WO2017092613A1 - 光学谐振腔用反射棱镜及其光学谐振腔和光谱测量仪 - Google Patents

光学谐振腔用反射棱镜及其光学谐振腔和光谱测量仪 Download PDF

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WO2017092613A1
WO2017092613A1 PCT/CN2016/107258 CN2016107258W WO2017092613A1 WO 2017092613 A1 WO2017092613 A1 WO 2017092613A1 CN 2016107258 W CN2016107258 W CN 2016107258W WO 2017092613 A1 WO2017092613 A1 WO 2017092613A1
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optical
light
reflective prism
optical path
reflective
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PCT/CN2016/107258
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English (en)
French (fr)
Inventor
邓文平
赵辉
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苏州谱道光电科技有限公司
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Priority to US15/780,210 priority Critical patent/US20180356569A1/en
Publication of WO2017092613A1 publication Critical patent/WO2017092613A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/04—Prisms
    • 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
    • G01J3/02—Details
    • G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
    • 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
    • G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
    • G02B17/08—Catadioptric systems
    • G02B17/0856—Catadioptric systems comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors
    • G02B17/086—Catadioptric systems comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors wherein the system is made of a single block of optical material, e.g. solid catadioptric systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/02—Constructional details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03—Cuvette constructions
    • G01N2021/0389—Windows
    • G01N2021/0396—Oblique incidence
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/15—Preventing contamination of the components of the optical system or obstruction of the light path
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry

Definitions

  • the present application relates to the field of spectroscopy, and in particular to a reflective prism for an optical resonant cavity and an optical resonant cavity and a spectrometer thereof.
  • spectroscopy studies the spectrum. Unlike other disciplines that focus on frequency, spectroscopy specializes in visible and near-visible light—a narrow fraction of the available spectral range, with wavelengths ranging from about 1 mm to 1 nm. Near visible light includes more than infrared and ultraviolet light. This range has far enough extensions on both sides of the visible range, but most lenses and mirrors made of common materials are still effective for this band, and it must always be considered that the optical properties of the material depend on the wavelength of the light.
  • Absorption spectroscopy can detect or identify a variety of different molecular types, especially simple molecular types such as water.
  • spectrometers offer high sensitivity, response times in the order of microseconds, immunity to interference, and limited interference from other molecular species than the species being studied. Therefore, absorption spectroscopy is a versatile method for detecting important micro/trace species.
  • the sensitivity and selectivity of this technique are optimized because the absorption capacity of the substance can be concentrated on a set of sharp spectral lines. This sharp spectral line in the spectrum can be used to distinguish from most interfering substances.
  • Spectroscopy can detect a few parts per million (ppm) of water in a high purity gas, and in some cases, a detection sensitivity level of a few parts per billion (ppb). Therefore, several spectroscopy methods have been used to monitor gas moisture content, including absorption measurements of conventional long path elements, photoacoustic spectroscopy, frequency modulation spectroscopy, and lumen laser absorption spectroscopy.
  • absorption measurements of conventional long path elements including absorption measurements of conventional long path elements, photoacoustic spectroscopy, frequency modulation spectroscopy, and lumen laser absorption spectroscopy.
  • these spectral methods have a variety of properties which make them impractical and difficult to use in practical industrial applications. Therefore, they are largely limited to laboratory research.
  • CRDS cavity ring-down spectroscopy
  • sensitivity is not ideal in a low absorbance state.
  • CRDS uses the average lifetime of photons in high-precision optical resonators as an observable measure of absorption sensitivity.
  • the optical cavity is formed by a pair of nominally identical, narrow-band, ultra-high reflective dielectric mirrors that are suitably configured to form a stable optical optical cavity.
  • a laser pulse is injected into the optical cavity through a mirror to experience an average lifetime, which is determined by the photon transit time, the length of the optical cavity, the absorption cross section and the concentration of the material, and the internal optics.
  • the cavity loss factor (mainly due to the negligible loss of diffraction loss, from the reflectivity of the frequency dependent mirror). Therefore, the measurement of light absorption is converted into a time decay measurement by a conventional power ratio measurement.
  • the ultimate sensitivity of the CRDS is determined by the amount of loss inside the optical cavity, and ultra-low loss optics produced using techniques such as fine polishing can minimize this loss.
  • an optical resonator is described in the patent document entitled "CN1397006A” entitled “Brussel angle prism reflector loop attenuation cavity spectrometer matching mode", which includes an optical resonator a first Brewster angle reflective prism of the total reflection surface, wherein one total reflection surface is a curved surface; a second Brewster angle reflection prism with a set of total reflection surfaces, the prism and the first reflection prism resonate along The cavity optical axes are collimated in a straight line; and optical elements for coupling light radiation into one of the first or second prisms.
  • the optical path of the optical cavity described above is a closed loop of the dual optical path, and the incident surface of the reflective prism of the optical resonant cavity also serves as an exit surface.
  • the geometry of the reflective prism of the optical resonant cavity is The size is limited to this, and it is difficult to miniaturize the device, so that the absorption loss of the light by the reflecting prism when passing through the reflecting prism is large, which affects the measurement sensitivity of the entire spectrometer.
  • the present application provides a reflective prism for an optical resonant cavity, an optical resonant cavity, and a spectrometer to miniaturize a reflective prism that can facilitate an optical resonant cavity, thereby facilitating reduction of material absorption loss of light.
  • the present application provides a reflective prism for an optical cavity having a sample measurement area, the reflective prism including a first surface for receiving light passing through the measurement area of the sample, a second face emitting light to the sample measurement area, a third face between the first face and the second face; the third face being for receiving light from the first face Total reflection to the second side.
  • the first surface and the second surface are Brewster surfaces
  • the third surface is a total internal reflection surface
  • At least one surface of the reflective prism is a curved surface.
  • the present application also provides an optical resonant cavity capable of receiving and emitting light and capable of internally transmitting the received light, the optical resonant cavity comprising:
  • An optical element comprising at least one reflective prism as described above;
  • the optical resonant cavity has a sample measurement area, and the sample measurement area can accommodate a sample to be tested.
  • the optical element can form a closed optical path.
  • the optical elements are at least three.
  • each of the optical elements is the reflective prism.
  • all of the reflective prisms include a first reflective prism, a second reflective prism, and a third reflective prism; a second side of the first reflective prism and a first side of the second reflective prism
  • the second surface of the third reflective prism is connected to the first surface of the first reflective prism through a second optical path, and the second surface of the second reflective prism and the third reflective prism are connected by a first optical path
  • the first surface is connected by a third optical path; an angle between the first optical path and the second optical path, an angle between the second optical path and the third optical path, and the third optical path
  • the angle between the first optical paths is greater than Where ⁇ B is the Brewster angle.
  • an angle between the third surface and the second surface is equal to an angle between the third surface and the first surface, which is equal to 0.5 times.
  • An angle between the first optical path and the second optical path is added by ⁇ B .
  • the method further includes: a matching optical element capable of matching an optical mode of the light source with an optical mode of the optical cavity.
  • At least one of the optical elements is rotatable and/or translatable.
  • the present application further provides a spectrometer comprising: the optical cavity of any of the above embodiments.
  • the optical resonant cavity provided by the present application uses a reflective prism by providing the first surface for receiving light in the optical resonant cavity and the second for emitting light in the optical resonant cavity.
  • a face, and the first face and the second face are mutually independent different faces, thereby ensuring that only a single spot of light is left on the face of the reflective prism, so that the side length of the reflective prism only needs to be larger than The size of the single spot can meet the requirements. Therefore, the reflective prism for the optical cavity provided by the present application can facilitate the miniaturization of the reflective prism of the optical cavity, thereby reducing the material absorption loss of the light.
  • Figure 1 is a schematic diagram of the propagation of a Gaussian beam along the Z axis
  • 2 is a schematic diagram of a Gaussian beam with a complex parameter q
  • Figure 3 is a schematic view of a two-mirror optical resonator composed of two mirrors
  • Figure 4 is a schematic view of a folded cavity in an optical resonant cavity
  • Figure 5 is a schematic diagram of an equivalent multi-element straight cavity of the folded cavity shown in Figure 4;
  • Figure 6 is a schematic view of an annular cavity in an optical resonant cavity
  • Figure 7 is a schematic diagram of an equivalent multi-element straight cavity of the annular cavity shown in Figure 6;
  • Figure 8 is a schematic view of a parallel plane cavity
  • Figure 9 is a schematic view of non-polarized incident light incident on the surface of the glass in air
  • FIG. 10 is a schematic view of a reflective prism provided by an embodiment of the present application.
  • FIG. 11 is a schematic view of a reflective prism having a curved surface provided by an embodiment of the present application.
  • FIG. 12 is a schematic view of a reflective prism having a curved surface according to another embodiment of the present application.
  • FIG. 13 is a schematic diagram of an optical resonant cavity provided by an embodiment of the present application.
  • FIG. 14 is a schematic diagram of an optical resonant cavity provided by an embodiment of the present application.
  • 15 is a schematic diagram of an optical resonant cavity provided by an embodiment of the present application.
  • 16 is a schematic diagram of an optical resonant cavity provided by an embodiment of the present application.
  • 17 is a schematic diagram of an optical resonant cavity provided by an embodiment of the present application.
  • FIG. 18 is a schematic view showing a lens disposed on an optical path of an optical element according to an embodiment of the present application.
  • FIG. 19 is a schematic view showing an optical element provided with a mirror according to an embodiment of the present application.
  • 20 is a schematic diagram of a spectrometer module provided by an embodiment of the present application.
  • the Gaussian beam is a special solution of the Helmholtz equation under the appreciating amplitude approximation, which can well describe the properties of the fundamental mode laser beam.
  • a schematic diagram of the propagation of a Gaussian beam along the z-axis is given in Figure 1.
  • Equation (1.1) gives the law of Gaussian beam propagation in space.
  • Equation (1.2) shows the beam width of the Gaussian beam
  • Equation (1.3) shows the isocratic radius of curvature of the Gaussian beam
  • Equation (1.4) shows the phase factor of the Gaussian beam
  • the Gaussian beam can be determined by any two of R(z), ⁇ (z), and z.
  • the complex parameter q is used to represent the Gaussian beam, as shown in equation (1.5).
  • ABCD is the element of the matrix M below:
  • Figure 3 shows a resonant cavity consisting of two mirrors.
  • the Gaussian beam present in the stabilizing cavity can only be self-reproducing, that is, the Gaussian beam is required to be equal to itself after a round trip in the cavity.
  • the formula (1.15) is a stable condition of a simple two-mirror cavity.
  • a folding cavity is formed.
  • the folded cavity can be expanded into a multi-component straight cavity for analysis.
  • the three-mirror folded cavity shown in FIG. 4 can be expanded into the thin lens sequence shown in FIG.
  • the method used in the above calculation of the two-mirror cavity can be used to calculate the stability conditions of the folded cavity, the difference being that the elements of the ABCD matrix are different.
  • the cavity in which the beam of light is transmitted along a polygonal closed optical path is referred to as an annular cavity.
  • the parameters of the beam q that can exist in the stable annular cavity should satisfy the self-reproduction condition around the circumference.
  • the surrounding matrix should be used for the annular cavity.
  • the annular cavity is expanded into a periodic thin lens sequence, and the mirror i is used as a reference, and the surrounding matrix is
  • the stability condition is
  • the fundamental mode Gaussian beam width at the mirror i is
  • the phase curvature radius of the Gaussian beam at the mirror i is
  • the waist width on the split arm is Taking the mirror i as the reference, the waist position is
  • the equivalent periodic thin lens sequence of the traveling wave (set in the direction of the mirror S1 ⁇ S2 ⁇ S3 ⁇ S4 ⁇ S1) is as shown in Fig. 7, thereby obtaining a surround matrix (1.16).
  • the mode of the laser is defined as the eigenstate of the electromagnetic field in the optical cavity. Different modes correspond to different field distributions and resonant frequencies.
  • the modes can be divided into longitudinal mode and transverse mode.
  • the longitudinal field stable field distribution characterized by the integer n is generally referred to as the longitudinal mode.
  • Different transverse modes correspond to different laterally stable light field distributions and frequencies.
  • Pattern matching means that the mode of the beam and the mode of the cavity need to meet the matching condition, that is, the radius and position of the waist spot of the beam coupled to the optical cavity completely coincide with the radius and position of the waist spot of the cavity.
  • Resonance conditions Taking the parallel plane cavity shown in Fig. 8 as an example, in order to form a stable oscillation in the cavity, it is required that the light wave is strengthened by the interference.
  • Total reflection When light passes from the first medium to the second medium with higher optical density, the light is refracted toward the normal direction. The light that enters the optically permeable medium from the optically dense medium is refracted away from the normal direction. There is an angle here called the critical angle ⁇ , so that for all incident angles greater than this critical angle, all rays will be reflected without refraction. This effect is called total internal reflection and this effect occurs inside the material where the optical density is larger than the outside of the interface.
  • Figure 9 depicts the non-polarized incident ray 12 incident on the glass surface 16 in air.
  • the refractive index n of the glass is generally 1.5.
  • the electric field vector of each wave train in the light can be decomposed into two components: one component is perpendicular to the plane of incidence in the figure and the other component is located in the plane of incidence.
