EP1523663A1 - Dispositif et procede de spectroscopie optique, capteurs optiques et utilisation dudit dispositif - Google Patents

Dispositif et procede de spectroscopie optique, capteurs optiques et utilisation dudit dispositif

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Publication number
EP1523663A1
EP1523663A1 EP02807594A EP02807594A EP1523663A1 EP 1523663 A1 EP1523663 A1 EP 1523663A1 EP 02807594 A EP02807594 A EP 02807594A EP 02807594 A EP02807594 A EP 02807594A EP 1523663 A1 EP1523663 A1 EP 1523663A1
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EP
European Patent Office
Prior art keywords
interference pattern
spatial
detector
optical
interference
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02807594A
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German (de)
English (en)
Inventor
Thilo Weitzel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Campus Technologies AG
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Campus Technologies AG
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Filing date
Publication date
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Publication of EP1523663A1 publication Critical patent/EP1523663A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/45—Interferometric spectrometry
    • G01J3/453—Interferometric spectrometry by correlation of the amplitudes

Definitions

  • the invention relates to devices and methods for optical spectroscopy and optical sensors.
  • Optical spectrometers can be divided into dispersive or diffractive spectrometers and Fourier transform spectrometers.
  • Dispersive (from prism) or diffractive (grating) spectrometers break down the incident light beam into its spectral components due to the wavelength dependence of a diffraction or reflection angle.
  • the different spectral components are thereby spatially separated and the spectral component to be determined can be selected (monochromator).
  • a spectrum is then recorded with the help of moving parts, in that the various spectral components are selected and measured in succession.
  • the most common are monochromators with a Czerny-Turner beam path, ie with a rotatable plane grating (diffraction grating in reflection) between an entrance and an exit slit and mutually independent collimator or collector mirrors. Collimator and collector create an image of the entry gap in the plane of the exit gap.
  • the diffraction grating is located in the Fourier transform plane of this imaging system.
  • CCD spatially resolving detectors
  • Fourier transform spectrometers are based on an interferometer, in which the difference in the optical path lengths of the partial beams brought into interference can be set with high precision.
  • the spectrum can be determined from a measurement of the interference signal over a suitable range of path length differences by Fourier transformation.
  • Devices are usually constructed in the manner of a Michelson or Twyman Green interferometer.
  • the mechanical components for adjusting the optical path lengths by means of movable mirrors or tiltable mirror pairs as well as the necessary collimator for generating flat wavefronts are particularly demanding.
  • spectrometers uses static interference patterns generated by light beams which are brought to interference at a certain angle, e.g. Fizeau interferometer.
  • the spectrum can be calculated by counting the interference fringes or by determining the spatial frequencies of the interference pattern with the aid of a numerical Fourier transformation.
  • a disadvantage of these interferometric spectrometers is the fact that the relative spectral resolution is determined directly by the number of line pairs measured in the interference pattern (Fizeau stripes) is determined. Become N line pairs for counting a certain wavelength ⁇ , the spectral resolution is on the order of ⁇ / N.
  • spatial heterodyne spectrometer uses dispersive or diffractive optical elements (diffraction gratings) to change the angle between two collimated partial beams of a static interferometer depending on the wavelength and thus to increase the spectral resolution ,
  • Such arrangements are further based on the translational invariance of the optical Fourier transform.
  • the incident light is first collimated by a collimator.
  • the collimated beam (flat wavefronts) is split (amplitude division) and guided over spectrally dispersive or diffractive elements, e.g. a diffraction grating.
  • the spectrally dispersive optical element lies in the Fourier plane of the collimator.
  • the again superimposed partial beams are then imaged by a collector and a further Fourier transform lens in such a way that a spatially resolving detector comes to rest in a Fourier transform plane of the entrance aperture.
  • Such arrangements like Fourier transform spectrometers or conventional monochromators, are therefore dependent on high-quality imaging optical systems. In particular, relatively large focal lengths of the optical systems are required.
  • dispersive or diffractive spectrometers The possible performance of dispersive or diffractive spectrometers is dependent on certain parameters, in particular the dimensions of inlet or Exit slit, the focal length and aperture of the imaging elements and the Properties of the dispersive or diffractive element itself. Modern devices almost reach these physically set limits.
  • the possible performance of Fourier transform spectrometers is correspondingly determined by certain parameters and here in particular by the distance and the step size for the variation of the optical path lengths.
