Quadruple optical path interferometer

Abstract

The invention discloses a quadruple optical path interferometer. A first single-face total reflection mirror and a second single-face total reflection mirror in the interferometer are obliquely arranged on a linear displacement platform and are perpendicular to each other; the beam splitter and the first target reflector are located on the two sides of the double-face total reflection mirror, and the first target reflector is perpendicular to the moving direction of the linear displacement platform. The first single-face total reflection mirror and the detector are located on the two sides of the beam splitter, and the first single-face total reflection mirror is parallel to the beam splitter. The second single-face reflector and the second target reflector are located on the two sides of the double-face holophote, the second target reflector is parallel to the moving direction of the linear displacement platform, and the second single-face holophote is parallel to the double-face holophote; and when the vertical distance from the central point of the double-sided holophote to the linear displacement platform is a first distance and the vertical distance from the central point of the double-sided holophote to the first target reflector is a second distance, the vertical distance from the central point of the double-sided holophote to the second target reflector is the sum of the second distance and two times of the first distance.

Description

Technical Field

[0001] The present application relates to the technical field of spectrometers, and in particular to a four-path interferometer. Background Art

[0002] Fourier Transform Infrared (FTIR) spectrometer is an optical instrument based on the interferometer. It uses the principle of optical interference to extract the intensity of incident light of different frequencies by interfering between two beams of light. It is often used to quickly identify the types of compounds and is widely used in many fields, including chemistry, life sciences, environmental testing, etc.

[0003] There are many types of interferometers for FTIR, the most common of which is the Michelson interferometer. Figure 1 As shown, the Michelson interferometer includes two plane total reflection mirrors M1 and M2, a beam splitter G1 and a compensation plate G2. Among them, M1 is a fixed mirror, M2 is a moving mirror, it is connected to a precision screw, and it can be moved forward and backward by rotating the drum wheel; the right surface of G1 is coated with a semi-transparent and semi-reflective film, which divides the incident light into two beams of equal intensity (reflected light and transmitted light); G2 and G1 are made of the same material, have the same thickness, and are installed in parallel, in order to make the two light beams participating in the interference pass through the glass plate the same number of times, and the two light beams do not introduce additional optical path difference due to the glass medium when they reach the observation area E; M1 and M2 are perpendicular, G1 and G2 are parallel, and G1 and G2 are at 45 degrees to M1 and M2 respectively. After the light source is projected onto G1 at an incident angle of 45 degrees, it is divided into two beams of light. One beam is reflected light, which is reflected back to G1 through M1, and the other beam is transmitted light, which passes through G2 and M2 and then returns to G1 along the original path. After the two beams of light return to G1, they interfere and reach the observation area E.

[0004] However, the traditional Michelson interferometer is a double optical path difference interferometer, that is, the optical path difference D of the interferometer changes with the moving distance d of the moving mirror M2 according to the formula D=2d. Therefore, how to provide a higher optical path difference interferometer to reduce the moving distance and thus reduce the volume of the overall structure is an urgent problem to be solved. Summary of the invention

[0005] The present application provides a four-fold optical path interferometer, which can provide an optical path difference interferometer with a higher multiple to reduce the moving distance, thereby reducing the volume of the overall structure.

[0006] The specific technical solutions are as follows:

[0007] In a first aspect, an embodiment of the present application provides a four-fold optical path interferometer, the interferometer comprising: a semi-reflective and semi-transmissive beam splitter, a first single-sided total reflection mirror, a second single-sided total reflection mirror, a first target reflection mirror, a second target reflection mirror, a double-sided total reflection mirror, a linear displacement platform, and a detector, wherein the first target reflection mirror and the second target reflection mirror are both reflection mirrors capable of reflecting all light;

[0008] The first single-sided total reflection mirror and the second single-sided total reflection mirror are respectively tiltedly arranged on the linear displacement platform, and the first single-sided total reflection mirror and the second single-sided total reflection mirror are perpendicular to each other;

[0009] The first single-sided total reflection mirror and the detector are respectively located on both sides of the beam splitter, and the center points of the first single-sided total reflection mirror, the detector and the beam splitter are on the same straight line, and the first single-sided reflection mirror is parallel to the beam splitter;

[0010] The second single-sided reflector and the second target reflector are respectively located on both sides of the double-sided total reflector, and the center points of the second single-sided reflector, the second target reflector and the double-sided total reflector are on the same straight line, the second target reflector is parallel to the moving direction of the linear displacement platform, and the second single-sided total reflector is parallel to the double-sided total reflector;

[0011] The beam splitter and the first target reflector are respectively located on both sides of the double-sided total reflector, and the center points of the beam splitter, the first target reflector and the double-sided total reflector are on the same straight line, and the first target reflector is perpendicular to the moving direction of the linear displacement platform;