  • the first component here represented by black dots, is the S-polarized component (derived from German senkrecht, meaning vertical); the second component, indicated by the arrow, is the P (parallel) polarization component.
  • the amplitudes of the two components are equal.
  • the angle of polarization (found by David. Brewster in the experiment, hence the name Brewster angle ⁇ B ), the reflection coefficient of this angle to the P-polarized component. Is 0. Therefore, the light 18 reflected from the surface of the glass, although low in light intensity, is of plane polarized light whose vibrating surface is perpendicular to the first side.
  • the P-polarized component at the polarization angle is totally refracted at an angle ⁇ r ; the S-polarized component is only partially refracted. It can be seen from Figure 9 that the ray 20 is partially polarized.
  • a prism is a type of refractive and reflective device.
  • An optical component that has one or more third faces on the same piece of glass is called a reflective prism.
  • FIG. 10 is a reflective reflector for an optical resonant cavity 102 for forming the optical resonant cavity 100.
  • the optical resonant cavity 100 has a measurement area 103, and the reflective prism is provided.
  • 102 has a first face 1021 for receiving light passing through the measurement area 103, a second face 1023 for emitting light to the measurement area 103, and the first face 1021 and the second face 1023 A third face 1022 between the third face 1022 is configured to totally reflect light received from the first face 1021 to the second face 1023.
  • the reflective prism 102 can form the optical resonant cavity 100. Specifically, the reflective prism 102 is used to form a closed optical path 101 within the optical resonant cavity 100.
  • the light from the light source is After entering the optical cavity, the light will partially emerge after a week of propagation in the optical cavity, which can be defined as an exit event.
  • the light corresponding to the outgoing light propagates again for one week, and then partially exits again, defined as a secondary emission event. If the exit position and direction of the outgoing light of one exit event and the second exit event are nominally completely coincident, it is indicated that the light satisfying the incident condition forms a closed optical path 101 in the resonant cavity.
  • incident light (P-polarized light) emitted from the outside is incident to the second surface 1023 of the first reflective prism P at a near Brewster angle, and the second surface 1023
  • the reflected light is incident on the second reflective prism 102 at Brewster's angle, and after being totally reflected inside the second reflective prism M, is emitted at Brewster's angle, and the transmitted light is in the same manner at the third reflective prism 102.
  • the light 101 transmitted from the third reflecting prism N is incident on the first surface 1021 of the first reflecting prism P at a near Brewster angle, the first surface 1021 reflects a part of the light and the other part transmits the light.
  • the signal of the outgoing event The partially transmitted light continues to propagate inside and between the reflective prisms 102 until it is again incident from the third reflective prism N to the first face 1021 of the first reflective prism P at a near Brewster angle, again, the first face 1021 reflects a part of the light, and the other part of the light is transmitted. This is the signal of the secondary emission event. Otherwise, if the signal of the secondary emission and the signal of the first exit are the same in the position and direction of the first surface 1021, Light that satisfies this incident condition forms a closed optical path within the optical cavity. Without considering the absorption loss, Fresnel loss, scattering loss, diffraction loss, etc.
  • the light rays that surround the closed optical path 101 include light that passes through the measurement area 103 and light that propagates within the reflective prism 102.
  • the reflective prism 102 may be disposed on a boundary of the measurement area 103 for accommodating the sample to be tested, thereby ensuring that light emitted by the reflective prism 102 can pass through the sample to be tested and be absorbed by the sample to be tested. .
  • the light may be P-polarized light.
  • the third face 1022 completes the incident operation, then the third face 1022 reflects the light to the second face 1023 of the current prism to complete the reflective operation, and the second face 1023 receives the light from the third face 1022
  • the light is refracted and sent to other optical components in the closed optical path 101.
  • each of the reflective prisms 102 sequentially performs an incident operation, a reflective operation, and an outgoing operation until the light can form a stable closed optical path 101.
  • the optical resonant cavity reflective prism 102 provided by the present embodiment is provided with the first surface 1021 for receiving light in the closed optical path 101 and for emitting light in the closed optical path 101.
  • the second surface 1023, and the first surface 1021 and the second surface 1023 are mutually independent different surfaces, and further It can be ensured that only a single spot is left on the surface of the reflective prism 102, which makes the side length of the reflective prism 102 only need to be larger than the size of a single spot, so that the optical cavity provided by the present embodiment is used.
  • the reflective prism 102 can facilitate the miniaturization of the reflective prism 102 of the optical resonant cavity 100, thereby facilitating the reduction of material absorption loss of light.
  • the reflective prism 102 is used to form the closed optical path 101.
  • the closed optical path 101 is formed by multiple reflections and refractions between optical elements in the optical resonant cavity 100, and is located in the closed optical path 101.
  • the light in the sample can be absorbed by the sample to be tested when passing through the sample to be tested.
  • the optical elements forming the closed optical path 101 may have various combinations. Specifically, for example, the optical element may include the reflective prism 102 and other kinds of reflective prisms 102; or the optical element may also include a mirror and The reflective prism 102; or the optical component includes only a plurality of the reflective prisms 102, which is not limited thereto.
  • the reflective prism 102 is only a part of the optical components forming the closed optical path 101, that is, the reflective prism 102 provided by the embodiment may be an optical component forming the closed optical path 101.
  • One of the elements may also be a plurality of elements forming the optical element of the closed optical path 101.
  • all of the reflective prisms 102 may cause the light to form the closed Light path 101.
  • the reflective prism 102 may be a triangular prism having a triangular cross section.
  • the prism 61 may be a trapezoidal cross section as a whole in order to facilitate miniaturization of the device and assembly with other optical components.
  • Each of the reflective prisms 102 has three mutually independent faces as the first face 1021, the third face 1022, and the second face 1023.
  • the first surface 1021 and the second surface 1023 may be opposite to each other, and the third surface 1022 may be located between the first surface 1021 and the second surface 1023.
  • a single of the reflective prisms 102 can also be an irregularly shaped prism, on which a plurality of faces can assume the function of a single of the first face 1021, the second face 1023, and the third face 1022.
  • the same can be an embodiment of the present application.
  • the shape of each of the reflective prisms 102 may be the same or different, and only each of the reflective prisms 102 and the other reflective prisms 102 can be The light constitutes the closed optical path 101, and the present application is not limited thereto.
  • the reflective prism 102 is located at a boundary of the measurement region 103 in the optical resonant cavity 100 .
  • the measurement region 103 may be provided with a sample to be tested, and the measurement region includes at least light passing through the closed optical path. The area, which in turn ensures that the light passes through the sample to be tested.
  • the sample to be tested may be a solid, a gas, a liquid, or may be a liquid crystal or a biological tissue.
  • the reflective prism 102 may have a surface in contact with the sample to be tested.
  • the first surface 1021 needs to be in direct contact with the sample to be tested, since the first surface 1021 needs to pass through the sample to be tested and enters the first surface 1021.
  • the second surface 1023 also needs to be in contact with the sample to be tested.
  • the reflective prism 102 is a prism having a trapezoidal cross section, the reflective prism 102 has a surface that does not participate in optical effects, and the surface is also placed in the sample to be tested.
  • the reflective prism 102 may be made of glass.
  • suitable materials are: fused quartz, sapphire, calcium fluoride, diamond, yttrium aluminum garnet (YAG), silicon nitride (Si). 3 N 4 ), zirconium oxide (ZrO 2 ), aluminum oxide (Al 2 O 3 ), hafnium oxide (HfO 2 ), etc.
  • the material of the reflective prism 102 can also be other in the light wave frequency range. Transparent medium, this application is not limited to this.
  • the reflective prism 102 made of the material is placed in the measurement work, and the second surface 1023 and the first surface 1021 of the material are not subjected to the sample to be tested in the measurement area 103 and the sample to be tested. Damaged by impurities.
  • the second surface 1023 and the first surface 1021 may also be attached with a material that is chemically inert to the sample to be tested and impurities in the sample to be tested.
  • the first surface 1021 is configured to receive light in the closed optical path 101 and refract it to the third surface 1022 of the current reflective prism 102.
  • the incident angle of the light received by each of the first faces 1021 may be the Brewster's angle.
  • the first surface 1021 may be plated with a high permeability film, thereby further reducing the loss of light while reducing the occurrence of stray light.
  • the incident angle of the light received by the first surface 1021 needs to be a non-Brewster angle, that is, ⁇ B + ⁇ , ⁇ ⁇ 0.
  • the light emitted from the first surface 1021 can enter the detector, and the physicochemical properties of the sample to be tested can be obtained by analyzing the light.
  • the first surface 1021 may be a Brewster surface, that is, an incident angle of light incident on the first surface 1021 is a Brewster angle or a near Brewster angle, and the incident angle is near cloth. At the Brewster angle, ⁇ is close to zero.
  • the second face 1023 is for receiving light from the third face 1022 of the current reflective prism 102 and refracting it to other optical elements in the closed optical path 101.
  • the light received by each of the second faces 1023 is refracted and the angles may be Brewster's angles.
  • the second surface 1023 may be plated with a high permeability film, thereby further reducing the loss of light while reducing the occurrence of stray light.
  • the angle of incidence of the light received from the light source on the second side 1023 is a non-Brewst angle, i.e., ⁇ B + ⁇ , ⁇ ⁇ 0.
  • the light received from the light source passes through the reflected light of the second surface 1023 and overlaps with the light path of the light refracted by the second surface 1023.
  • the second surface 1023 may be a Brewster surface, that is, an incident angle of light incident on the second surface 1023 is a Brewster angle or a near Brewster angle, and the incident angle is near cloth. At the Brewster angle, ⁇ is close to zero.
  • the third surface 1022 is configured to receive the light from the first surface 1021 and totally reflect it to the second surface 1023.
  • the third face 1022 can be a total internal reflection surface.
  • the third surface 1022 may be plated with an internal reflection film to minimize the loss of light during propagation.
  • the number of the third faces is not fixed, and may be one or plural.
  • the third surface 1022 can be away from the detection area, that is, away from the sample to be tested; the second surface 1023 , the first surface 1021 and the The surface participating in the optical action can be in direct contact with the sample to be tested. With such an arrangement, the third surface 1022 is not affected by the sample to be tested and the impurities in the sample to be tested. Thus, the environmental adaptability of the optical resonant cavity 100 provided by the present embodiment can be greatly improved.
  • At least one of the first surface 1021, the second surface 1023, and the third surface 1022 may be a curved surface.
  • at least one of the first surface 1021, the second surface 1023, and the third surface 1022 may be a curved surface.
  • the curved surface can ensure that the closed optical path 101 formed by the light is more stable. In order to further correct the astigmatism caused by the oblique incidence of light in the closed optical path 101, the astigmatism condition needs to be satisfied between the curvature of the curved surface and the light.
  • at least one of the first surface 1021 , the second surface 1023 , and the third surface 1022 may be planar or Not a surface.
  • the curved surface may be formed by optically processing at least one of the first surface 1021 , the second surface 1023 , and the third surface 1022 .
  • the optical processing may be physical processing, such as sanding, polishing, etc., on at least one of the first face 1021, the second face 1023, and the third face 1022.
  • the third surface 1022 can be processed into a curved surface by taking FIG. 11 as an example.
  • the curved surface may further be the lens 70 and the first surface 1021, the second surface 1023, and the third surface 1022 by an optical glue matching the refractive index coefficient. At least one face is glued to form.
  • the refractive index of the optical glue may be approximately equal to the refractive index of the curved surface.
  • the refractive index of the lens 70 and the reflective prism 102 may be the same or different, and the present application is not limited thereto.
  • the curved surface may be formed by optically contacting the lens 70 with at least one of the first surface, the second surface, and the third surface.
  • the optical contact is to smooth one surface of the lens 70 and at least one of the first surface, the second surface and the third surface, and then press and contact the two, thereby passing between the molecules Suction combines the lens 70 with the reflective prism 102.
  • the surface of the reflective prism 102 may further have an emitting portion 1025 .
  • the receiving portion 1024 can receive light from the light source to maintain the formation of the closed optical path 101. Specifically, for example, the light is emitted from the light source to the receiving portion 1024.
  • the receiving portion 1024 is located on one surface of the reflective prism 102, which may be the contact of the received light with the surface on which it is located.
  • the size of the receiving portion 1024 depends on the size of the spot formed by the received light on the surface on which it is located. Of course, the size of the receiving portion 1024 is not less than the size of the spot formed by the received light on its surface.
  • the emitting portion 1025 can emit light to the detector to the detector, and the detector calculates the physical and chemical properties of the sample to be tested by receiving the light.
  • the emitting portion 1025 is located on one surface of the reflective prism 102, and may be a contact of the emitted light with the surface on which it is located.
  • the size of the emitting portion 1025 depends on the size of the spot formed by the emitted light on the surface on which it is emitted. Of course, the size of the emitting portion 1025 is not less than the size of the spot formed by the emitted light on the surface on which it is emitted.
  • the receiving portion 1024 and the emitting portion 1025 are two portions that do not overlap, thereby preventing the light source from overlapping with the detector position. Meanwhile, in actual use, it is considered that the optical path is reversible, and the positions of the receiving portion 1024 and the emitting portion 1025 may be interchanged, and the position of the light source and the detector may be reversed at this time.
