Optical reflection cavity and flat optical path air chamber

Abstract

The embodiment of the utility model belongs to the field of gas detection, and provides an optical reflection cavity and a flat optical path gas chamber, the optical reflection cavity comprises an input end, an output end, a main concave reflector and two sub concave reflectors, the input end is located at the long axis center line of the main concave reflector, and the output end is located at the long axis center line of the sub concave reflector; the curvature center of the main concave reflector is located on the connecting line between the long axis centers of the two sub concave reflectors, the optical axis of the optical reflection cavity is perpendicular to the focal plane of the main concave reflector, and the output end of the optical reflection cavity is located on the long axis center line of the main concave reflector or the long axis center line of any sub concave reflector. A light beam is input into the light transmission plane from the input end, is reflected for multiple times between the main concave reflector and the two sub concave reflectors in the light transmission plane, and is output from the output end, and the light transmission plane is a plane where the long-axis center line of the main concave reflector and the long-axis center lines of the two sub concave reflectors are located. The optical reflection cavity and the flat optical path air chamber in the embodiment of the utility model can both adopt a flat form.

Description

TECHNICAL FIELD

[0001] The present application is suitable for the field of gas detection, and in particular relates to an optical reflection cavity and a flat optical path gas chamber. BACKGROUND

[0002] In some special gas detection scenarios, for example, in the field of environmental protection, the ultraviolet flue gas analysis system based on thermal humidification method, the Tunable Diode Laser Absorption Spectroscopy (TDLAS) detection system for monitoring escaped ammonia, the to-be-detected gas needs to be in a high-temperature state, and the optical path gas chamber needs to be heated to a high temperature of 150-350℃. Not only is it required that the optical path gas chamber has extremely high temperature stability, but also it is required that the optical path gas chamber has high temperature uniformity. The optical path gas chamber with non-uniform temperature will lead to inaccurate detection results, and even cause the high-temperature gas to condense at the low-temperature area of the optical element in the optical path gas chamber, resulting in failure of the optical system. How to improve the temperature stability and temperature uniformity of the optical path gas chamber is a problem to be solved at present. SUMMARY

[0003] Therefore, the present application provides an optical reflection cavity and a flat optical path gas chamber, which can improve the temperature stability and temperature uniformity of the optical path gas chamber.

[0004] The first aspect of the present application provides an optical reflection cavity, comprising:

[0005] an input end for inputting a light beam;

[0006] an output end for outputting the light beam, the input end and the output end being arranged separately;

[0007] a main plane mirror, the input end and the output end being located at a long axis center line of the main plane mirror;

[0008] a concave mirror having a focal plane, a distance from the focal plane to the concave mirror being a focal length f of the concave mirror, the long axis center line intersecting an optical axis of an optical system composed of the main plane mirror and the concave mirror; and

[0009] an inclined sub-mirror, which is a plane mirror with an area smaller than that of the main plane mirror, an inclined angle between a normal line of the inclined sub-mirror and a normal line of the main plane mirror being θ1 and located in a light transmission plane, the inclined angle θ1 being non-zero, and the light transmission plane being a plane where the long axis center line and the optical axis are located;

[0010] wherein the main plane mirror and the inclined sub-mirror are coplanar and located at the focal plane of the concave mirror;

[0011] The light beam is input from the input end into the light transmission plane, and is output from the output end after multiple reflections among the concave mirror, the main plane mirror and the tilt sub-mirror in the light transmission plane.

[0012] In one embodiment, the optical reflection cavity further comprises:

[0013] A driving mechanism is configured to drive the tilt sub-mirror to periodically move back and forth along a Z-axis direction during each data acquisition process of a detection process of gas absorption data, wherein the Z-axis direction is parallel to the optical axis.

[0014] The detection process is that, in the case that the optical reflection cavity is filled with a gas to be detected, a light beam is input from the input end into the light transmission plane, and is output from the output end after multiple reflections among the concave mirror, the main plane mirror and the tilt sub-mirror in the light transmission plane, and the input wavelength of the light beam varies in a preset wavelength range during the entire detection process, and the input wavelength of the light beam is constant or varies in a preset wavelength modulation range during each data acquisition process.

[0015] In one embodiment, the Z-axis direction includes parallel and opposite Z-axis positive direction and Z-axis negative direction.