[0012] When the vertical distance from the center point of the double-sided total reflection mirror to the linear displacement platform is the first distance, and the vertical distance from the center point of the double-sided total reflection mirror to the first target reflection mirror is the second distance, the vertical distance from the center point of the double-sided total reflection mirror to the second target reflection mirror is the sum of the second distance and twice the first distance;

[0013] Among them, after the light source is captured by the beam splitter perpendicular to the moving direction, it is divided into a reflected light beam path and a transmitted light beam path. On the reflected light beam path, the light beam passes through the first single-sided total reflection mirror, the second single-sided total reflection mirror, the double-sided total reflection mirror and the first target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. On the transmitted light beam path, the light beam passes through the double-sided total reflection mirror and the second target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. Finally, the light of the two light paths reaches the detector after interference.

[0014] In a possible implementation manner, the first target reflector is a corner reflector or a single-sided total reflector, and / or the second target reflector is a corner reflector or a single-sided total reflector.

[0015] In a possible implementation, the beam splitter, the first single-sided total reflection mirror, the second single-sided total reflection mirror, and the double-sided total reflection mirror have tilt angles of 45 degrees respectively.

[0016] In a possible implementation, the material of the beam splitter includes any one of calcium fluoride, potassium bromide, and zinc selenide; and / or,

[0017] The detector includes any one of a mercury cadmium telluride detector, an indium antimonide detector, a lead selenide detector, a DTGS detector, and an indium gallium arsenide detector.

[0018] In a second aspect, an embodiment of the present application provides a four-fold optical path interferometer, the interferometer comprising: a semi-reflective and semi-transmissive beam splitter, a first single-sided total reflection mirror, a second single-sided total reflection mirror, a first target reflection mirror, a second target reflection mirror, a linear displacement platform, and a detector, wherein the first target reflection mirror and the second target reflection mirror are both reflection mirrors capable of reflecting all light;

[0019] The first single-sided total reflection mirror and the second single-sided total reflection mirror are respectively tiltedly arranged on the linear displacement platform, and the first single-sided total reflection mirror and the second single-sided total reflection mirror are perpendicular to each other;

[0020] The first single-sided total reflection mirror and the detector are respectively located on both sides of the beam splitter, and the center points of the first single-sided total reflection mirror, the detector and the beam splitter are on the same straight line, and the first single-sided reflection mirror is parallel to the beam splitter;

[0021] The second target reflector is parallel to the moving direction of the linear displacement platform, the center lines of the beam splitter and the first target reflector are on the same straight line, and the first target reflector is located between the linear displacement platform and the second target reflector;

[0022] Wherein, after the light source is captured by the beam splitter perpendicular to the moving direction, it is divided into a reflected light beam path and a transmitted light beam path. On the reflected light beam path, the light passes through the first single-sided total reflection mirror, the second single-sided total reflection mirror, and the second target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. On the transmitted light beam path, the light passes through the first target reflection mirror and the second target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. Alternatively, on the transmitted light beam path, the light only passes through the second target reflection mirror, and is reflected back to the beam splitter along the original path. Finally, the light of the two light paths reaches the detector after interference.

[0023] The distance between the center point of the beam splitter and the center point of the first target reflector can make the optical path difference between the reflected light beam path and the transmitted light beam path four times the moving distance of the first single-sided total reflection mirror or the second single-sided total reflection mirror.

[0024] In a possible implementation, when the first target reflector is parallel to the second single-sided total reflector, the transmitted light beam passes through the first target reflector and the second target reflector in sequence on the light path of the transmitted light beam, and the distance between the center point of the beam splitter and the center point of the first target reflector is the sum of the third distance and twice the first distance and the third distance;

[0025] The first distance is the vertical distance from the center point of the double-sided total reflection mirror to the linear displacement platform;

[0026] The third distance is the distance between the center point of the first single-sided total reflection mirror and the center point of the second single-sided total reflection mirror.

[0027] In a possible implementation, when the first target reflector is perpendicular to the second target reflector, the transmitted light beam only passes through the second target reflector on its optical path, and the distance between the center point of the beam splitter and the center point of the first target reflector is 2*first distance+second distance+third distance;

[0028] The first distance is the vertical distance from the center point of the double-sided total reflection mirror to the linear displacement platform;

[0029] The second distance is a vertical distance from the center point of the first target reflector to the second target reflector;

[0030] The third distance is the distance between the center point of the first single-sided total reflection mirror and the center point of the second single-sided total reflection mirror.

[0031] In a possible implementation manner, the first target reflector is a corner reflector or a single-sided total reflector, and / or the second target reflector is a corner reflector or a single-sided total reflector.

[0032] In a possible implementation, the beam splitter, the first single-sided total reflection mirror, and the second single-sided total reflection mirror have tilt angles of 45 degrees respectively.