  • the receiving portion 1024 and the emitting portion 1025 may be located on different faces of the reflective prism 102. Since the receiving portion 1024 and the emitting portion 1025 are located on different faces, the positions of the light source and the detector can be flexibly set, thereby facilitating manufacture and assembly.
  • the receiving portion 1024 may be located on the second surface 1023, and the emitting portion 1025 may be located on the first surface 1021.
  • the second face 1023 having the receiving portion 1024 can receive light from the light source and reflect the light, and can also receive and refract light from the third face 1022.
  • the refraction position of the second surface 1023 of the receiving portion 1024 may coincide with the position of the receiving portion 1024, thereby overlapping the reflected light of the second surface 1023 with the optical path of the refracted light, so that the light forms the closed optical path.
  • the first face 1021 having the emitting portion 1025 can receive light from other optical components and emit the light portion toward the detector while refracting the light portion to the third face 1022 to form a closure. Light path 101.
  • an embodiment of the present application further provides an optical resonant cavity 100 capable of receiving and emitting light and capable of internally transmitting received light, the optical resonant cavity including: an optical component, the optical The element comprises at least one reflective prism 102 as described in any of the above embodiments; a receiving portion 1024 for receiving light from a light source; an emitting portion 1025 for emitting light to the detector; the receiving portion 1024 and the emitting portion 1025 On the face of the optical element.
  • the optical element may be disposed on a boundary of the measurement area 103 for accommodating the sample to be tested, thereby ensuring that light between the two optical elements can pass through the sample to be tested and be absorbed by the sample to be tested .
  • the incident light may be P-polarized light.
  • the optical element When light propagates between the optical elements to the reflective prism 102, the optical element reflects light to the first face 1021 of the reflective prism 102, the first face 1021 refracting light and transmitting it to The third face 1022 of the current reflective prism 102 completes the incident operation, and then the third face 1022 reflects the light to the second face 1023 of the current prism to complete the reflective operation, and the second face 1023 refracts the light and transmits The first face 1021 of the next optical component is given to complete the exit operation.
  • Each of the optical elements sequentially performs an incident operation, a reflection operation, and an exit operation until the light forms a stable closed optical path 101.
  • the light When the light propagates between the optical elements, the light is emitted from the emitting portion 1025 to the detector, that is, the outgoing light is emitted.
  • the detector receives the emitted light and calculates to obtain a composition of the sample to be tested.
  • the optical element can form the light into the closed optical path 101, and the preferred closed optical path is in a resonant state, thereby increasing the optical path of the light within the optical resonant cavity 100.
  • the number of the optical elements is plural, which is distributed at the boundary of the measurement area 103.
  • the optical element may include only the reflective prism 102 to constitute the prism-type optical resonant cavity 100; or as shown in FIG. 14 and 17 includes a mirror and the reflective prism 102 to form a hybrid optical cavity 100; and may include other kinds of reflective prisms 102 and the reflective prism 102.
  • the present application is not limited thereto, and only the optical element can ensure that the light forms the closed optical path 101.
  • the optical element includes at least one of the reflective prisms 102.
  • the number of the reflective prisms 102 may not be limited.
  • the reflective prisms 102 may cooperate with other kinds of reflective prisms or mirrors to form light into the closed optical path 101; the reflective prisms 102 are When there are multiple times, the light can be formed into the closed optical path 101 between the reflective prisms 102 without being matched with other kinds of reflective prisms 102 or mirrors.
  • the plurality of reflective prisms 102 are plural, they can be used in combination with other types of reflective prisms 102 or mirrors, and the present application is not limited thereto.
  • the receiving portion 1024 can receive light from the light source to maintain the formation of the closed optical path 101. Specifically, for example, the light is emitted from the light source to the receiving portion 1024.
  • the receiving portion 1024 is located on one face of the optical element, which may be the contact of the received light with the surface on which it is located.
  • the size of the receiving portion 1024 depends on the spot formed by the received light on its surface. The size, of course, the size of the receiving portion 1024 is not less than the size of the spot formed by the received light on its surface.
  • the emitting portion 1025 can emit light to the detector, and the detector calculates the physical and chemical properties of the sample to be tested by receiving the light.
  • the emitting portion 1025 is located on one face of the optical element, which may be the contact of the emitted light with the surface on which it is placed.
  • the size of the emitting portion 1025 depends on the size of the spot formed by the emitted light on the surface on which it is emitted. Of course, the size of the emitting portion 1025 is not less than the size of the spot formed by the emitted light on the surface on which it is emitted.
  • the receiving portion 1024 and the emitting portion 1025 may be located on different faces of the optical component on different sides. It should be noted that the receiving portion 1024 and the emitting portion 1025 are two portions that are not coincident. To prevent the light source from overlapping the detector position. Of course, in the present embodiment, it is preferable that the receiving portion 1024 and the emitting portion 1025 are located on both faces of the optical element. In the preferred embodiment, since the receiving portion 1024 and the emitting portion 1025 are located on different faces, the positions of the light source and the detector can be flexibly set, thereby facilitating manufacture and assembly.
  • the receiving portion 1024 may be disposed on one of the second faces 1023 of all the reflective prisms 102, and the emitting portion 1025 may be disposed on one of the first faces 1021 of all the reflective prisms 102. on.
  • the second face 1023 having the receiving portion 1024 can receive light from the light source and reflect the light, and can also receive and refract light from the third face 1022 of the current reflective prism 102.
  • the refraction position of the second surface 1023 of the receiving portion 1024 may coincide with the position of the receiving portion 1024, and the reflected light of the second surface 1023 and the optical path of the refracted light may be superposed to facilitate the formation of the closed optical path 101 by the light.
  • the first face 1021 having the emitting portion 1025 can receive light from other optical components and emit the light portion toward the detector while refracting the light portion to the third face 1022 to form a closure. Light path 101.
  • the optical element may be at least three and each of the reflective prisms 102, and thus the second surface 1023 having the receiving portion 1024 and the portion having the emitting portion 1025
  • the first surface 1021 may be located on the same reflective prism 102 or on different reflective prisms 102, so that the positions of the light source and the detector can be flexibly set.
  • light passes through all of the reflective prisms 102 to form a closed optical path 101.
  • the reflective prisms 102 may be arranged in a non-linear manner, and in combination with the third surface 1022 and the second surface 1023 of the same reflective prism 102, the closed light path formed by the reflective prisms 102.
  • each reflective prism 102 is a single optical path closed propagation, ensuring that one surface of each reflective prism 102 only needs to bear the incident work or the outgoing work, and there is only one incident spot or an exit spot on the surface, so that the size of the face only needs to be not less than the incident spot. Or the size of the spot can be used to meet the requirements of use.
  • all of the reflective prisms 102 can be integrally designed in consideration of the high degree of integration of optical components, but if they are still functioning as a plurality of the reflective prisms 102, they are still protected by the present application. Program.
  • the first face 1021 is configured to receive light from the second face 1023 of the other optical component and refract it to the third face 1022 of the current reflective prism 102. Except for the first face 1021 having the emitting portion 1025, in all of the reflective prisms 102, the incident angle of the light received by each of the first faces 1021 may be a Brewster's angle. In order to ensure the light transmittance of the first surface 1021, the first surface 1021 may be plated with a high permeability film, thereby further reducing the loss of light while reducing the occurrence of stray light.
  • the angle of incidence of the light emitted by the first face 1021 having the emitting portion 1025 to the detector needs to be a non-Brewster angle, that is, ⁇ B + ⁇ , ⁇ ⁇ 0.
  • the emitted light is emitted from the first surface 1021 and enters the detector.
  • the first surface 1021 may be a Brewster surface, that is, an incident angle of light incident on the first surface 1021 is a Brewster angle or a near Brewster angle, and the incident angle is near cloth. At the Brewster angle, ⁇ is close to zero.
  • the second face 1023 is for receiving light from the third face 1022 of the current reflective prism 102 and refracting it to the first face 1021 of the other optical component. Except for the second surface 1023 having the receiving portion 1024, in all of the reflective prisms 102, the light received by each of the second faces 1023 may be angled by Brewster's angle after being refracted. . In order to ensure the light transmittance of the second surface 1023, the second surface 1023 may be plated with a high permeability film, thereby further reducing the loss of light while reducing the occurrence of stray light.
  • the incident angle of the light received from the light source on the second surface 1023 of the receiving portion 1024 is a non-Brewster angle, that is, ⁇ B + ⁇ , ⁇ ⁇ 0.
  • the reflected light of the incident light passing through the second surface 1023 coincides with the optical path of the light refracted by the second surface 1023.
  • the second surface 1023 may be a Brewster surface, that is, an incident angle of light incident on the second surface 1023 is a Brewster angle or a near Brewster angle, and the incident angle is near cloth. At the Brewster angle, ⁇ is close to zero.
  • the second surface 1023 having the receiving portion 1024 and the first surface 1021 having the emitting portion 1025 may be different surfaces of different reflective prisms 102, or may be the same reflective prism 102. Different surfaces, this application is not limited to this. Of course, in order to reduce the complexity of debugging during use, the second surface 1023 of the receiving portion 1024 and the first surface 1021 having the emitting portion 1025 may be different surfaces of the same reflective prism 102 as a preferred Implementation.
  • the third surface 1022 is configured to receive the light from the first surface 1021 and totally reflect it to the second surface 1023.
  • the third surface 1022 may be all internal. Reflective surface.
  • the third surface 1022 can be plated with an internal reflection film to minimize the loss of light during propagation.
  • the third surface 1022 is away from the detection area, that is, away from the sample to be tested; the second surface 1023, the first The face 1021 and the surface not participating in the optical action are in direct contact with the sample to be tested. With such an arrangement, the third surface 1022 is not affected by the sample to be tested and the impurities in the sample to be tested. Thus, the environmental adaptability of the optical resonant cavity 100 provided by the present embodiment can be greatly improved.
  • the optical component in the optical resonant cavity 100 , may include a first reflective prism P, a second reflective prism M, and a third reflective prism. N, the light can be formed into the closed optical path 101 by the first reflective prism P, the second reflective prism M, and the third reflective prism N.
  • the second surface 1023 has the receiving portion 1024 to receive light from a light source
  • the first surface 1021 has the emitting portion 1025 to emit light to the detector.
  • the second surface 1023 of the first reflective prism P and the first surface 1021 of the second reflective prism M are connected by a first optical path L1, that is, the light is emitted by the second surface 1023 of the first reflective prism P
  • the first optical path L1 reaches the first surface 1021 of the second reflective prism M.
  • the second surface 1023 of the third reflective prism N and the second surface 1023 of the first reflective prism P are connected by a second optical path L2, that is, the light is emitted by the second surface 1023 of the third reflective prism N.
  • the second optical path L2 reaches the second surface 1023 of the first reflective prism P.
  • the second surface 1023 of the second reflective prism M and the first surface 1021 of the third reflective prism N are connected by a third optical path L3, that is, the light is emitted by the second surface 1023 of the second reflective prism M.
  • the third optical path L3 reaches the first surface 1021 of the third reflective prism N.
  • an angle between the first optical path L1 and the second optical path L2, an angle between the second optical path L2 and the third optical path L3, and the third optical path L3 The angle between the first optical path L1 and the first optical path L1 is greater than Where ⁇ B is the Brewster angle.
  • ⁇ B is the Brewster angle.
  • an angle between the third surface 1022 and the second surface 1023 is equal to an angle between the third surface 1022 and the first surface 1021, which is equal to 0.5 times.
  • the angle L2 between the first optical path L1 and the second optical path is added by ⁇ B .
  • the shortest side length of the first surface 1021 and the second surface 1023 of the first reflective prism P depends on the spot size.
  • the length of the side ab should be at least larger than the incident light spot incident on the side ab.
  • the side ad does not bear the optical effect, but in consideration of the problem that the side ab reflects stray light, the angle of the side of the side ad can be set to the Brewster angle. To reduce stray light.
  • the lengths of the first optical path L1, the second optical path L2, and the third optical path L3 can be adjusted by translating the reflective prism 102 according to actual needs, and the relative positional relationship of the reflective prism 102 needs to satisfy the above formula. .
  • the lengths of the first optical path L1, the second optical path L2, and the third optical path L3 may be set to, for example, 10 cm to 100 cm; when the measurement area is
  • the lengths of the first optical path L1, the second optical path L2, and the third optical path L3 may be set to be, for example, on the order of millimeters or even smaller.
  • the triangle formed by the extension line of the first optical path L1, the second optical path L2, and the third optical path L3 may be an equilateral triangle, and the refractive index of the material of the reflective prism 102 N ⁇ 1.52, the shapes of the first reflective prism P, the second reflective prism M, and the third reflective prism N may be identical.
  • ⁇ cba ⁇ dcb ⁇ 86.66°, that is, the angle between the third surface 1022 and the second surface 1023 is approximately 86.66 degrees.
  • the triangle formed by the extension line of the first optical path L1, the second optical path L2, and the third optical path L3 may be an isosceles triangle and the first optical path L1
  • the second optical path L2 is the waist of the isosceles triangle
  • the refractive index of the material of the reflective prism 102 is n ⁇ 1.52.
