chemicals to provide identifying signatures thereof.