[0033] In a possible implementation, the material of the beam splitter includes any one of calcium fluoride, potassium bromide, and zinc selenide; and / or,

[0034] The detector includes any one of a mercury cadmium telluride detector, an indium antimonide detector, a lead selenide detector, a DTGS detector, and an indium gallium arsenide detector.

[0035] As can be seen from the above content, the embodiment of the present invention provides a four-fold optical path interferometer, which can make the optical path of the reflected light beam path include 4 times the moving distance by introducing two movable single-sided total reflection mirrors placed perpendicular to each other, and by setting the positions and distances of the first target reflection mirror, the second target reflection mirror, and the double-sided total reflection mirror (which may not be included), it can be achieved that the optical path difference between the reflected light beam path and the transmitted light beam path cancels each other at other distances, and only retains 4 times the moving distance, thereby realizing a four-fold optical path interferometer. Compared with the traditional Michelson interferometer, in order to achieve the same optical path difference, the moving distance of the interferometer of the embodiment of the present application is 1 / 4 of the optical path difference, which is 1 / 2 of the moving distance of the Michelson interferometer, which shows that the interferometer of the embodiment of the present application can achieve a spectral resolution twice that of the Michelson interferometer under the same moving distance of the moving mirror when applied to FTIR, and the reduction of the moving distance also helps to reduce the volume of the linear translation stage and the miniaturization of the overall structure.

[0036] The innovative features of the embodiments of the present application include:

[0037] 1. An embodiment of the present invention provides a four-fold optical path interferometer, which introduces two movable single-sided total reflection mirrors placed perpendicular to each other, so that the optical path of the reflected light beam path includes four times the moving distance, and by setting the positions and distances of the first target reflection mirror, the second target reflection mirror, and the double-sided total reflection mirror (which may not be included), the optical path difference between the reflected light beam path and the transmitted light beam path can be offset at other distances, and only four times the moving distance is retained, thereby realizing a four-fold optical path interferometer.

[0038] 2. The embodiment of the present application realizes a four-fold optical path interferometer by setting the following structure:

[0039] The first single-sided total reflection mirror and the second single-sided total reflection mirror are respectively tiltedly arranged on the linear displacement platform, and the first single-sided total reflection mirror and the second single-sided total reflection mirror are perpendicular to each other;

[0040] The first single-sided total reflection mirror and the detector are respectively located on both sides of the beam splitter, and the center points of the first single-sided total reflection mirror, the detector and the beam splitter are on the same straight line, and the first single-sided reflection mirror is parallel to the beam splitter;

[0041] The second single-sided reflector and the second target reflector are respectively located on both sides of the double-sided total reflector, and the center points of the second single-sided reflector, the second target reflector and the double-sided total reflector are on the same straight line, the second target reflector is parallel to the moving direction of the linear displacement platform, and the second single-sided total reflector is parallel to the double-sided total reflector;

[0042] The beam splitter and the first target reflector are respectively located on both sides of the double-sided total reflector, and the center points of the beam splitter, the first target reflector and the double-sided total reflector are on the same straight line, and the first target reflector is perpendicular to the moving direction of the linear displacement platform;

[0043] When the vertical distance from the center point of the double-sided total reflection mirror to the linear displacement platform is the first distance, and the vertical distance from the center point of the double-sided total reflection mirror to the first target reflection mirror is the second distance, the vertical distance from the center point of the double-sided total reflection mirror to the second target reflection mirror is the sum of the second distance and twice the first distance.

[0044] 3. The embodiment of the present application realizes another four-path interferometer by setting the following structure:

[0045] The first single-sided total reflection mirror and the second single-sided total reflection mirror are respectively tiltedly arranged on the linear displacement platform, and the first single-sided total reflection mirror and the second single-sided total reflection mirror are perpendicular to each other;

[0046] The first single-sided total reflection mirror and the detector are respectively located on both sides of the beam splitter, and the center points of the first single-sided total reflection mirror, the detector and the beam splitter are on the same straight line, and the first single-sided reflection mirror is parallel to the beam splitter;

[0047] The second target reflector is parallel to the moving direction of the linear displacement platform, the center lines of the beam splitter and the first target reflector are on the same straight line, and the first target reflector is located between the linear displacement platform and the second target reflector;

[0048] Wherein, after the light source is captured by the beam splitter perpendicular to the moving direction, it is divided into a reflected light beam path and a transmitted light beam path. On the reflected light beam path, it passes through the first single-sided total reflection mirror, the second single-sided total reflection mirror and the second target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. On the transmitted light beam path, it passes through the first target reflection mirror and the second target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. Alternatively, on the transmitted light beam path, it only passes through the second target reflection mirror and is reflected back to the beam splitter along the original path. Finally, the light of the two light paths reaches the detector after interference.