  • an angle between the third surface 1022 and the second surface 1023 is approximately equal to 90 degrees.
  • the shape of the second reflective prism M and the third reflective prism N may be the same.
  • the second reflective prism M and the third reflective prism N can each be a reflective prism with a rectangular cross section, which is very convenient for design and processing, and effectively enhances the design freedom of the reflective prism 102. .
  • the triangle formed by the extension line of the first optical path L1, the second optical path L2, and the third optical path L3 may be an isosceles triangle and the first optical path L1
  • the second optical path L2 is the waist of the isosceles triangle
  • the refractive index of the material of the reflective prism 102 is n ⁇ 1.52.
  • the angle between the third surface 1022 and the second surface 1023 is approximately equal to 84.98 degrees.
  • the shape of the second reflective prism M and the third reflective prism N may be the same.
  • the first reflective prism P can be a reflective prism with a rectangular cross section, which is very convenient for design and processing, and effectively enhances the design freedom of the reflective prism 102.
  • the optical component may include Four of the reflective prisms, all of which may form the closed optical path.
  • the four reflective prisms may form a "mouth” shaped closed optical path as shown in FIG. 15 or a "Z" shaped circuit as shown in FIG.
  • the four reflecting prisms may also form an "8" shaped closed optical path as shown in FIG.
  • the shape and number of the reflecting prisms 102 are not limited to the above-mentioned several exemplary embodiments, and the three reflecting prisms can also form a "V" shaped closed optical path as shown in FIG. Therefore, other changes may be made by those skilled in the art in light of the essence of the technical application of the present application, but the functions and effects of the present invention are the same or similar to the present application, and should be covered by the present application.
  • the optical element may comprise only one of the reflective prisms 102.
  • the reflective prism 102 as a whole may have a notched ring shape.
  • the notch of the reflective prism 102 may be the measurement area, and the two circular faces at the notch are the first face 1021 and the second face 1023; the entire side surface of the reflective prism 102 is
  • the third surface 1022 further ensures that light is incident into the reflective prism 102 from one of the first surface 1021 and the second surface 1023 and occurs on the third surface 1022 in the closed optical path. After being reflected multiple times, it is emitted from one of the first surface 1021 and the second surface 1023.
  • the quality factor of the optical cavity 100 formed using the optical element can be expressed by a Q value, which is defined as the energy stored in the weekly period divided by the energy lost.
  • Q value which is defined as the energy stored in the weekly period divided by the energy lost.
  • the optical element can be rotated and/or translated, thereby controlling the Q value and coupling by rotating and/or translating the first reflective prism P to adjust the reflection loss.
  • the reflection loss of each glass surface depends on Fresnel's law, and the loss value is about 10 -4 ⁇ 2 , and ⁇ is the deviation from Brewster's angle.
  • the distance between the adjacent two optical elements can be adjusted by the translation of the optical element, thereby adjusting the lengths of the first optical path L1, the second optical path L2 and the third optical path L3.
  • one surface of at least one of the reflective prisms 102 of the optical element may be disposed.
  • the curved surface that is, at least one of the first surface 1021, the second surface 1023, and the third surface 1022 is a curved surface.
  • the curvature of the curved surface and the astigmatism condition between the beams must be satisfied. The knowledge of the applied optics and the curvature of the curved surface can be solved by means of optical design software.
  • the curved surface may be formed by optically processing at least one of the first surface 1021 , the second surface 1023 , and the third surface 1022 .
  • the optical processing may be physical processing, such as sanding, polishing, etc., on at least one of the first face 1021, the second face 1023, and the third face 1022.
  • the curved surface may also be an optical glue matched by a refractive index coefficient.
  • the lens is formed by gluing the lens 70 with at least one of the first surface 1021, the second surface 1023, and the third surface 1022.
  • the refractive index of the optical glue may be approximately equal to the refractive index of the curved surface.
  • the refractive index of the lens 70 and the reflective prism 102 may be the same or different, and the present application is not limited thereto.
  • the curved surface may be formed by optically contacting the lens 70 with at least one of the first surface, the second surface, and the third surface.
  • the optical contact is to smooth one surface of the lens 70 and at least one of the first surface, the second surface and the third surface, and then press and contact the two, thereby passing between the molecules Suction combines the lens 70 with the reflective prism 102.
  • the mode of the light beam and the mode of the optical cavity 100 need to satisfy the matching condition, that is, the waist spot radius and position of the light coupled to the optical optical cavity 100.
  • the waist radius and position of the optical cavity 100 completely coincide.
  • the condition of the pattern matching can be calculated by using the ABCD matrix described in the above general principle.
  • the optical resonant cavity 100 can include matching optical components that can match the light to the pattern of the optical resonant cavity 100.
  • the matching optical element is located in the measurement area 103 and/or is used to radiate light emitted by the light source (the optical radiation is coupled into or out of the optical resonant cavity in an evanescent wave manner, or in an evanescent wave manner)
  • the measurement sample contact is coupled to the receiving portion 1024, the matching optics comprising at least one lens 80 and/or at least one mirror 90.
  • the matching optical element has at least one non-planar shape including at least one of a spherical surface, a cylindrical surface, an ellipsoidal surface, a paraboloid, and a free curved surface.
  • the lens 80 may be located on one of the first optical path L1, the second optical path L2, and the third optical path L3.
  • the number of the lenses 80 may be one or more, and the matching lens 80 may be located at any position on the optical path.
  • the mirror 90 couples optical radiation to the receiving portion 1024.
  • the mirror 90 is capable of matching the light emitted by the light source to the pattern of the optical resonant cavity 100.