  • the performance of Fourier transform spectrometers far exceeds the possibilities of dispersive or diffractive spectrometers.
  • Fourier transform spectrometers can also almost reach the physical limits of their performance, but the technical effort may be very high. Since Fourier transform spectrometers are based on an interferometer, all optical components and especially the moving parts must be manufactured and positioned with a precision of fractions of the wavelengths to be measured.
  • Spatially heterodyne spectrometers are technically less complex, but also require high quality imaging as well as dispersive or diffractive optical components.
  • the spectrometric arrangement In order to achieve a certain spectral resolution, the spectrometric arrangement must generate defined differences in the optical path lengths of at least length I.
  • the collimator is an imaging optical element of a certain focal length f, for example a concave mirror or a lens.
  • the entry opening of the spectrometer is at the focal point of the collimator.
  • the spectrometers now explicitly use the special properties of the optical Fourier transformation, in particular the translational invariance of the Fourier transformation, i.e. the transformation of a translation in the focal plane to a change in the direction of propagation in the Fourier plane of the collimator.
  • Monochromators (4f system): entrance slit - f - collimator - f - diffraction grating - f - collector - f - exit slit) influence the direction of light propagation in the Fourier plane of the imaging system through a diffraction grating and thus generate the desired spectral dispersion without the image to be significantly disturbed from the entrance slit to the exit slit or detector (I is defined by the geometry of the grating in the beam path, f »I).
  • the collimator carries out an optical Fourier transformation, the collector takes over the optical inverse transformation and thus brings about the optical imaging of the entrance slit in the plane of the exit slit or of the detector.
  • the numerical Fourier transform replaces the optical inverse transform used in the monochromator.
  • spatial heterodyne spectrometer Fourier transform spectrometers with dispersive elements that evaluate a spatial interference pattern (spatial heterodyne spectrometer) require the collimator explicitly in the context of an optical Fourier transformation, on the one hand to avoid smearing the interference pattern despite a finally large entrance opening (translation invariance), on the other hand to the defined and clear attribution to establish the relationship between the optical spectrum and proportions of spatial frequencies in the resulting pattern, which forms the basis of the numerical back transformation.
  • the object of the present invention is to provide a device and a method for realizing spectrometers with high spectral resolution and at the same time substantially lower demands on the quality of the optical components.
  • the object is achieved by an interferometric device according to claim 1 and by the use and method claims.
  • the coupling of the light via defined spatial modes or a mono-mode coupling is essential for the implementation of an inexpensive and spectrally high-resolution spectrometer or sensor according to the invention.
  • the aperture broadening disappears, in particular the interference pattern remains recognizable by a collimator even without optical Fourier transformation and can be evaluated with the aid of the methods shown.
  • Such an optical spectrometer in combination with dispersive or diffractive optical elements for wavelength-dependent influencing of the wavefronts allows much more compact and flexible designs than previous approaches with imaging optical elements.
  • Preferred embodiments of the invention result from the subclaims 2 to 34 following the main claim. Uses according to the invention result from claims 35 to 38 and a method according to the invention and preferred variants of variants derive from claims 39 to 48.
  • the invention comprises a device which combines dispersive or diffractive optical elements with an interferometer with the coupling of individual spatial modes and with a detector which can measure the intensity of the resulting interference pattern at a plurality of spatial positions, and a method which it allows the spectrum of the incident light or directly measured values that can be derived from such a spectrum to be reconstructed from an interference pattern measured in this way.
  • the device according to the invention is designed in such a way that the interference patterns of different spectral components of the spectral range to be examined differ greatly from one another.
  • Such an interference pattern assigned to a specific spectral component is referred to below as the basic pattern.
  • the patterns can be viewed one-dimensionally or two-dimensionally.
  • An interference pattern generated by a device according to the invention is considered to be a superimposition of a number of different basic patterns.
  • the interference pattern is recorded by the detector by measuring the intensities at a large number of discrete spatial positions. An interference pattern is therefore always in the form of a fixed number of (measured) values. Accuracy and representable spatial frequencies follow from the sampling theorem.
  • an interference pattern is interpreted as a series of (measurement) values and thus in the context of linear algebra as a vector or in particular as an element of a sequence space of the corresponding dimension.
  • the basic patterns introduced above are initially interpreted as linearly independent basic vectors of this sequence space.