[0049] The distance between the center point of the beam splitter and the center point of the first target reflector can make the optical path difference between the reflected light beam path and the transmitted light beam path four times the moving distance of the first single-sided total reflector or the second single-sided total reflector.

[0050] Among them, when the first target reflector is parallel to the second single-sided total reflector, the transmitted light beam passes through the first target reflector and the second target reflector in sequence on the optical path, and the distance between the center point of the beam splitter and the center point of the first target reflector is the sum of the second distance and twice the first distance; the first distance is the vertical distance from the center point of the double-sided total reflector to the linear displacement platform; the second distance is the distance between the center point of the first single-sided total reflector and the center point of the second single-sided total reflector.

[0051] When the first target reflector is perpendicular to the second target reflector, the transmitted light beam only passes through the second target reflector, and the distance between the center point of the beam splitter and the center point of the first target reflector is 2*first distance+second distance+third distance; the first distance is the vertical distance from the center point of the double-sided total reflector to the linear displacement platform; the second distance is the distance between the center point of the first single-sided total reflector and the center point of the second single-sided total reflector; the third distance is the vertical distance from the center point of the first target reflector to the second target reflector. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art description are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work.

[0053] Figure 1 A schematic diagram of the structure of a Michelson interferometer provided by the prior art;

[0054] Figure 2 A schematic diagram of the structure of a four-path interferometer provided in an embodiment of the present application;

[0055] Figure 3 A schematic diagram of the structure of another quadruple optical path interferometer provided in an embodiment of the present application;

[0056] Figure 4 A schematic diagram of the structure of another quadruple optical path length interferometer provided in an embodiment of the present application;

[0057] Figure 5 A schematic diagram of the structure of another quadruple optical path interferometer provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0059] It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The terms "including" and "having" in the embodiments of the present application and the accompanying drawings and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0060] Since FTIR has a wide range of application scenarios, there are many types of spectrometers. Different spectrometer performance indicators are used for different application scenarios. The more important performance indicators include: spectral range, signal-to-noise ratio, wavenumber accuracy, and sampling time.

[0061] "Spectral range" refers to the frequency range that FTIR can measure. The spectral range of FTIR is usually divided into near infrared NIR, mid infrared MIR, and far infrared FIR. The spectral range is a very important indicator to measure the performance and application scenarios of FTIR. Since different molecules have different vibration and rotation energy levels, they can be used to identify different substances. Different instruments have different spectral ranges, which directly determines the application scenario of an FTIR. The spectral range of an FTIR is affected by many devices, and it is necessary to consider the emission power and wavelength of the infrared light source, as well as the selection of beam splitters and reflectors, etc.

[0062] "Signal-to-noise ratio" refers to the ratio of the signal intensity measured by FTIR to the noise intensity, which reflects the stability and reliability of the instrument. The higher the signal-to-noise ratio, the more accurate the spectral signal measured by FTIR, and the more reliable the spectral data.

[0063] "Spectral resolution" refers to the minimum wavelength or wavenumber difference that FTIR can distinguish, that is, the minimum distance between two adjacent peaks on the spectrum. Spectral resolution reflects the accuracy and sensitivity of the instrument. Higher resolution means clearer spectral details and higher signal-to-noise ratio. Spectral resolution is inversely proportional to the maximum optical path difference. For this reason, in order to pursue high spectral resolution, it is necessary to use FTIR with high optical path difference. This leads to two problems: large size of FTIR and decreased signal-to-noise ratio of FTIR. The large size problem greatly affects the scope of application of FTIR.

[0064] In order to reduce the optical path difference of FTIR, reduce the volume of FTIR, such as Figure 2 As shown, the embodiment of the present application provides a four-fold optical path interferometer, which includes: a semi-reflective and semi-transmissive beam splitter 11, a first single-sided total reflection mirror 12, a second single-sided total reflection mirror 13, a first target reflection mirror 14, a second target reflection mirror 15, a double-sided total reflection mirror 16, a linear displacement platform 17 and a detector 18, wherein the first target reflection mirror 14 and the second target reflection mirror 15 are both reflection mirrors capable of reflecting all light;

[0065] The first single-sided total reflection mirror 12 and the second single-sided total reflection mirror 13 are respectively tiltedly arranged on the linear displacement platform 17, and the first single-sided total reflection mirror 12 and the second single-sided total reflection mirror 13 are perpendicular to each other;

[0066] The beam splitter 11 and the first target reflector 14 are respectively located on both sides of the double-sided total reflector 16, and the center points of the beam splitter 11, the first target reflector 14 and the double-sided total reflector 16 are on the same straight line, and the first target reflector 14 is perpendicular to the moving direction of the linear displacement platform 17;

[0067] The first single-sided total reflection mirror 12 and the detector 18 are respectively located on both sides of the beam splitter 11, and the center points of the first single-sided total reflection mirror 12, the detector 18 and the beam splitter 11 are on the same straight line, and the first single-sided reflection mirror is parallel to the beam splitter 11;