  • the mirror 90 is capable of incident light to the receiving portion 1024 at a near Brewster angle.
  • the mirror 90 may be disposed between the light source and the receiving portion 1024.
  • an embodiment of the present application further provides a spectrometer, including: as in the above embodiment.
  • Optical cavity 100 as described.
  • the measuring method used in the present invention is an optical method including, but not limited to, an absorption spectrum, a Raman spectrum, a scattering spectrum, a fluorescence, a photoacoustic spectrum, an excitation spectrum, a Fourier transform spectrum, an optical frequency comb, and the like.
  • the spectrometer can include a cavity ring-down spectrometer and a cavity-enhanced spectrometer, and the optical cavity 100 can be preferably applied to a cavity ring-down spectrometer and a cavity-enhanced spectrometer, or can be applied to In the fields of photoacoustic, Raman, scattering, excitation, fluorescence, etc.
  • the spectrometer may include a light source control module 200, a light source module 201, an external light path adjustment module 202, the optical resonant cavity 100, an optical resonant cavity monitoring module 203, an optical resonant cavity control module 208, a sample preprocessing module 204, and a photoelectric
  • the light source control module 200 is configured to control functions such as opening or closing, frequency modulation, current tuning, temperature tuning, and the like of the light source module 201.
  • the light source module 201 may have different forms according to the detection technology and the use requirements, including but not limited to a laser light source, a broadband light source, a combination of different frequency laser light sources, a combination of a laser light source and a broadband light source, and the like.
  • the external optical path adjustment module 202 is configured to change the polarization property of the light, the divergence angle of the light beam, the energy distribution of the light field, and the like, and feed back a signal to the light source control module 200, where the external light path adjustment module 202 includes but is not limited to a polarizing device. , optical coupling, cutting device, etc.
  • the optical resonant cavity 100 is an optical delay system for increasing the propagation path of light, increasing the optical path, and improving the measurement sensitivity of the system.
  • the optical resonant cavity 100 includes, but is not limited to, a multiple reflection chamber, an optical resonant cavity, and the like.
  • the optical resonant cavity 100 includes an optical component as described above.
  • the optical cavity monitoring module 203 is configured to monitor an operating state of the reflective cavity 101, a fault alarm, and an online real-time calibration of the equivalent absorption optical path of the optical resonant cavity 100, and provide a monitoring signal to the optical cavity control module 208.
  • the optical cavity control module 208 is configured to correct the relative positional relationship of the optical devices in the optical cavity 100 in real time according to the monitoring signal provided by the optical cavity monitoring module 203.
  • the optical cavity control module 208 includes but is not limited to at least one PZT or Other mechanical structures or devices having a translational rotation function, or a combination thereof, are implemented to change the relative positional relationship of the optics of the optical resonant cavity 100.
  • the sample pretreatment module 204 is used for pretreatment of a sample to be tested, including but not limited to heating the sample to be tested, filtering out moisture in the sample, filtering out other impurities in the sample that are not related to the measurement, Filter out dust, etc.;
  • the photodetection module 205 is configured to receive and detect an optical signal output by the optical resonant cavity 100, convert the optical signal into an electrical signal, perform filtering, amplification, analog-to-digital conversion, and the like of the signal.
  • the data acquisition and processing module 206 collects the converted photoelectric digital signals, and performs spectral signal processing such as averaging and concentration calculation.
  • the data and image output module 207 is configured to output data and image information of a sample, such as a spectral line, a molecular spectral absorption intensity, a concentration value, and the like. It should be noted that the data and image output module 207 is set to display information such as element concentration, and its form and structure are not limited.

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Abstract

一种光学谐振腔用反射棱镜及其光学谐振腔和光谱测量仪。光学谐振腔（100）具有样品测量区域（103），反射棱镜（102）包括用于接收穿过样品测量区域（103）的光线的第一面（1021）、用于向样品测量区域（103）发出光线的第二面（1023）、位于第一面（1021）和第二面（1023）之间的第三面（1022）；第三面（1022）用于接收自第一面（1021）的光线全反射至第二面（1023）。光学谐振腔用反射棱镜及其光学谐振腔和光谱测量仪能够有利于光学谐振腔的反射棱镜小型化，进而利于降低光线的材质吸收损耗。

Description

光学谐振腔用反射棱镜及其光学谐振腔和光谱测量仪
交叉参考相关引用
本申请要求2015年12月1日递交的申请号为201510862675.1、发明名称为“光学谐振腔用反射棱镜及其光学谐振腔和光谱测量仪”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光谱学领域，尤其涉及一种光学谐振腔用反射棱镜及其光学谐振腔和光谱测量仪。
背景技术
光谱学学科研究的是光谱。与关注频率的其他部分学科不同的是，光谱学专门研究可见光和近可见光——一个可以获得的光谱范围中很窄的一部分，该光谱的波长范围在约1毫米至1纳米之间。近可见光包括比红外线和紫外线。这个范围在可见光波段两侧都有足够远的延伸，但大部分由普通材料制成的透镜和反射镜仍对该光波段有效，必须经常考虑到材料的光学性能是依赖于光波长的。
吸收式光谱学可以探测或识别各种不同的分子类型，尤其是简单分子类型，比如水。同时，光谱测量仪提供了高灵敏度、微秒量级的响应时间、抗干扰能力，以及有限的来自除所研究物质种类以外的其他分子种类的干扰。因此，吸收式光谱作为一种探测重要微/痕量物质类别的通用方法。在气体状态下，由于物质的吸收能力能够集中于一组尖锐的光谱线上，使得这种技术的灵敏度和选择性均发挥到最佳状态。光谱中这种尖锐的光谱线可以用来与绝大多数的干扰物质进行区分。
在许多生产过程中，对流动气流中微量物质的浓度进行迅速、准确的测量和分析是十分必要的，因为污染物的浓度往往至关重要地影响成品的质量。例如，氮气N2、氧气O2、氢气H2、氩气Ar、氦气He用来制造集成电路，存在于这些气体中的杂质，比如水，即使只有十亿分之(ppb)几的含量水平也是有害的，它会减少集成电路合格品产量。因此，在需要高纯气体的半导体工业中，较高的灵敏度对生产者来说是非常重要的，借助于光谱学的高灵敏度性能能检测出水分杂质。在其它工业生产过程中，也有必要对各种各样的杂质进行检测。
光谱学可以在高纯气体中检测含量为百万分之(ppm)几的水份，在某些情况下，还能够获得十亿分之几(ppb)的检测灵敏度水平。因此，已有数种光谱学方法被用于监测气体含水量，包括：传统长通路元件[long optical path cells]的吸收测定、光声光谱学、频率调制光谱学以及内腔激光吸收光谱学。但是，如莱曼(Lehmann)在美国专利号5,528,040的专利中所述，这些光谱方法具有多种特性，这使得它们在实际工业应用中是不切实际的和难以使用的。因此，它们在很大程度上仅限于实验室研究。
然而，回路衰减光谱技术(CRDS，cavity ring-down spectroscopy)已成为一种重要的光谱技术被应用于科学研究、工业生产控制、大气微/痕量气体监测。作为光吸收测定技术，已证实CRDS优于在低吸光度状态下灵敏度不很理想的传统方法。CRDS把高精密光学谐振腔中的光子平均寿命作为吸收灵敏度的可观测量。
一般地，光学谐振腔由一对名义上相同的、窄带的、超高反射性介电反射镜形成，经适当配置形成一个稳定的光学光学谐振腔。一个激光脉冲通过一个反射镜射入光学谐振腔以经历一个平均寿命时间，该平均寿命决定于光子往返渡越时间(transit time)、光学谐振腔长度、吸收横截面和物质的浓度数量、内部光学谐振腔耗损因子(主要产生于当衍射损耗可忽略不计时，来自取决于频率的反射镜的反射率)。因此光吸收的测定由传统的功率比测量转化成了时间衰减测量。CRDS的最终灵敏度由光学谐振腔内部的损耗量值决定，使用诸如精细抛光的技术生产的超低损耗光学器件可以使这个耗损值减至最小。
由于目前尚不能制造出具有足够高反射率的反射镜，因此在应用高反射率介电反射镜的光谱领域内，CRDS的应用还有局限，这就大大限制了该方法在大部分红外线的、紫外线领域的使用。即使在有适当反射率的介电反射镜的领域，每组反射镜也只能在小波长范围内有效，一般仅几个百分点的波长范围片段。而且，许多介电反射镜的制造需要使用一些材料，这些材料会随时间而变质，尤其是当暴露在化学腐蚀环境中时。这都限制或阻止了CRDS的许多潜在应用。
为解决上述问题，专利号为“CN1397006A”名称为“基于布儒斯特角棱镜反射器回路衰减空腔光谱仪匹配模式”的专利文件中记载了一种光学谐振腔，该光学谐振腔包括带有一组全反射面的第一布儒斯特角反射棱镜，其中一个全反射面为曲面；带有一组全反射面的第二布儒斯特角反射棱镜，该棱镜与第一反射棱镜沿着谐振腔光轴准直排列成一条直线；以及用来把光辐射耦合进入第一或第二棱镜两者之一中的光学元件。
但是，上述光学谐振腔在使用过程中的光路为双光路闭环，光学谐振腔的反射棱镜中的入射面同时也作为出射面，为防止光路重叠，因此该光学谐振腔的反射棱镜的几何 尺寸受限于此而难以将装置小型化，造成光线在穿过反射棱镜时被反射棱镜的吸收损耗较大，影响整个光谱仪的测量灵敏度。
发明内容