  • the method according to the invention is based on the possibility of determining the respectively required basic pattern for a device according to the invention either by calculation or by measurement.
  • the spectrum of the incident light can then be obtained by breaking down the interference pattern into these basic patterns.
  • the particular advantages of the device and method for the realization of high-resolution or very compact optical spectrometers result from the optical mono-mode coupling, which allows the translational invariance of the optical transformation to be dispensed with and thus a collimator to be dispensed with.
  • the device can therefore be implemented entirely without the use of imaging optical elements. This is possible in combination with the described methods, which use the fact that at least approximately a numerical inverse transformation of the interference signal measured at the detector to the sought spectrum can be found for almost any, sufficiently complicated optical transformations.
  • s be a spectrum represented by discrete spectral components of a certain intensity, ie as a vector with the components s n n: 1..N.
  • s comprises a certain spectral range of the optical spectrum, the individual components are spectrally close to the spectral resolution under consideration.
  • i be the interference pattern measured at the detector, i is therefore a vector which, for example, represents the individual elements of an array detector with the components i m m: 1..M
  • Te n t n
  • e n the unit vectors of the spectral components.
  • the optical transformation is an exact Fourier transformation
  • only one component of the expression F "1 (t n ) will be non-0, namely that which represents the respective spatial frequency and thus directly a spectral component of the spectrum.
  • the base vectors t n are not only linearly independent but also orthogonal and also form the unit vectors of the spatial frequencies, so for this special case the calculation from o is reduced to the Fourier transform of i.
  • optical transformation may be similar to those of a Fourier transform, or the optical transformation may be completely irregular, i.e. e.g. Form so-called “speckle patterns" ("granulation").
  • the first case can be represented by a grossly faulty optical Fourier transformation, for example generated by an optical arrangement according to the invention without a collimator and with very inexpensive optical elements. Due to the systematic generation, the basic patterns are still linearly independent but only approximately orthogonal.
  • the second case can be represented by an optical arrangement according to the invention with an interferometer based on a scratched piece of broken glass (extremely inexpensive).
  • the base vectors can be assumed to be statistically distributed here.
  • the method represents a correction, ie the poor quality of the optical transformation can be largely compensated for by an adapted reverse transformation.
  • the spectrum is determined by a purely statistical correlation of the measured values with the base vectors.
  • a high number of elements of the detector should be assumed, in particular it is favorable to choose M very much larger than N, for example by using a two-dimensional detector array.
  • the basic patterns are not linearly independent due to their statistical nature. Nevertheless, the correlation for large N shows good results. Very good results are obtained for very large M, because in this case, i.e. the statistical distribution of N base vectors in an M-dimensional space, the base vectors become at least approximately linearly independent.
  • correlation functions for the method can also be considered, in particular stochastic correlations.
  • a further calculation or refinement of the results by deconvolution is particularly advantageous if the selected method can be applied to a set of different transfer functions.
  • the arrangement according to the invention is used as a sensor, it may be advantageous to aim for the results of the calculations and not the spectrum, but rather the measured values sought.
  • the base vectors are then determined not by measuring spectral components but by recording spectra of the substances sought.
  • a base vector and thus a component of the result vector thus does not represent a single spectral component but directly the measured value sought, ie, for example, the concentration of a specific substance in accordance with an absorption spectrum.
  • This adaptive approach allows the implementation of optical sensors for a variety of applications.
  • the evaluation of the measurements by correlation with previously recorded basic patterns allows the desired quantities to be determined directly without having to go through an analysis of the optical spectrum.
  • the respective spectral components of the incident light and thus the spectrum can be determined by correlating the respective basic pattern with the recorded interference pattern.
  • the required set of basic patterns can be calculated.
  • the "perfect" interference patterns recorded are linearly independent (superposition of sinusoidal components) and the Fourier transformation represents an orthogonalization method.
  • the individual Fourier coefficients represent the spectral components of the measured spectrum.
  • a direct Fourier transformation of the patterns recorded with an arrangement according to the invention is pointless, but orthogonalization with respect to spectral components is possible after a suitable transformation of the recorded interference patterns. For this purpose, the relative path length difference of the partial beams brought to interference must be determined for each measuring point.
  • the interference pattern can be generated by dividing the amplitude of the incident light field with the aid of a semitransparent mirror or a suitable grating (optionally in more than two partial beams) and then superimposing the partial fields on the location of the detector.