[0068] The second single-sided reflector and the second target reflector 15 are respectively located on both sides of the double-sided total reflector 16, and the center points of the second single-sided reflector, the second target reflector 15 and the double-sided total reflector 16 are on the same straight line, the second target reflector 15 is parallel to the moving direction of the linear displacement platform 17, and the second single-sided total reflector 13 is parallel to the double-sided total reflector 16;

[0069] When the vertical distance from the center point of the double-sided total reflection mirror 16 to the linear displacement platform 17 is the first distance, and the vertical distance from the center point of the double-sided total reflection mirror 16 to the first target reflection mirror 14 is the second distance, the vertical distance from the center point of the double-sided total reflection mirror 16 to the second target reflection mirror 15 is the sum of the second distance and twice the first distance;

[0070] Among them, after the light source is captured by the beam splitter 11 perpendicular to the moving direction, it is divided into a reflected light beam path and a transmitted light beam path. On the reflected light beam path, it passes through the first single-sided total reflection mirror 12, the second single-sided total reflection mirror 13, the double-sided total reflection mirror 16 and the first target reflection mirror 14 in sequence, and is reflected back to the beam splitter 11 along the original path. On the transmitted light beam path, it passes through the double-sided total reflection mirror 16 and the second target reflection mirror 15 in sequence, and is reflected back to the beam splitter 11 along the original path. Finally, the light of the two light paths interferes and reaches the detector 18.

[0071] like Figure 3 As shown, if the first distance is represented by d1, the second distance is represented by d2, and the moving distance of the linear displacement platform 17 is represented by d, then the distance between the first single-sided total reflection mirror 12 and the beam splitter 11 is d+d1, and the distance between the second single-sided total reflection mirror 13 and the double-sided total reflection mirror 16 is d+d1. When the distance between the center points of the first single-sided total reflection mirror 12 and the second single-sided total reflection mirror 13 is the third distance d3, the distance between the middle point of the beam splitter 11 and the double-sided total reflection mirror 16 is also d3. The optical path of the reflected light beam is 4d1+2d2+2d3+4d, and the optical path of the transmitted light beam is 4d1+2d2+2d3. The optical path difference between the two is D=4d.

[0072] It should be supplemented that the first single-sided total reflection mirror 12 and the second single-sided total reflection mirror 13 move simultaneously.

[0073] The embodiment of the present invention provides a four-fold optical path interferometer, which can make the optical path of the reflected light beam path include four times the moving distance by introducing two movable single-sided total reflection mirrors placed perpendicular to each other, and by setting the positions and distances of the first target reflection mirror, the second target reflection mirror, and the double-sided total reflection mirror, it can be achieved that the optical path difference between the reflected light beam path and the transmitted light beam path cancels each other at other distances, and only retains four times the moving distance, thereby realizing a four-fold optical path interferometer. Compared with the traditional Michelson interferometer, in order to achieve the same optical path difference, the moving distance of the interferometer of the embodiment of the present application is 1 / 4 of the optical path difference, which is 1 / 2 of the moving distance of the Michelson interferometer. For example, the original required 1 cm moving distance now only requires 0.25-0.5 mm moving distance. This shows that the interferometer of the embodiment of the present application can achieve a spectral resolution twice that of the Michelson interferometer at the same moving distance of the moving mirror when applied to FTIR, and the reduction in moving distance also helps to reduce the volume of the linear translation stage and the miniaturization of the overall structure.

[0074] In one embodiment, the first target reflector 14 is a corner reflector or a single-sided total reflector, and / or the second target reflector 15 is a corner reflector or a single-sided total reflector.

[0075] In one implementation, the beam splitter 11 , the first single-sided total reflection mirror 12 , the second single-sided total reflection mirror 13 , and the double-sided total reflection mirror 16 have tilt angles of 45 degrees respectively.

[0076] When the inclination angle of the beam splitter 11, the first single-sided total reflection mirror 12, the second single-sided total reflection mirror 13, and the double-sided total reflection mirror 16 is 45 degrees, it can be ensured that the reflected light beam path and the transmitted light beam path only include two types of light rays, namely, light rays parallel to the moving direction and light rays perpendicular to the moving direction, thereby improving the accuracy of the four-fold optical path interferometer.

[0077] In one embodiment, the material of the beam splitter 11 includes any one of calcium fluoride CaF2, potassium bromide KBr, and zinc selenide ZnSe; and / or,

[0078] The detector 18 includes any one of a mercury cadmium telluride (MCT) detector 18 , an indium antimonide (InSb) detector 18 , a lead selenide (PbSe) detector 18 , a DTGS detector 18 , and an indium gallium arsenide (InGaAs) detector 18 .