鉴于现有技术的不足，本申请提供一种光学谐振腔用反射棱镜、光学谐振腔和光谱测量仪，以能够有利于光学谐振腔的反射棱镜小型化，进而利于降低光线的材质吸收损耗。
为达到上述目的，本申请提供一种光学谐振腔用反射棱镜，所述光学谐振腔具有样品测量区域，所述反射棱镜包括用于接收穿过所述样品测量区域的光线的第一面、用于向所述样品测量区域发出光线的第二面、位于所述第一面与所述第二面之间的第三面；所述第三面用于将接收自所述第一面的光线全反射至所述第二面。
作为一种优选的实施方式，所述第一面及所述第二面为布儒斯特面，所述第三面为全内反射面。
作为一种优选的实施方式，所述反射棱镜的至少一个面为曲面。
为达到上述目的，本申请还提供一种光学谐振腔，其能接收和发出光线，并能将接收到的光线在内部传播，所述光学谐振腔包括：
光学元件，所述光学元件包括至少一个如上任一所述的反射棱镜；
所述光学谐振腔具有样品测量区域，所述样品测量区域能容置有待测样品。
作为一种优选的实施方式，所述光学元件能形成闭合光路。
作为一种优选的实施方式，所述光学元件至少为三个。
作为一种优选的实施方式，每个所述光学元件均为所述反射棱镜。
作为一种优选的实施方式，所有所述反射棱镜包括第一反射棱镜、第二反射棱镜以及第三反射棱镜；所述第一反射棱镜的第二面与所述第二反射棱镜的第一面通过第一光路连接，所述第三反射棱镜的第二面与所述第一反射棱镜的第一面通过第二光路连接，所述第二反射棱镜的第二面与所述第三反射棱镜的第一面通过第三光路连接；所述第一光路与所述第二光路之间的夹角、所述第二光路与所述第三光路之间的夹角以及所述第三光路与所述第一光路之间的夹角均大于
Figure PCTCN2016107258-appb-000001
其中，θB为布儒斯特角。
作为一种优选的实施方式，每个所述反射棱镜中，所述第三面与所述第二面的夹角 等于所述第三面与所述第一面的夹角，等于0.5倍的所述第一光路与所述第二光路的夹角加上θB。
作为一种优选的实施方式，还包括：匹配光学元件，所述匹配光学元件能将光源的光学模式与光学谐振腔的光学模式相匹配。
作为一种优选的实施方式，至少一个所述光学元件能够旋转和/或平移。
为达到上述目的，本申请还提供一种光谱测量仪，其特征在于，包括：如上实施方式任一所述的光学谐振腔。
通过以上描述可以看出，本申请所提供的所述光学谐振腔用反射棱镜通过设有用于在光学谐振腔中接收光线的所述第一面以及用于在光学谐振腔中发出光线的第二面，且所述第一面与所述第二面为相互独立的不同面，进而可以保证光线在反射棱镜的面上仅留有单个光斑，这就使得所述反射棱镜的边长仅需要大于单个光斑的大小即可满足要求，所以本申请所提供的光学谐振腔用反射棱镜能够有利于光学谐振腔的反射棱镜小型化，进而利于降低光线的材质吸收损耗。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1是高斯光束沿Z轴传播示意图；
图2是复参数为q的高斯光束示意图；
图3是一种由两个反射镜组成的两镜光学谐振腔示意图；
图4是一种光学谐振腔中的折叠腔示意图；
图5是图4所示折叠腔的等效多元件直腔示意图；
图6是一种光学谐振腔中的环形腔示意图；
图7是图6所示环形腔的等效多元件直腔示意图；
图8是一种平行平面腔示意图；
图9是非偏振入射光线在空气中入射到玻璃表面的示意图；
图10是本申请一个实施方式所提供的反射棱镜示意图；
图11是本申请一个实施方式所提供具有曲面的反射棱镜示意图；
图12是本申请另一个实施方式所提供的具有曲面的反射棱镜示意图；
图13是本申请一个实施方式所提供的光学谐振腔示意图；
图14是本申请一个实施方式所提供的光学谐振腔示意图；
图15是本申请一个实施方式所提供的光学谐振腔示意图；
图16是本申请一个实施方式所提供的光学谐振腔示意图；
图17是本申请一个实施方式所提供的光学谐振腔示意图；
图18是本申请一个实施方式所提供的光学元件的光路上设有透镜的示意图；
图19是本申请一个实施方式所提供的光学元件设有反射镜的示意图；
图20是本申请一个实施方式所提供的光谱测量仪模块示意图。
具体实施方式
为了使本技术领域的人员更好地理解本申请中的技术方案，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动的前提下所获得的所有其他实施例，都应当属于本发明保护的范围。
一、一般原理
下面将给出与本发明有关的光学的一般原理的综述导论。此综述导论将提供一个背景知识，以便对本发明有一个完整的理解。
A：高斯光束
高斯光束是亥姆霍兹方程在缓变振幅近似下的一个特解，它可以很好的描述基模激光光束的性质。图1中给出了高斯光束沿z轴传播的示意图。
式(1.1)给出了高斯光束在空间传播的规律。
Figure PCTCN2016107258-appb-000002
其中，R(z)、ω(z)、Ψ的表达式如下所示：
Figure PCTCN2016107258-appb-000003
R(z)＝Z0(z/Z0+Z0/z)          (1.3)
Ψ＝tan-1(z/Z0)          (1.4)
式(1.2)表示了高斯光束的束宽，式(1.3)表示了高斯光束的等相面曲率半径，式(1.4)表示了高斯光束的相位因子，其中
Figure PCTCN2016107258-appb-000004
高斯光束由R(z)、ω(z)、z中的任意两个即可确定，一般用复参数q表示高斯光束，如式(1.5)所示。
Figure PCTCN2016107258-appb-000005
高斯光束复参数q通过变换矩阵
Figure PCTCN2016107258-appb-000006
的光学系统的变换遵守ABCD定律：
Figure PCTCN2016107258-appb-000007
如图2所示，如果复参数为q1的高斯光束顺次通过变换矩阵为：
Figure PCTCN2016107258-appb-000008
的光学系统后变为复参数为q的高斯光束，此时ABCD定律亦成立，但其中ABCD为下面矩阵M的诸元：
M＝Mn…M2M1                (1.8)
B：光学谐振腔
稳定的光学谐振腔是指可使高斯光束的复参数q在传播一个周期后(往返一周或环绕一周)满足自再现条件，即q＝q(T)或腔内存在着高斯分布的自再现模。所以光学谐振腔具有两个特点：1、谐振腔的尺寸远大于光波的波长；2、一般为开腔。
以下给出了根据ABCD定律计算常见光学谐振腔的稳定性条件的计算方法。需要说明的是，ABCD定律并不是唯一的计算方法，例如也可用解析的方法进行计算。
1、简单的两镜谐振腔
图3所表示的是由两个反射镜组成的谐振腔，在稳定腔内存在的高斯光束只能是自再现的，即要求高斯光束在腔内往返传输一周后等于它自身。
如图3所示，以镜1为参考，往返一周矩阵为，其中
Figure PCTCN2016107258-appb-000009
Figure PCTCN2016107258-appb-000010
设q1为镜1上的初始高斯光束的复参数，经过往返传输一周后的复参数为q，稳定腔的自再现条件要求，q＝q1。
由ABCD定律
Figure PCTCN2016107258-appb-000011
得到：
Figure PCTCN2016107258-appb-000012
结合(1.5)式，式(1.11)中±号的选取应保证使
Figure PCTCN2016107258-appb-000013
为负值，即保证束宽平方为正值。
其中：
Figure PCTCN2016107258-appb-000014
将(1.9)、(1.12)代入(1.11)得到：
Figure PCTCN2016107258-appb-000015
R1＝ρ1              (1.14)
为使式(1.13)保持为正值，需满足式(1.15)
0<g1g2<1                (1.15)
其中，所述公式(1.15)即为简单的两镜谐振腔的稳定性条件。
2、折叠腔
如图4所示当使用反射镜将光路折叠后，就构成折叠腔。折叠腔可以展开为多元件直腔来进行分析。例如，以镜S1为参考，图4所示的三镜折叠腔可以展开为图5所示的薄透镜序列。这样，上述计算两镜谐振腔的中所使用的方法可用来计算折叠腔的稳定性条件，其区别只是ABCD矩阵的诸元不同。
3、环形腔
如图6所示，腔内光束沿以多边形闭合光路传输的腔称为环形腔。在高斯光束近似下，稳定环形腔内能够存在的光束q参数应当满足环绕一周自再现条件，计算中对环形腔应当使用环绕矩阵。
分别取镜1、2、3、4为参考面，将环形腔展开为周期性薄透镜序列，设以镜i为参考，环绕矩阵为
Figure PCTCN2016107258-appb-000016
则：稳定条件为|A+D|<2；镜i处基模高斯光束束宽为
Figure PCTCN2016107258-appb-000017
镜i处高斯光束等相位曲率半径为
Figure PCTCN2016107258-appb-000018
分臂上的束腰宽度为
Figure PCTCN2016107258-appb-000019
以镜i为参考束腰位置为
Figure PCTCN2016107258-appb-000020
例如，以镜S1为参考，行波(设为沿镜S1→S2→S3→S4→S1方向)的等效周期性薄透镜序列如图7所示，由此得到环绕矩阵(1.16)
Figure PCTCN2016107258-appb-000021
由此可得出环形腔的稳定性条件及高斯光束的相关参数。
C：激光的模式、模式匹配、谐振条件
激光的模式定义为光学谐振腔内电磁场可能存在的本征态，不同的模式对应不同的场分布和谐振频率，模可以分为纵模和横模。通常把由整数n所表征的腔内纵向的稳定场分布称为纵模。同时，与电磁场传播方向垂直的面内也存在着稳定的场分布，此为横模。不同的横模对应于不同的横向稳定光场分布和频率。
模式匹配是指光束的模式与谐振腔的模式需满足匹配条件，即耦合到光学谐振腔的光束的腰斑半径及位置与谐振腔的腰斑半径及位置完全重合。
谐振条件：以图8所示的平行平面腔为例，为了能在腔内形成稳定的振荡，要求光波因干涉得到加强。干涉的条件是光波在腔内沿轴线方向往返一周产生的相位差为2π的整数倍：Δφ＝2πm，由光程差和相位差的关系得：
Figure PCTCN2016107258-appb-000022
得到L＝q(λq/2)(光腔的驻波条件)，用频率表示为νq＝(c/2L)q，此式称为谐振条件，νq为谐振频率。
D：全反射
全反射：光线从第一媒质射向光学密度更大的第二种媒质时，光线会朝靠近法线方向折射。从光密媒质射入光疏媒质的光线则远离法线方向折射。这里存在一个角，称为临界角β，因此，对于所有的入射角大于这个临界角的情况，所有的光线都将反射，而不发生折射。这种效应称为全内反射，并且这个效应发生在光学密度比界面外部大的材料内部。
E：布儒斯特定律
布儒斯特定律：图9描述了非偏振入射光线12在空气中入射到玻璃表面16。玻璃的折射率n一般为1.5。光线中每一个波列的电场矢量可分解为两个分量：一个分量与图中入射平面垂直，另一个分量位于入射平面内。第一个分量，这里用黑点表示，为S偏振分量(源于德语senkrecht，意为垂直)；第二个分量，用箭头表示，为P(平行)偏振分量。平均来说，对于完全非偏振光线，这两个分量的振幅是相等的。
对于玻璃或其他介电材料，有一个特殊入射角，称为偏振角(由David.Brewster在实验中发现，因此也称为布儒斯特角θB)，这个角度对P偏振分量的反射系数为0。因此，从玻璃表面反射的光线18，尽管光强度低，但属于平面偏振光，它的振动面垂直于第一面。在偏振角处的P偏振分量以角度θr全部折射；S偏振分量只发生部分折射。由图9可以看出光线20是部分偏振光。
F：反射棱镜
棱镜是一种折射和反射类型的装置。把一个或多个第三面做在同一块玻璃上的光学零件叫做反射棱镜。如常见的直角棱镜、等腰棱镜、角锥棱镜、立方棱镜等。
二、本申请的光学谐振腔用反射棱镜、光学元件及其光学谐振腔和光谱测量仪
请参阅图10，为本申请一个实施方式所提供的一种光学谐振腔用反射棱镜102，其用于形成所述光学谐振腔100，所述光学谐振腔100具有测量区域103，所述反射棱镜102具有用于接收穿过所述测量区域103的光线的第一面1021、用于向所述测量区域103发出光线的第二面1023、位于所述第一面1021与所述第二面1023之间的第三面1022，所述第三面1022用于将接收自所述第一面1021的光线全反射至所述第二面1023。
所述反射棱镜102可以形成所述光学谐振腔100，具体地，所述反射棱镜102用于在所述光学谐振腔100内形成闭合光路101。在测定样品过程中，把光源发出的光线入 射进光学谐振腔，在光学谐振腔内传播一周后光线会部分出射，此时可以定义为一次出射事件。与出射光相对应的光线再次传播一周，而后再次部分出射，定义为二次出射事件。如果一次出射事件和二次出射事件的出射光的出射位置和方向名义上完全重合，则说明满足该入射条件的光在谐振腔内形成了闭合光路101。
可以以图13所示为例，在图13中，从外部发射过来的入射光(P偏振光)以近布儒斯特角入射至第一反射棱镜P的第二面1023，该第二面1023所反射的光以布儒斯特角入射至第二反射棱镜102，在第二反射棱镜M的内部经过全反射后以布儒斯特角出射，透射光以同样的规律在第三反射棱镜102传播，从第三反射棱镜N透射的光线101以近布儒斯特角入射至第一反射棱镜P的第一面1021，该第一面1021将一部分光线反射出去，另一部分光线透射，此为一次出射事件的信号。该部分透射的光线继续在反射棱镜102内部及之间传播，直至从第三反射棱镜N再次以近布儒斯特角入射至第一反射棱镜P的第一面1021，同样的，该第一面1021将一部分光线反射出去，另一部分光线透射，此为二次出射事件的信号，其余类推，如果二次出射的信号和一次出射的信号在第一面1021上的位置和方向上相同，则说明满足该入射条件的光在光学谐振腔内形成了闭合光路。在不考虑介质的吸收损耗、菲涅尔损耗、散射损耗、衍射损耗等的情况下，理论上光可以完成无限次的往复循环过程，实际中由于各种损耗的存在，循环的次数是有限的。同时，在图13中也可以看出，围成闭合光路101的光线包括穿过测量区域103的光线以及在所述反射棱镜102内传播的光线。
所述反射棱镜102可以设置于用于容纳待测样品的测量区域103的边界上，进而保证位于由所述反射棱镜102发出的光线可以穿过所述待测样品并被所述待测样品吸收。所述光线可以采用P偏振光。进行测量工作时，光线在闭合光路101中传播至所述反射棱镜102时，所述第一面1021接收来自闭合光路101中其他光学元件的光线后将光线通过折射并发送至当前反射棱镜102的所述第三面1022以完成入射工作，然后该第三面1022将光线反射给当前棱镜的所述第二面1023以完成反射工作，该第二面1023接收来自所述第三面1022的光线并将光线折射后发送给闭合光路101中的其他光学元件。当所述反射棱镜102为多个时，每个反射棱镜102顺次完成入射工作、反射工作、出射工作直至可以将光线形成稳定的闭合光路101。
通过以上描述可以看出，本实施方式所提供的所述光学谐振腔用反射棱镜102通过设有用于在闭合光路101中接收光线的所述第一面1021以及用于在闭合光路101中发出光线的第二面1023，且所述第一面1021与所述第二面1023为相互独立的不同面，进而 可以保证光线在反射棱镜102的面上仅留有单个光斑，这就使得所述反射棱镜102的边长仅需要大于单个光斑的大小即可满足要求，所以本实施方式所提供的光学谐振腔用反射棱镜102能够有利于光学谐振腔100的反射棱镜102小型化，进而利于降低光线的材质吸收损耗。
本实施方式中，所述反射棱镜102用于形成所述闭合光路101，所述闭合光路101由光线在光学谐振腔100中的光学元件之间经多次反射、折射而形成，位于闭合光路101中的光线穿过待测样品时能被待测样品吸收。形成所述闭合光路101的光学元件可以有多种组合，具体的，例如所述光学元件可以包括所述反射棱镜102以及其他种类的反射棱镜102；或者所述光学元件也可以包括有反射镜与所述反射棱镜102；或者所述光学元件仅包括有多个所述反射棱镜102，本申请并不以此为限。需要指出的是，所述反射棱镜102仅为形成所述闭合光路101的光学元件中的部分元件，即本实施方式所提供的所述反射棱镜102可以为形成所述闭合光路101的光学元件中的一个元件，也可以为形成所述闭合光路101的光学元件的多个元件，当然，所述反射棱镜102在数量为三个以上时，所有所述反射棱镜102就可以使光线形成所述闭合光路101。