  • All classical interferometers come into question here, which may be supplemented by dispersive or diffractive elements, for example: Michelson, Mach-Zehnder, Sagnac, Fabry-Perot or shear interferometers. Any arrangement that generates interference patterns with spatial periods that the respective detector can resolve is also suitable.
  • the spatial frequencies occurring at the detector can be selected independently of the wavelength range to be examined in each case.
  • the generation of the partial fields by dividing the wavefront is also possible, for example by means of a Fresnell biprism, other combinations of prisms or mirrors, with the help of irregularly shaped surfaces or also with the help of diffractive ones Elements.
  • the required spectral dispersion can in all cases be introduced by a suitable design of the beam splitter itself or by additional optical elements.
  • the detector can be moved through the interference pattern with a suitably small aperture (scan). It is also possible by moving other components of the device or with the help of an additional movable one Spiegel to record the different measuring points one after the other. This method is particularly suitable for extremely high-resolution measurements or in wavelength ranges for which no suitable spatially resolving detectors are available.
  • a suitable diode array or a CCD line is suitable as a spatially resolving detector.
  • Figure 1 shows an extremely compact arrangement according to claim 1, wherein the optical components are integrated in a monolithic glass block.
  • the light coupling (M) takes place directly from a monomode glass fiber into the block, so that the field initially develops as a spherical wave.
  • a diffraction structure (G) applied directly to the glass block divides the amplitude of the wave according to claim 2 into a diffracted and a reflected component, which each run to one of the mirrors (S1, S2) applied directly to the glass block.
  • the diffraction structure acts according to claim 27 both as a beam splitter and as a spectrally highly dispersive optical element which changes the wavefront of the diffracted beam in a spectrally dependent manner.
  • the detector (D) has a small spatial extension or has a suitable aperture and is located on a movable arm, shown with a pivot point (P).
  • the detector is moved by the light field and records its intensity at a number of spatial positions one after the other.
  • the arm is moved by means of an eccentric (X) which is driven by a motor (R).
  • a set of such measurements i.e. a set of measured values recorded at defined positions forms a pattern which can be evaluated with the aid of the methods according to claims 39-48.
  • An arrangement according to Figure 2 using a separate beam splitter (S) for dividing the amplitude of the waves according to claim 2 and two dispersive elements (G1, G2) in the arms of the interferometer is possible by a monomode coupling (M) according to claim 4.
  • An aperture diaphragm (A) as shown is advantageous.
  • Such an arrangement does not require Fourier transform optics or completely without imaging optical elements, since the translational invariance of the Fourier transform can be dispensed with.
  • the evaluation of the interference pattern which such an arrangement produces cannot therefore be carried out directly by means of a numerical Fourier transformation, but rather requires one of the methods presented in claims 39 to 48.
  • the arrangement shown in Figure 2 uses a spatially resolving detector (CCD) according to claim 9.
  • a phase modulator (P) according to claim 14 has a particularly advantageous effect, for example in the form of the piezo actuator symbolized in the figure.
  • a monomode coupling in particular also permits interferometric arrangements based on a division of the wavefront according to claim 3. In addition to dispensing with imaging optical elements, this also allows dispensing with a beam splitter as a discrete optical element.
  • Figure 3 shows an arrangement according to claims 1 and 3.
  • the prerequisite is a coupling (M), for example according to claim 4.
  • the coupled light field propagates from M as a spherical wave.
  • the mirror (S) has a suitable opening through which the coupled field can pass.
  • Part of the wave hits a diffraction grating (G1), another part hits a diffraction grating (G2), so the wavefront is divided.
  • G1 diffraction grating
  • G2 diffraction grating
  • An aperture diaphragm (A) as shown is advantageous.
  • the gratings deflect the light back onto the movable mirror (S) with the highest possible efficiency, where the wave fields are superimposed.
  • the movable mirror reflects the resulting field onto the detector (D) which, depending on the position of the mirror, can record the intensity of the field at a number of different positions.
  • phase modulator according to claim 14, for example in the form of the piezo actuator (P) shown.
  • the performance of the device and of the method described below can be significantly improved if the relative phase position of the partial beams can be suitably influenced.
  • This can be done, for example, by using a mirror which can be displaced linearly over a distance of the order of the wavelength, by means of which the relative phase position of the reflected light can be changed with great accuracy, or e.g. in the case of a shear interferometer or e.g. in the case of a grating with several spatial frequency components as a beam splitter by means of a suitable "lateral" displacement of the components.