[0079] Among them, the DTGS detector 18 is an infrared detector made by using the characteristic that the polarization of triglycine sulfate crystal (abbreviated as TGS) changes with temperature, and is called DTGS after deuteration treatment. The surfaces of the above-mentioned various reflectors can be coated or not. The wavelength range of the light source band is between 300nm and 20μm.

[0080] Figure 4 and Figure 5 A four-fold optical path interferometer provided in another embodiment of the present application includes: a semi-reflective and semi-transmissive beam splitter 21, a first single-sided total reflection mirror 22, a second single-sided total reflection mirror 23, a first target reflection mirror 24, a second target reflection mirror 25, a linear displacement platform 26 and a detector 27, wherein the first target reflection mirror 24 and the second target reflection mirror 25 are both reflection mirrors capable of reflecting all light;

[0081] The first single-sided total reflection mirror 22 and the second single-sided total reflection mirror 23 are respectively tiltedly arranged on the linear displacement platform 26, and the first single-sided total reflection mirror 22 and the second single-sided total reflection mirror 23 are perpendicular to each other;

[0082] The first single-sided total reflection mirror 22 and the detector 27 are respectively located on both sides of the beam splitter 21, and the center points of the first single-sided total reflection mirror 22, the detector 27 and the beam splitter 21 are on the same straight line, and the first single-sided reflection mirror is parallel to the beam splitter 21;

[0083] The second target reflector 25 is parallel to the moving direction of the linear displacement platform 26, the center lines of the beam splitter 21 and the first target reflector 24 are on the same straight line, and the first target reflector 24 is located between the linear displacement platform 26 and the second target reflector 25;

[0084] Among them, Figure 4 As shown, after the light source is captured by the beam splitter 21 perpendicular to the moving direction, it is divided into a reflected light beam path and a transmitted light beam path. On the reflected light beam path, it passes through the first single-sided total reflection mirror 22, the second single-sided total reflection mirror 23 and the second target reflection mirror 25 in sequence, and is reflected back to the beam splitter 21 along the original path. On the transmitted light beam path, it passes through the first target reflection mirror 24 and the second target reflection mirror 25 in sequence, and is reflected back to the beam splitter 21 along the original path, or, as Figure 5 As shown, the transmitted light beam only passes through the second target reflector 25 on the optical path, and is reflected back to the beam splitter 21 along the original path. Finally, the light of the two optical paths reaches the detector 27 after interference.

[0085] The distance between the center point of the beam splitter 21 and the center point of the first target reflector 24 can make the optical path difference between the reflected light beam path and the transmitted light beam path four times the moving distance of the first single-sided total reflection mirror 22 or the second single-sided total reflection mirror 23 .

[0086] The embodiment of the present invention provides a four-fold optical path interferometer, which can make the optical path of the reflected light beam include four times the moving distance by introducing two movable single-sided total reflection mirrors placed perpendicular to each other, and by setting the positions and distances of the first target reflection mirror and the second target reflection mirror, it can be achieved that the optical path difference between the reflected light beam path and the transmitted light beam path cancels each other at other distances, and only retains four times the moving distance, thereby realizing a four-fold optical path interferometer. Compared with the traditional Michelson interferometer, in order to achieve the same optical path difference, the moving distance of the interferometer of the embodiment of the present application is 1 / 4 of the optical path difference, which is 1 / 2 of the moving distance of the Michelson interferometer, which shows that the interferometer of the embodiment of the present application can achieve twice the spectral resolution of the Michelson interferometer under the same moving distance of the moving mirror when applied to FTIR, and the reduction of the moving distance also helps to reduce the volume of the linear translation stage and the miniaturization of the overall structure.

[0087] In one possible implementation, Figure 4 As shown, when the first target reflector 24 is parallel to the second single-sided total reflector 23, the transmitted light beam passes through the first target reflector 24 and the second target reflector 25 in sequence on the optical path, and the distance between the center point of the beam splitter 21 and the center point of the first target reflector 24 is the sum of the third distance and twice the first distance;

[0088] The first distance is the vertical distance from the center point of the double-sided total reflection mirror to the linear displacement platform 26;

[0089] The third distance is the distance between the center point of the first single-sided total reflection mirror 22 and the center point of the second single-sided total reflection mirror 23 .

[0090] like Figure 4As shown, if the first distance is represented by d1, the second distance is represented by d2, the third distance is represented by d3, and the moving distance of the linear displacement platform 26 is represented by d, then the distance between the first single-sided total reflection mirror 22 and the beam splitter 21 is d+d1, the distance between the second single-sided total reflection mirror 23 and the second target reflection mirror 25 is d+d1+d2, and the distance between the beam splitter 21 and the first target reflection mirror 24 is 2d1+d3. The optical path of the reflected light beam is 4d1+2d2+2d3+4d, and the optical path of the transmitted light beam is 4d1+2d2+2d3, and the optical path difference between the two is D=4d.