所述反射棱镜102形成整体可以为横截面为三角形的三角棱镜，为便于装置的小型化以及与其他光学元件的装配，所述反射棱镜102整体也可以为横截面为梯形的棱台。每个所述反射棱镜102上具有三个互相独立的面为所述第一面1021、所述第三面1022、所述第二面1023。其中，所述第一面1021与所述第二面1023可以相对设置，所述第三面1022可以位于所述第一面1021与所述第二面1023之间。
当然，单个所述反射棱镜102也可以为不规则形状的棱镜，其上的多个面可以承担单个所述第一面1021、所述第二面1023、所述第三面1022的作用，这同样可以为本申请的一个实施方式。需要指出的是，所述反射棱镜102的数量为多个时，每个所述反射棱镜102的外形可以相同也可以不同，只需每个所述反射棱镜102与其他所述反射棱镜102能够将光线组成闭合光路101即可，本申请并不以此为限制。
请参阅图13，所述反射棱镜102位于光学谐振腔100中测量区域103的边界，所述测量区域103可以设置有待测样品，所述测量区域至少包括所述闭合光路中的光线穿过的区域，进而保证光线有效穿过待测样品。所述待测样品可以为固体、气体、液体，也可以为液晶、生物组织。所述反射棱镜102置于所述测量区域103边界时，所述反射棱镜102会存在与待测样品相接触的面。具体的，例如所述第一面1021由于需要光线穿过待测样品后进入所述第一面1021，所以所述第一面1021需要与所述待测样品直接接触， 同样的，所述第二面1023也需要与所述待测样品进行接触。在所述反射棱镜102为横截面为梯形的棱台时，所述反射棱镜102存在一个不参与光学作用的面，该面同样置于所述待测样品之中。
本实施方式中，所述反射棱镜102的制造材料可为玻璃，目前已知适用的材料有：熔凝石英、蓝宝石、氟化钙、金刚石、钇铝石榴石(YAG)、氮化硅(Si3N4)、氧化锆(ZrO2)、氧化铝(Al2O3)、二氧化铪(HfO2)等，当然，所述反射棱镜102的制造材料也可以为其他在光波频率范围内为透明的介质，本申请并不以此为限。由于上述种类材料具有化学惰性，该类材料制作的反射棱镜102置于在进行测量工作时，其第二面1023、第一面1021不会被测量区域103内的待测样品以及待测样品所含杂质所破坏。或者，所述第二面1023以及所述第一面1021也可以附着有对待测样品以及待测样品中的杂质具有化学惰性的材料。
本实施方式中，所述第一面1021用于在闭合光路101中接收光线并将其折射至当前反射棱镜102的所述第三面1022。在不参与到向闭合光路101外发出光线的工作时，在所述反射棱镜102中，每个所述第一面1021所接收的光线的入射角均可以为布儒斯特角。为保证所述第一面1021的透光率，所述第一面1021上可以镀设有高透膜，进而进一步降低光线的损耗，同时减少杂散光的出现。在参与到向闭合光路101外发出光线工作时，所述第一面1021所接收的光线的入射角需为非布儒斯特角，即θB+δ，δ≠0。所述光线由所述第一面1021发出后可以进入探测器，通过分析该光线即可得出待测样品的物化性质。较佳的，所述第一面1021可以为布儒斯特面，即光线入射至该第一面1021的入射角为布儒斯特角或近布儒斯特角，在入射角为近布儒斯特角时，δ接近于0。
所述第二面1023用于接收来自当前反射棱镜102的第三面1022的光线并将其折射发出至闭合光路101中的其他光学元件。在不参与到从闭合光路101外接收光线的工作时，在所述反射棱镜102中，每个所述第二面1023所接收的光线经折射发出后所呈角度可以均为布儒斯特角。为保证所述第二面1023的透光率，所述第二面1023上可以镀设有高透膜，进而进一步降低光线的损耗，同时减少杂散光的出现。在参与到从闭合光路101外接收光线的工作时，所述第二面1023上其从光源接收的光线的入射角为非布儒斯特角，即θB+δ，δ≠0。所述从光源接收的光线经所述第二面1023的反射光线与所述第二面1023所折射发出的光线光路重合。较佳的，所述第二面1023可以为布儒斯特面，即光线入射至该第二面1023的入射角为布儒斯特角或近布儒斯特角，在入射角为近布儒 斯特角时，δ接近于0。
本实施方式中，所述第三面1022用于接收来自所述第一面1021的光线并将其全反射给所述第二面1023。为降低光线在反射过程中的损耗，所述第三面1022可以为全内反射面。较佳的，所述第三面1022可以为镀设有内反射膜，进而最大程度的降低光线在传播过程中的损耗。当然，所述第三面的数量并不固定，其可以为一个也可以为多个。
以图13所示为例，在所述反射棱镜102中，所述第三面1022可以远离所述检测区域，即远离待测样品；所述第二面1023、所述第一面1021以及未参与光学作用的面可以与待测样品直接接触。通过此种设置，所述第三面1022不会受到待测样品以及待测样品中的杂质影响，如此，本实施方式所提供的光学谐振腔100的环境适应能力可以得到较大程度的提升。
本实施方式中，所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面可以为曲面。较佳的，所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面可以为曲面。所述曲面可以保证光线所形成的闭合光路101更加稳定。为了进一步校正光线在闭合光路101内斜入射时导致的像散，所述曲面的曲率和光线之间需要满足消像散条件。当然，作为一种优选的实施方式，也可以以如图13所示为基础，所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面可以为平面或不为曲面。
具体的，如图11所示，所述曲面可以为将所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面通过光学加工形成。所述光学加工可以为对所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面进行物理加工，例如打磨、抛光等。可以以图11为例将所述第三面1022加工成曲面。
进一步的，如图12所示，所述曲面还可以为通过折射率系数相匹配的光学胶合剂将透镜70与所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面胶合形成。所述光学胶合剂的折射率系数可以约等于所述曲面的折射率。所述透镜70与所述反射棱镜102的折射率可以相同，也可以不同，本申请并不以此为限。
此外，所述曲面还可以为将透镜70与所述第一面、所述第二面以及所述第三面中的至少一个面通过光学接触形成。所述光学接触为将透镜70的一面及所述第一面、所述第二面以及所述第三面中的至少一个面打磨光滑，然后将两者挤压接触，进而通过分子之间的吸力将所述透镜70与所述反射棱镜102接合。
请继续参阅图10，在本实施方式中，所述反射棱镜102的面上还可以具有发出部1025 和接收部1024，所述发出部1025用于向探测器发出光线；所述接收部1024用于从光源接收光线。本实施方式中，所述接收部1024可以从光源接收光线以维持闭合光路101的形成，具体的，例如光线由光源发出入射至所述接收部1024。所述接收部1024位于所述反射棱镜102的一个面上，其可以为所接收光线与其所在面的接触处。所述接收部1024的大小取决于所接收光线在其所在面上所形成的光斑大小，当然，所述接收部1024的大小不小于所接收光线在其所在面上所形成的光斑大小即可。
所述发出部1025可以向探测器发出光线至探测器，探测器通过接收该光线进行计算来得出待测样品的物化性质。所述发出部1025位于所述反射棱镜102的一个面上，其可以为所发出光线与其所在面的接触处。所述发出部1025的大小取决于所发出光线在其所在面上所形成的光斑大小，当然，所述发出部1025的大小不小于所发出光线在其所在面上所形成的光斑大小即可。
需要指出的是，所述接收部1024与所述发出部1025为不重合的两个部分，进而防止光源与探测器位置重叠。同时，在实际使用中考虑到光路是可逆的，所述接收部1024和所述发出部1025的位置可以互换，此时将光源与探测器的位置对调即可。当然，在本实施方式中，所述接收部1024和所述发出部1025可以位于所述反射棱镜102的不同面上。由于所述接收部1024与所述发出部1025位于不同面上，光源与探测器的位置可以灵活设置，进而便于制造和装配。
进一步的，所述接收部1024可以位于所述第二面1023上，所述发出部1025可以位于所述第一面1021上。可以看出，具有所述接收部1024的所述第二面1023可以从光源接收光线并将该光线反射出去，还可以接收来自所述第三面1022的光线并将其折射出去。具有所述接收部1024的所述第二面1023的折射位置可以与所述接收部1024位置重合，进而将该第二面1023的反射光线与折射光线的光路重合，便于光线形成所述闭合光路101。同样的，具有所述发出部1025的所述第一面1021可以接收来自其他光学元件的光线并将该光线部分向探测器发出，同时将该光线部分折射至所述第三面1022以形成闭合光路101。
请参阅图13，本申请一个实施方式还提供一种光学谐振腔100，其能接收和发出光线，并能将接收到的光线在内部传播，所述光学谐振腔包括：光学元件，所述光学元件包括至少一个如上任一实施方式所述的反射棱镜102；接收部1024，其用于从光源接收光线；发出部1025，其用于向探测器发出光线；所述接收部1024和所述发出部1025位 于所述光学元件的面上。
所述光学元件可以设置于用于容纳待测样品的测量区域103的边界上，进而保证位于两个所述光学元件之间的光线可以穿过所述待测样品并被所述待测样品吸收。所述入射光线可以采用P偏振光。进行测量工作时，光线由光源发出经所述接收部1024接收进入所述光学谐振腔100。光线在所述光学元件之间传播至所述反射棱镜102时，所述光学元件将光线反射至所述反射棱镜102的所述第一面1021，该第一面1021将光线通过折射并发送至当前反射棱镜102的所述第三面1022以完成入射工作，然后该第三面1022将光线反射给当前棱镜的所述第二面1023以完成反射工作，该第二面1023将光线折射后发送给下一光学元件的第一面1021以完成出射工作。每个光学元件顺次完成入射工作、反射工作、出射工作直至将光线形成稳定的闭合光路101。光线在所述光学元件之间传播时由所述发出部1025将光线向探测器发出，即发出出射光线。所述探测器接收所述出射光线，经过计算以得出所述待测样品的成分。
本实施方式中，所述光学元件能将光线形成闭合光路101，优选的闭合光路处于谐振状态的，进而增加光线在所述光学谐振腔100内的光程。处于谐振状态的闭合光路101中，光线能够在其中来回反射从而提供稳定的光能反馈。所述光学元件的数量为多个，其分布于所述测量区域103的边界，所述光学元件可以仅包含有所述反射棱镜102，组成棱镜型光学谐振腔100；也可以如图14及图17所示的包含有反射镜以及所述反射棱镜102，组成混合型光学谐振腔100；还可以包含有其他种类的反射棱镜102以及所述反射棱镜102。本申请并不以此为限，只需通过所述光学元件能保证光线形成闭合光路101即可。当然，在本申请中可以以所述光学元件仅包含所述反射棱镜102作为一种优选的方案。
本实施方式中，所述光学元件包含有至少一个所述反射棱镜102。所述反射棱镜102的数量可以不作限制，所述反射棱镜102为单个时，所述反射棱镜102可以与其他种类反射棱镜或反射镜相配合以将光线形成闭合光路101；所述反射棱镜102为多个时，所述反射棱镜102之间即可将光线形成闭合光路101，无须与其他种类反射棱镜102或反射镜配合。当然，在所述反射棱镜102为多个的情况下，依然可以与其他种类反射棱镜102或反射镜配合使用，本申请并不以此为限。本实施方式中，所述接收部1024可以从光源接收光线以维持闭合光路101的形成，具体的，例如光线由光源发出入射至所述接收部1024。所述接收部1024位于所述光学元件的一个面上，其可以为所接收光线与其所在面的接触处。所述接收部1024的大小取决于所接收光线在其所在面上所形成的光斑 大小，当然，所述接收部1024的大小不小于所接收光线在其所在面上所形成的光斑大小即可。
所述发出部1025可以向探测器发出光线，探测器通过接收该光线进行计算来得出待测样品的物化性质。所述发出部1025位于所述光学元件的一个面上，其可以为所发出光线与其所在面的接触处。所述发出部1025的大小取决于所发出光线在其所在面上所形成的光斑大小，当然，所述发出部1025的大小不小于所发出光线在其所在面上所形成的光斑大小即可。
所述接收部1024与所述发出部1025可以位于所述光学元件的同一面上可以位于不同面上，需要指出的是，所述接收部1024与所述发出部1025为不重合的两个部分，进而防止光源与探测器位置重叠。当然，在本实施方式中，可以以所述接收部1024和所述发出部1025可以位于所述光学元件的两个面上为优选的方案。在该优选的方案中，由于所述接收部1024与所述发出部1025位于不同面上，光源与探测器的位置可以灵活设置，进而便于制造和装配。
进一步的，所述接收部1024可以设在所有所述反射棱镜102中的一个所述第二面1023上，所述发出部1025可以设在所有所述反射棱镜102的一个所述第一面1021上。可以看出，具有所述接收部1024的所述第二面1023可以从光源接收光线并将该光线反射出去，还可以接收来自当前反射棱镜102的第三面1022的光线并将其折射出去。具有所述接收部1024的所述第二面1023的折射位置可以与所述接收部1024位置重合，进而将该第二面1023的反射光线与折射光线的光路重合，便于光线形成闭合光路101。同样的，具有所述发出部1025的所述第一面1021可以接收来自其他光学元件的光线并将该光线部分向探测器发出，同时将该光线部分折射至所述第三面1022以形成闭合光路101。
本实施方式中，所述光学元件可以为至少三个且每个均为所述反射棱镜102，进而可以使得具有所述接收部1024的所述第二面1023与具有所述发出部1025的所述第一面1021可以位于同一所述反射棱镜102上，也可以位于不同的所述反射棱镜102上，使得光源和探测器的位置可以灵活设置。在本实施方式中，光线通过所有所述反射棱镜102即可形成闭合光路101。所述反射棱镜102可以为非直线排布，再结合同一所述反射棱镜102中所述第三面1022与所述第二面1023为不同面，进而光线在所述反射棱镜102组成的闭合光路101中为单光路闭合传播，保证每个反射棱镜102的一个面只需承担入射工作或出射工作，其上仅存在一个入射光斑或出射光斑，使得该面的大小只需不小于所述入射光斑或出射光斑大小即可满足使用要求。
需要指出的是，考虑到光学元件集成度较高，所有所述反射棱镜102可以一体设计成型，但若其所行使的依然为多个所述反射棱镜102的作用时，依然为本申请所保护的方案。
本实施方式中，所述第一面1021用于接收来自其他光学元件的第二面1023的光线并将其折射至当前反射棱镜102的所述第三面1022。除去具有所述发出部1025的第一面1021外，在所有所述反射棱镜102中，每个所述第一面1021所接收的光线的入射角均可以为布儒斯特角。为保证所述第一面1021的透光率，所述第一面1021上可以镀设有高透膜，进而进一步降低光线的损耗，同时减少杂散光的出现。具有所述发出部1025的所述第一面1021其向探测器发出的光线的入射角需为非布儒斯特角，即θB+δ，δ≠0。所述出射光线由所述第一面1021发出后进入探测器，通过分析所述出射光线即可得出待测样品的物化性质。较佳的，所述第一面1021可以为布儒斯特面，即光线入射至该第一面1021的入射角为布儒斯特角或近布儒斯特角，在入射角为近布儒斯特角时，δ接近于0。
所述第二面1023用于接收来自当前反射棱镜102的第三面1022的光线并将其折射发出其他光学元件的第一面1021。除去具有所述接收部1024的第二面1023外，在所有所述反射棱镜102中，每个所述第二面1023所接收的光线经折射发出后所呈角度可以均为布儒斯特角。为保证所述第二面1023的透光率，所述第二面1023上可以镀设有高透膜，进而进一步降低光线的损耗，同时减少杂散光的出现。具有所述接收部1024的所述第二面1023上其从光源接收的光线的入射角为非布儒斯特角，即θB+δ，δ≠0。所述入射光线经所述第二面1023的反射光线与所述第二面1023所折射发出的光线光路重合。较佳的，所述第二面1023可以为布儒斯特面，即光线入射至该第二面1023的入射角为布儒斯特角或近布儒斯特角，在入射角为近布儒斯特角时，δ接近于0。
需要指出的是，具有所述接收部1024的所述第二面1023以及具有所述发出部1025的所述第一面1021可以为不同反射棱镜102的不同表面，也可以为同一反射棱镜102的不同表面，本申请并不以此为限。当然，为降低使用过程中调试的复杂程度，可以具有所述接收部1024的所述第二面1023以及具有所述发出部1025的所述第一面1021为同一反射棱镜102的不同表面作为优选的实施方式。