  • the interferometric devices shown can also be designed or developed in such a way that the differences in the optical path lengths under which the partial beams are brought to interference differ by a degree introduced by the dispersive element or elements.
  • the interference is then limited to components of the incident light with a correspondingly high coherence length or small bandwidth.
  • An interference signal is only generated when the incident radiation shows coherence properties or autocorrelation properties in the region of the optical path length differences.
  • line spectra can be recorded selectively in this way. In this case, only spectrally narrow-band components of the incident radiation with correspondingly large coherence lengths contribute to the measured signal.
  • the arrangement has the particular advantage that the spectral resolution (spectroscopy) or bandwidth (data transmission) can be set independently of the line width to be selected (spectroscopy) or autocorrelation length (data transmission).
  • Figure 4 shows an extremely compact and inexpensive possibility of realizing an arrangement according to the invention.
  • a diffracting optical element (D) according to claim 11 is used in a function according to claim 27, in this case a diffuser with a granularity of a suitable size.
  • a prerequisite for operation is that the light field (M) is coupled in the form of only one or fewer spatial modes according to claims 4 to 6.
  • a suitable aperture diaphragm (A) as shown is advantageous.
  • the variant shown expediently has an imaging detector (CCD) according to claim 10.
  • the diffuser can be replaced by diffractive elements which can generate a highly structured interference field.
  • a variant of the Talbot or Lau effect can also be used, in particular the ability of certain structures to map themselves. If necessary, different interference fields can be generated by spatially displacing the coupling or displacing or tilting the diffuser according to claim 15.
  • This arrangement is advantageously operated with a very large number of measuring points for the interference field in combination with the statistical methods shown.
  • FIG. 5 shows an arrangement according to the invention according to claim 16 with this property.
  • the light field (M) must be coupled in according to one of claims 4 to 6 in order to generate recognizable interference fields.
  • a suitable aperture diaphragm (A) as shown is advantageous.
  • the resonator is formed according to claim 17 by the beam splitter (S) and a diffractive element (G) which simultaneously serves as a beam splitter via different diffraction orders.
  • the field is coupled into the resonator via the beam splitter (S), and the resulting interference field is coupled out towards the detector (CCD) via the diffractive element (G). Further multiple reflected partial beams also contribute to the interference.
  • multiplex gratings in addition to simple gratings on the one hand and complex diffraction structures on the other hand, multiplex gratings (superimposition of several spatial frequencies) or multiply divided gratings, for example as shown in Figure 6, are suitable diffractive element (G) in the form shown is realized by stripes lying next to one another with different lattice constants.
  • the part of the field reflected by the respective gratings (0th diffraction order) leaves the resonator, while the part of the light field diffracted by the gratings (provided a suitable wavelength is provided) initially remains in the resonator and partly again the diffractive element via the beam splitter (S) reached.
  • resonator The technical design of the resonator is of minor importance. In addition to simple resonators with only two components, all types of resonators, in particular ring cavities, are also possible.
  • a further embodiment according to the invention provides that the device has means for rotating the interferometer or means for changing or selecting the angle of incidence, which enable the spatial frequency or the spatial frequencies of the generated interference pattern to be set.
  • the wavelength range that the arrangement can detect without moving parts is given by the ability of the detector to detect the corresponding spatial frequencies in the interference pattern. It can be particularly advantageous for a technical implementation of the arrangement to select a wavelength range, i.e. in this case, the setting of the interferometer such that the spatial frequencies resulting for this wavelength range can be detected by the detector by rotating the interferometer as a whole or by a suitable change in the angle of incidence.
  • the interferometer itself does not need any movable elements, apart from the means that may be required for phase modulation, and can nevertheless be used for different wavelength ranges.
  • the components of the interferometer can be fixed against each other, which has an advantageous effect on the stability of the adjustment.
  • a prerequisite for the wavelength adjustment via the angle of incidence is that the angle at which the subfields are superimposed in the interferometer shows a suitable dependence on the angle of incidence. This is e.g. the case when the subfields are superimposed in mirror image, i.e. the subfields must be guided in an asymmetrical interferometer in this regard over a number of mirrors that is different by 1 in each case.
  • Figure 7 shows a particularly advantageous arrangement according to claim 30.
  • the light field is coupled in according to one of claims 4 to 6 (M).