[0091] In one possible implementation, Figure 5 As shown, when the first target reflector 24 is perpendicular to the second target reflector 25, the transmitted light beam only passes through the second target reflector 25, and the distance between the center point of the beam splitter 21 and the center point of the first target reflector 24 is 2*the first distance+the second distance+the third distance;

[0092] The first distance is the vertical distance from the center point of the double-sided total reflection mirror to the linear displacement platform 26;

[0093] The second distance is the vertical distance from the center point of the first target reflector 24 to the second target reflector 25;

[0094] The third distance is the distance between the center point of the first single-sided total reflection mirror 22 and the center point of the second single-sided total reflection mirror 23 .

[0095] In a possible implementation, the first target reflector 24 is a corner reflector or a single-sided total reflector, and / or the second target reflector 25 is a corner reflector or a single-sided total reflector.

[0096] like Figure 5 As shown, if the first distance is represented by d1, the second distance is represented by d2, the third distance is represented by d3, and the moving distance of the linear displacement platform 26 is represented by d, then the distance between the first single-sided total reflection mirror 22 and the beam splitter 21 is d+d1, the distance between the second single-sided total reflection mirror 23 and the second target reflection mirror 25 is d+d1+d2, and the distance between the beam splitter 21 and the first target reflection mirror 24 is 2d1+d2+d3. The optical path of the reflected light beam is 4d1+2d2+2d3+4d, and the optical path of the transmitted light beam is 4d1+2d2+2d3, and the optical path difference between the two is D=4d.

[0097] In a possible implementation, the beam splitter 21 , the first single-sided total reflection mirror 22 , and the second single-sided total reflection mirror 23 are tilted at angles of 45 degrees respectively.

[0098] When the inclination angle of the beam splitter 21, the first single-sided total reflection mirror 22, and the second single-sided total reflection mirror 23 is 45 degrees, it can be ensured that the reflected light beam path and the transmitted light beam path only include two types of light rays, namely, light rays parallel to the moving direction and light rays perpendicular to the moving direction, thereby improving the accuracy of the four-fold optical path interferometer.

[0099] In a possible implementation, the material of the beam splitter 21 includes any one of calcium fluoride, potassium bromide, and zinc selenide; and / or,

[0100] The detector 27 includes any one of a mercury cadmium telluride detector 27 , an indium antimonide detector 27 , a lead selenide detector 27 , a DTGS detector 27 , and an indium gallium arsenide detector 27 .

[0101] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of one embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present application.

[0102] Those skilled in the art can understand that the modules in the device in the embodiment can be distributed in the device in the embodiment according to the description of the embodiment, or can be changed accordingly and located in one or more devices different from the embodiment. The modules in the above embodiment can be combined into one module, or can be further divided into multiple sub-modules.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A four-pass interferometer, characterized in that: The interferometer comprises: a semi-reflective and semi-transmissive beam splitter, a first single-sided total reflection mirror, a second single-sided total reflection mirror, a first target reflection mirror, a second target reflection mirror, a double-sided total reflection mirror, a linear displacement platform and a detector, wherein the first target reflection mirror and the second target reflection mirror are both reflection mirrors capable of reflecting all light; The first single-sided total reflection mirror and the second single-sided total reflection mirror are respectively tiltedly arranged on the linear displacement platform, and the first single-sided total reflection mirror and the second single-sided total reflection mirror are perpendicular to each other; The first single-sided total reflection mirror and the detector are respectively located on both sides of the beam splitter, and the center points of the first single-sided total reflection mirror, the detector and the beam splitter are on the same straight line, and the first single-sided reflection mirror is parallel to the beam splitter; The second single-sided reflector and the second target reflector are respectively located on both sides of the double-sided total reflector, and the center points of the second single-sided reflector, the second target reflector and the double-sided total reflector are on the same straight line, the second target reflector is parallel to the moving direction of the linear displacement platform, and the second single-sided total reflector is parallel to the double-sided total reflector; The beam splitter and the first target reflector are respectively located on both sides of the double-sided total reflector, and the center points of the beam splitter, the first target reflector and the double-sided total reflector are on the same straight line, and the first target reflector is perpendicular to the moving direction of the linear displacement platform; When the vertical distance from the center point of the double-sided total reflection mirror to the linear displacement platform is the first distance, and the vertical distance from the center point of the double-sided total reflection mirror to the first target reflection mirror is the second distance, the vertical distance from the center point of the double-sided total reflection mirror to the second target reflection mirror is the sum of the second distance and twice the first distance; Among them, after the light source is captured by the beam splitter perpendicular to the moving direction, it is divided into a reflected light beam path and a transmitted light beam path. On the reflected light beam path, the light beam passes through the first single-sided total reflection mirror, the second single-sided total reflection mirror, the double-sided total reflection mirror and the first target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. On the transmitted light beam path, the light beam passes through the double-sided total reflection mirror and the second target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. Finally, the light of the two light paths reaches the detector after interference.