本实施方式中，所述第三面1022用于接收来自所述第一面1021的光线并将其全反射给所述第二面1023。为降低光线在反射过程中的损耗，所述第三面1022可以为全内 反射面。较佳的，所述第三面1022可以镀设有内反射膜，进而最大程度的降低光线在传播过程中的损耗。
以图13所示的光学谐振腔100为例，在所述反射棱镜102中，所述第三面1022远离所述检测区域，即远离待测样品；所述第二面1023、所述第一面1021以及未参与光学作用的表面与待测样品直接接触。通过此种设置，所述第三面1022不会受到待测样品以及待测样品中的杂质影响，如此，本实施方式所提供的光学谐振腔100的环境适应能力可以得到较大程度的提升。
请继续参阅图13，在本申请一种较佳的实施方式中，在所述光学谐振腔100中，所述光学元件可以包括有第一反射棱镜P、第二反射棱镜M以及第三反射棱镜N，通过所述第一反射棱镜P、所述第二反射棱镜M及所述第三反射棱镜N即可将光线形成闭合光路101。其中，在所述第一反射棱镜P上，所述第二面1023上具有所述接收部1024以从光源接收光线，所述第一面1021具有所述发出部1025以向探测器发出光线。
所述第一反射棱镜P的第二面1023与所述第二反射棱镜M的第一面1021通过第一光路L1连接，即光线由所述第一反射棱镜P的第二面1023发出后沿所述第一光路L1到达所述第二反射棱镜M的第一面1021。所述第三反射棱镜N的第二面1023与所述第一反射棱镜P的第二面1023通过第二光路L2连接，即光线由所述第三反射棱镜N的第二面1023发出后沿所述第二光路L2到达所述第一反射棱镜P的第二面1023。所述第二反射棱镜M的第二面1023与所述第三反射棱镜N的第一面1021通过第三光路L3连接，即光线由所述第二反射棱镜M的第二面1023发出后沿所述第三光路L3到达所述第三反射棱镜N的第一面1021。
在本实施方式中，所述第一光路L1与所述第二光路L2之间的夹角、所述第二光路L2与所述第三光路L3之间的夹角以及所述第三光路L3与所述第一光路L1之间的夹角均大于
Figure PCTCN2016107258-appb-000023
其中，θB为布儒斯特角。较佳的，每个所述反射棱镜中，所述第三面1022与所述第二面1023的夹角等于所述第三面1022与所述第一面1021的夹角，等于0.5倍的所述第一光路L1与所述第二光路的夹角L2加上θB。
所述第一反射棱镜P的第一面1021及第二面1023的最短边长取决于光斑大小，具体点，举例为边ab的长度至少应大于入射到边ab上的入射光斑的大小。特别需要说明的是，在所述第一反射棱镜P中边ad未承担光学作用，但考虑到边ab反射来杂散光等问题时，边ad所在面的角度可设置为布儒斯特角，以减少杂散光。
所述第一光路L1、所述第二光路L2、所述第三光路L3的长度可根据实际需要通过平移所述反射棱镜102调整，所述反射棱镜102的相对位置关系需满足上述公式即可。如对于在不强调光学谐振腔100大小的场合，所述第一光路L1、所述第二光路L2、所述第三光路L3的长度可设置为例如10厘米至100厘米；当对测量区域的大小有要求时，特别是要求尽可能的小时，所述第一光路L1、所述第二光路L2、所述第三光路L3的长度可设置为例如为毫米量级，甚至更小。
在一个具体的实施方式中，所述第一光路L1、所述第二光路L2、所述第三光路L3的延长线所形成的三角形可以为等边三角形，所述反射棱镜102材料的折射率n≈1.52，所述第一反射棱镜P、所述第二反射棱镜M、所述第三反射棱镜N的形状可以完全相同。考虑到实际设计和加工中会出现一定的偏差，∠cba＝∠dcb≈86.66°即，所述第三面1022与所述第二面1023的夹角近似为86.66度。
在一个可行的实施方式中，所述第一光路L1、所述第二光路L2、所述第三光路L3的延长线所形成的三角形可以为等腰三角形且所述第一光路L1、所述第二光路L2为所述等腰三角形的腰，所述反射棱镜102材料的折射率n≈1.52。虑到实际设计和加工中会出现一定的偏差，所述第一反射棱镜P中，∠cba＝∠dcb≈79.98°，即所述第三面1022与其所述第二面1023的夹角近似等于79.98度。所述第二反射棱镜M及所述第三反射棱镜N中，所述第三面1022与所述第二面1023的夹角近似等于90度。当然，所述第二反射棱镜M与所述第三反射棱镜N的形状可以相同。在本实施例中，所述第二反射棱镜M及所述第三反射棱镜N均可以为横截面为矩形的反射棱镜，非常便于设计和加工，有效增强了所述反射棱镜102的设计自由度。
在另一个可行的实施方式中，所述第一光路L1、所述第二光路L2、所述第三光路L3的延长线所形成的三角形可以为等腰三角形且所述第一光路L1、所述第二光路L2为所述等腰三角形的腰，所述反射棱镜102材料的折射率n≈1.52。虑到实际设计和加工中会出现一定的偏差，在所述第一反射棱镜P中，∠cba＝∠dcb≈90度，即所述第三面1022与其所述第二面1023的夹角近似等于90度。在所述第二反射棱镜M及所述第三反射棱镜N中，所述第三面1022与所述第二面1023的夹角近似等于84.98度。当然，所述第二反射棱镜M与所述第三反射棱镜N的形状可以相同。在本实施例中，所述第一反射棱镜P可以为横截面为矩形的反射棱镜，非常便于设计和加工，有效增强了所述反射棱镜102的设计自由度。
请参阅图15、图16、图17，在一个具体的实施方式中，所述光学元件可以包含有 四个所述反射棱镜，所有所述反射棱镜可以形成所述闭合光路。具体的，四个所述反射棱镜可以形成如图15所示的“口”字形闭合光路或者如图17所示的“Z”字形回路。此外，四个所述反射棱镜还可以形成如图16所示的“8”字形闭合光路。
需要指出的是，所述反射棱镜102的形状和数量并不限于上述几个举例性质的实施方式，所述三个反射棱镜同样可以形成如图14所示的“V”字形闭合光路，。所以所属领域技术人员在本申请技术精髓的启示下，还可能做出其它变更，但只要其实现的功能和效果与本申请相同或相似，均应涵盖于本申请保护范围内。
还需要指出的是，所述光学元件可以仅包含有一个所述反射棱镜102。此时，所述反射棱镜102整体可以为缺口圆环形状。所述反射棱镜102的缺口处可以为所述测量区域，所述缺口处的两个圆面为所述第一面1021和所述第二面1023；所述反射棱镜102的整个侧表面为所述第三面1022，进而保证在所述闭合光路中光线由所述第一面1021和所述第二面1023中的一面入射至所述反射棱镜102内并在所述第三面1022上发生多次反射后再由所述所述第一面1021和所述第二面1023中的一面发出。
本实施方式中，使用所述光学元件形成的光学谐振腔100的品质因素可用Q值来表示，定义为每周期内存储能量除以损耗的能量。Q值越高，光学谐振腔100存储能量的性能就越好，于是空腔光学谐振腔的灵敏度就越高。根据本申请以上描述，在所述光学元件中，所述光学元件能够旋转和/或平移，进而通过旋转和/或平移所述第一反射棱镜P调整反射损耗从而可对Q值和耦合进行控制。每一个玻璃表面的反射损耗取决于菲涅尔定律，损耗值约为10-4δθ2，δθ为偏离布儒斯特角的大小。同时，通过所述光学元件的平移可以调控相邻两个光学元件之间的距离，进而调节所述第一光路L1、第二光路L2以及第三光路L3的长度。
本实施方式中，为使所述光学谐振腔100所形成的闭合光路101保持稳定，控制光线在反射面所形成的衍射，可以设置所述光学元件中至少一个所述反射棱镜102的一个面应为曲面，即所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面为曲面。为了进一步校正光束斜入射时导致的像散，曲面的曲率和光束之间需满足消像散条件，参考应用光学的知识及借助光学设计软件可以解出所述曲面的曲率。
具体的，如图11所示，所述曲面可以为将所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面通过光学加工形成。所述光学加工可以为对所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面进行物理加工，例如打磨、抛光等。进一步的，如图12所示，所述曲面还可以为通过折射率系数相匹配的光学胶合 剂将透镜70与所述第一面1021、所述第二面1023以及所述第三面1022中的至少一个面胶合形成。所述光学胶合剂的折射率系数可以约等于所述曲面的折射率。所述透镜70与所述反射棱镜102的折射率可以相同，也可以不同，本申请并不以此为限。
此外，所述曲面也可以为将透镜70与所述第一面、所述第二面以及所述第三面中的至少一个面通过光学接触形成。所述光学接触为将透镜70的一面及所述第一面、所述第二面以及所述第三面中的至少一个面打磨光滑，然后将两者挤压接触，进而通过分子之间的吸力将所述透镜70与所述反射棱镜102接合。
为了更进一步的提高耦合效率，减少光束在光学谐振腔100的损耗，光束的模式与光学谐振腔100的模式需满足匹配条件，即耦合到光学光学谐振腔100的光线的腰斑半径及位置与光学谐振腔100的腰斑半径及位置完全重合。模式匹配的条件可用采用上述一般原理中记载的ABCD矩阵来计算。
请参阅图18、图19，在一个较佳的实施例中，所述光学谐振腔100可以包括匹配光学元件，所述匹配光学元件能将光线与光学谐振腔100的模式匹配。具体的，所述匹配光学元件位于测量区域103和/或用于将光源发出的光辐射(所述光辐射以倏逝波方式耦合入或耦合出光学谐振腔，或者以倏逝波方式与被测量样品接触)耦合至所述接收部1024，所述匹配光学件包括至少一个透镜80和/或至少一个反射镜90。所述匹配光学元件具有至少一个非平面，所述非平面包括：球面、柱面、椭球面、抛物面、自由曲面中的至少一种。
所述透镜80可以位于所述第一光路L1、所述第二光路L2以及所述第三光路L3中的一个光路或多个光路上。所述透镜80的数量可以为一个也可以为多个，且，所述匹配透镜80可以位于光路上的任意位置。
所述反射镜90将光辐射耦合至所述接收部1024。所述反射镜90能将光源发出的光线与光学谐振腔100的模式匹配。所述反射镜90能将光线以近布儒斯特角入射至所述接收部1024。所述反射镜90可以设于光源与所述接收部1024之间。
需要指出的是，上述几个实施方式仅为将光束的模式设置与光学谐振腔的模式满足匹配条件的举例性质的实施方式，所属领域技术人员在本申请技术精髓的启示下，还可能做出其它变更，但只要其实现的功能和效果与本申请相同或相似，均应涵盖于本申请保护范围内。
请参阅图20，本申请一个实施方式还提供一种光谱测量仪，包括：如上实施方式所 述的光学谐振腔100。
本发明的所用的测量方法为光学方法，包括但不限于：吸收光谱、拉曼光谱、散射谱、荧光、光声光谱、激发谱、傅立叶变换光谱、光频梳等光谱分析方法。
所述光谱测量仪可以包括腔衰荡光谱测量仪以及腔增强光谱测量仪，所述光学谐振腔100可以较好的应用于腔衰荡光谱测量仪以及腔增强光谱测量仪中，也可以应用于光声、拉曼、散射、激发、荧光等领域中。所述光谱测量仪可以包括光源控制模块200、光源模块201、外光路调整模块202、所述光学谐振腔100、光学谐振腔监测模块203、光学谐振腔控制模块208、样品预处理模块204、光电探测模块205、数据采集和处理模块206、数据和图像输出模块207。需要特别说明的是，图17中所示的各测量模块可根据实际测量需求进行适当的增加或减少，如待测样品不需要预处理时，样品预处理模块204可以省略。
所述光源控制模块200用于控制光源模块201的打开或关闭、频率调制、电流调谐、温度调谐等功能。
所述光源模块201根据探测技术和使用要求的不同可以有不同的形式，包括但不限于激光光源、宽带光源、不同频率激光光源的组合，激光光源和宽带光源的组合等。
所述外光路调整模块202用于改变光的偏振性质、光束的发散角、光场的能量分布等，并反馈信号给光源控制模块200，所述外光路调整模块202包括但不限于起偏装置、光学耦合、切光装置等。
所述光学谐振腔100为光学延迟系统，用于增加光的传播路径、增加光程，提高系统测量灵敏度，所述光学谐振腔100包括但不限于多次反射室、光学谐振腔等。所述光学谐振腔100包括有如上所述的光学元件。
所述光学谐振腔监测模块203用于监控反射腔101的工作状态、故障告警、在线实时标定光学谐振腔100的等效吸收光程，并提供监测信号给光学谐振腔控制模块208。
所述光学谐振腔控制模块208用于根据光学谐振腔监测模块203提供的监测信号在线实时校正光学谐振腔100内光学器件的相对位置关系，光学谐振腔控制模块208包括但不限于至少一块PZT或其他具有平移旋转功能的机械结构或装置或其组合来实现，从而改变光学谐振腔100光学器件的相对位置关系。
所述样品预处理模块204用于对待测样品进行预处理，所述样品预处理模块204包括但不限于加热待测样品、滤除样品中的水分、滤除样品中与测量无关的其他杂质、滤除粉尘等；
所述光电探测模块205用于接收和探测光学谐振腔100输出的光信号，并将光信号转化成电信号，进行信号的滤波、放大、模数转换等处理。
所述数据采集和处理模块206采集转化后的光电数字信号，并进行平均、浓度计算等光谱信号处理。
所述数据和图像输出模块207用于输出样品的光谱线、分子光谱吸收强度、浓度值等数据和图像信息。需要说明的是，所述数据和图像输出模块207的设置是为了显示元素浓度等信息，其形式和结构不受限制。
以上显示和描述了本发明的基本原理、主要特征及本发明的优点。本行业的技术人员应该了解，本发明不受上述实施例的限制，上述实施例和说明书中描述的只是说明本发明的原理，在不脱离本发明精神和范围的前提下，本发明还会有各种变化和改进，这些变化和改进都落入本发明要求保护的范围内。本发明要求保护范围由所附的权利要求书及其等效物界定。

Claims (12)

  1. 一种光学谐振腔用反射棱镜，所述光学谐振腔具有样品测量区域，其特征在于：所述反射棱镜包括用于接收穿过所述样品测量区域的光线的第一面、用于向所述样品测量区域发出光线的第二面、位于所述第一面与所述第二面之间的第三面；所述第三面用于将接收自所述第一面的光线全反射至所述第二面。
  2. 如权利要求1所述的反射棱镜，其特征在于：所述第一面及所述第二面为布儒斯特面，所述第三面为全内反射面。
  3. 如权利要求1所述的反射棱镜，其特征在于：所述反射棱镜的至少一个面为曲面。
  4. 一种光学谐振腔，其能接收和发出光线，并能将接收到的光线在内部传播，其特征在于，所述光学谐振腔包括：
    光学元件，所述光学元件包括至少一个如权利要求1至3任一所述的反射棱镜；
    所述光学谐振腔具有样品测量区域，所述样品测量区域能容置有待测样品。
  5. 如权利要求4所述的光学谐振腔，其特征在于：所述光学元件能形成闭合光路。
  6. 如权利要求4或5所述的光学谐振腔，其特征在于：所述光学元件至少为三个。
  7. 如权利要求6所述的光学谐振腔，其特征在于：每个所述光学元件均为所述反射棱镜。
  8. 如权利要求7所述的光学谐振腔，其特征在于：所有所述反射棱镜包括第一反射棱镜、第二反射棱镜以及第三反射棱镜；所述第一反射棱镜的第二面与所述第二反射棱镜的第一面通过第一光路连接，所述第三反射棱镜的第二面与所述第一反射棱镜的第一面通过第二光路连接，所述第二反射棱镜的第二面与所述第三反射棱镜的第一面通过第三光路连接；所述第一光路与所述第二光路之间的夹角、所述第二光路与所述第三光路之间的夹角以及所述第三光路与所述第一光路之间的夹角均大于
    Figure PCTCN2016107258-appb-100001
    其中，θB为布儒斯特角。
  9. 如权利要求8所述的光学谐振腔，其特征在于：每个所述反射棱镜中，所述第三面与所述第二面的夹角等于所述第三面与所述第一面的夹角，等于0.5倍的所述第一光路与所述第二光路的夹角加上θB。
  10. 如权利要求4所述的光学谐振腔，其特征在于，还包括：匹配光学元件，所述匹配光学元件能将光源的光学模式与光学谐振腔的光学模式相匹配。
  11. 如权利要求4所述的光学谐振腔，其特征在于：至少一个所述光学元件能够旋转和/或平移。
  12. 一种光谱测量仪，其特征在于，包括：如权利要求4至11任一所述的光学谐振腔。
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CN113302463B (zh) * 2018-12-19 2023-09-15 国家航空航天研究所 具有多个光学路径的仪器
CN115224579A (zh) * 2022-07-13 2022-10-21 广东大湾区空天信息研究院 一种光学频率梳产生装置

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