  • the aperture diaphragm (A) limits the solid angle to avoid stray light.
  • the light field then strikes a diffractive structure according to claim 27 or 28 (diffraction grating), preferably designed as a grating or multiplex grating. Holographic optical elements can be used very advantageously at this point.
  • the reflected part of the field hits a mirror (S2), the diffracted part of the field hits another mirror (S1). Portions of the respective subfields are reflected back from the mirrors to the diffractive element and are superimposed there by partial reflection and diffraction to form two interference fields.
  • One of these interference fields reaches the detector (CCD) as described in claim 30.
  • the patterns recorded by the detector can then be processed numerically in the manner already shown. Other parts of the fields leave the arrangement unused.
  • the actuator (phase shifter) shown in one of the mirrors (S2) enables interference patterns to be recorded at different relative phase positions of the subfields.
  • a particularly advantageous combination is the arrangement shown in Figure 8.
  • an aperture diaphragm (A), mirror (S1, S2), a diffractive element (diffraction grating) and the detector (CCD) can be used.
  • the exit aperture limits the variability of the interference patterns that occur.
  • the diffractive element is a diffraction grating
  • the exit aperture can also restrict the wavelength range of the fields that can reach the detector.
  • the correlation of a measured interference pattern required for a measurement with the interference pattern known for a specific spectral component or a group of spectral components can very advantageously be immediate optically with the aid of a mask and, if appropriate, suitable phase modulation or other detuning of the interferometer.
  • the interference pattern of a spectral fingerprint with many spectral components can already be contained in a single mask.
  • the multiple recording of the interference pattern through the mask upstream of the detector with different relative phase positions of the partial beams shows a strong dependence of the respectively measured integrated total intensity of the signal on the relative phase position only for those spectral components of the incident light with the resulting interference patterns the mask correlates.
  • a direct optical correlation is far superior to numerical methods under favorable circumstances.
  • This design of the arrangement becomes particularly interesting when using a variable mask, such as an LCD screen (spatial light modulator, SLM).
  • a variable amplitude mask (SLM) which can represent different patterns for optical correlation, is relatively easy to implement, since the mask is no longer part of the actual interferometer.
  • the change in the relative phase position of the interfering subfields and the change in the spatial frequency or the spatial frequencies of the generated interference pattern are carried out jointly by moving at least one component of the device.
  • the rotation of one of the optical elements around a base P outside the beam path causes not only the change in the angle and thus the setting of the selected wavelength, but also a change in the optical path length and thus a modulation of the relative phase position.
  • the spectrally dispersive or diffractive element is a multiplex grating, a multiplex hologram, a holographic-optical element or a computer-generated hologram (CGH).
  • holographic elements can also be considered here, which can, for example, bend entire groups of different spectral lines at the same angle. This variant can be particularly favorable when using a detector that uses a mask to recognize patterns (optical correlation method).

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectrometry And Color Measurement (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)

Abstract

La présente invention concerne un dispositif et un procédé de spectroscopie optique, des capteurs optiques ainsi que l'utilisation dudit dispositif. L'objectif de cette invention est d'obtenir un dispositif à haute résolution spectrale avec, dans un même temps, des exigences comparativement faibles en termes de qualité des composants optiques. A cet effet, ce dispositif de spectroscopie optique comprend des moyens servant à la production d'une figure d'interférence, des moyens servant à l'injection du champ lumineux à examiner, lesquels moyens sont conçus de sorte que seul un mode spatial ou les modes spatiaux individuels de ce champ sont admis, ainsi qu'un détecteur pouvant capter l'intensité de la figure d'interférence produite dans une pluralité de positions spatialement différentes. Selon ladite invention, les fronts d'onde et/ou la direction de propagation d'au moins un des champs lumineux, intervenant dans ladite figure d'interférence, sont modifiés en fonction de la longueur d'onde par l'intermédiaire d'éléments optiques à dispersion ou diffraction spectrale. Cette invention concerne également un procédé permettant de déterminer le spectre optique et/ou des valeurs mesurées, codées et transmises par un spectre optique, par l'analyse de la figure d'interférence mesurée à l'aide d'un dispositif selon la présente invention.
EP02807594A 2002-07-15 2002-07-15 Dispositif et procede de spectroscopie optique, capteurs optiques et utilisation dudit dispositif Withdrawn EP1523663A1 (fr)

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US7466421B2 (en) 2008-12-16

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