2. The four-fold optical path length interferometer according to claim 1, characterized in that: The first target reflector is a corner reflector or a single-sided total reflector, and / or the second target reflector is a corner reflector or a single-sided total reflector.

3. The four-fold optical path length interferometer according to claim 1, characterized in that: The inclination angles of the beam splitter, the first single-sided total reflection mirror, the second single-sided total reflection mirror, and the double-sided total reflection mirror are 45 degrees respectively.

4. The four-fold optical path length interferometer according to any one of claims 1 to 3, characterized in that: The material of the beam splitter includes any one of calcium fluoride, potassium bromide and zinc selenide; and / or, The detector includes any one of a mercury cadmium telluride detector, an indium antimonide detector, a lead selenide detector, a DTGS detector, and an indium gallium arsenide detector.

5. A four-pass interferometer, characterized in that: The interferometer comprises: a semi-reflective and semi-transmissive beam splitter, a first single-sided total reflection mirror, a second single-sided total reflection mirror, a first target reflection mirror, a second target reflection mirror, a linear displacement platform and a detector, wherein the first target reflection mirror and the second target reflection mirror are both reflection mirrors capable of reflecting all light; The first single-sided total reflection mirror and the second single-sided total reflection mirror are respectively tiltedly arranged on the linear displacement platform, and the first single-sided total reflection mirror and the second single-sided total reflection mirror are perpendicular to each other; The first single-sided total reflection mirror and the detector are respectively located on both sides of the beam splitter, and the center points of the first single-sided total reflection mirror, the detector and the beam splitter are on the same straight line, and the first single-sided reflection mirror is parallel to the beam splitter; The second target reflector is parallel to the moving direction of the linear displacement platform, the center lines of the beam splitter and the first target reflector are on the same straight line, and the first target reflector is located between the linear displacement platform and the second target reflector; Wherein, after the light source is captured by the beam splitter perpendicular to the moving direction, it is divided into a reflected light beam path and a transmitted light beam path. On the reflected light beam path, it passes through the first single-sided total reflection mirror, the second single-sided total reflection mirror, and the second target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. On the transmitted light beam path, it passes through the first target reflection mirror and the second target reflection mirror in sequence, and is reflected back to the beam splitter along the original path. Alternatively, on the transmitted light beam path, it only passes through the second target reflection mirror and is reflected back to the beam splitter along the original path. Finally, the light of the two light paths reaches the detector after interference. The distance between the center point of the beam splitter and the center point of the first target reflector can make the optical path difference between the reflected light beam path and the transmitted light beam path four times the moving distance of the first single-sided total reflection mirror or the second single-sided total reflection mirror.

6. The four-fold optical path length interferometer according to claim 5, characterized in that: When the first target reflector is parallel to the second single-sided total reflector, the transmitted light beam passes through the first target reflector and the second target reflector in sequence on its optical path, and the distance between the center point of the beam splitter and the center point of the first target reflector is the sum of the second distance and twice the first distance and the second distance; The first distance is the vertical distance from the center point of the double-sided total reflection mirror to the linear displacement platform; The second distance is the distance between the center point of the first single-sided total reflection mirror and the center point of the second single-sided total reflection mirror.

7. The four-fold optical path length interferometer according to claim 5, characterized in that: When the first target reflector is perpendicular to the second target reflector, the transmitted light beam only passes through the second target reflector on its optical path, and the distance between the center point of the beam splitter and the center point of the first target reflector is 2*first distance+second distance+third distance; The first distance is the vertical distance from the center point of the double-sided total reflection mirror to the linear displacement platform; The second distance is the distance between the center point of the first single-sided total reflection mirror and the center point of the second single-sided total reflection mirror; The third distance is a vertical distance from a center point of the first target reflector to the second target reflector.

8. The four-fold optical path length interferometer according to claim 5, characterized in that: The first target reflector is a corner reflector or a single-sided total reflector, and / or the second target reflector is a corner reflector or a single-sided total reflector.

9. The four-fold optical path length interferometer according to claim 5, characterized in that: The inclination angles of the beam splitter, the first single-sided total reflection mirror, and the second single-sided total reflection mirror are 45 degrees respectively.

10. The four-fold optical path length interferometer according to any one of claims 5 to 9, characterized in that: The material of the beam splitter includes any one of calcium fluoride, potassium bromide and zinc selenide; and / or, The detector includes any one of a mercury cadmium telluride detector, an indium antimonide detector, a lead selenide detector, a DTGS detector, and an indium gallium arsenide detector.

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