[0016] The position change value of the tilt sub-mirror when moving along the Z-axis positive direction is positive.

[0017] The position change value of the tilt sub-mirror when moving along the Z-axis negative direction is negative.

[0018] When the tilt sub-mirror moves back and forth along the Z-axis direction,

[0019] Wherein, δ represents the position change value of the tilt sub-mirror in the Z-axis direction, and λ represents the input wavelength of the light beam.

[0020] The second aspect of the embodiments of the present application provides an optical reflection cavity, comprising:

[0021] An input end for inputting a light beam;

[0022] An output end for outputting a light beam;

[0023] A main concave mirror, wherein the input end is located at the center line of the long axis of the main concave mirror; and

[0024] Two sub-concave mirrors, wherein the center of curvature of the main concave mirror is located on the line between the center lines of the long axes of the two sub-concave mirrors, and the optical axis of the optical reflection cavity is perpendicular to the focal plane of the main concave mirror.

[0025] wherein the output end is located on a long axis center line of the main concave mirror or a long axis center line of any of the two sub-concave mirrors;

[0026] The light beam is input from the input end into a light transmission plane, and is output from the output end after multiple reflections between the main concave mirror, the main plane mirror and the tilted sub-mirror in the light transmission plane, the light transmission plane being a plane in which the long axis center line of the main concave mirror and the long axis center lines of the two sub-concave mirrors are located.

[0027] In one embodiment, the optical reflection cavity further comprises:

[0028] A driving mechanism is configured to drive the M sub-concave mirrors to periodically move back and forth along a Z-axis direction during each data acquisition process of a detection process of gas absorption data, the Z-axis direction being parallel to an optical axis of an optical system composed of the main concave mirror and the two sub-concave mirrors.

[0029] wherein M≥1, and the detection process is that, in a case where the optical reflection cavity is filled with a gas to be detected, a light beam is input from the input end into the light transmission plane, and is output from the output end after multiple reflections between the main concave mirror and the two sub-concave mirrors in the light transmission plane, the input wavelength of the light beam varying in a preset wavelength range during the entire detection process, and the input wavelength of the light beam being constant or varying in a preset wavelength modulation range during each data acquisition process.

[0030] In one embodiment, the Z-axis direction includes parallel and opposite Z-axis positive direction and Z-axis negative direction.

[0031] The position change value of the sub-concave mirror when moving along the Z-axis positive direction is positive.

[0032] The position change value of the sub-concave mirror when moving along the Z-axis negative direction is negative.

[0033] When the M sub-concave mirrors move back and forth periodically along the Z-axis direction,

[0034] wherein δ represents the sum of the position change values of the M sub-concave mirrors in the Z-axis direction, and λ represents the input wavelength of the light beam.

[0035] A third aspect of the embodiments of the present application provides a flat optical path gas cell, which comprises an optical reflection cavity provided by any one of the aspects of the embodiments of the present application, the width, height and length of the flat optical path gas cell being parallel to the long axis of the main plane mirror, the short axis of the main plane mirror and the optical axis, respectively.

[0036] Alternatively, the optical reflection cavity provided by the two aspects of the embodiments of the present application comprises a flat optical path gas chamber, and the width, height and length of the flat optical path gas chamber are parallel to the long axis of the main concave mirror, the short axis of the main concave mirror and the optical axis of the optical reflection cavity respectively.

[0037] In one embodiment, the flat optical path gas chamber further comprises a sealed gas chamber body, and any side wall of the sealed gas chamber body is provided with an air inlet and an air outlet, and the air inlet and the air outlet do not pass through the transmission light path of the light beam.

[0038] The optical reflection cavity is located in the sealed gas chamber body, or the sealed gas chamber body is located in the optical reflection cavity, and the sealed gas chamber body is provided with a light transmission window parallel to the two side walls in the direction of the optical axis of the optical reflection cavity, and the light transmission window is used for input and output of the light beam.

[0039] In one embodiment, the flat optical path gas chamber further comprises a temperature adjusting component, which is wrapped around any outer side wall of the sealed gas chamber body and does not pass through the transmission light path of the light beam, and is used for adjusting the temperature of the to-be-detected gas in the optical reflection cavity.

[0040] In one embodiment, the ratio of the height to the width of the flat optical path gas chamber is less than or equal to 1 / 4.

[0041] In one embodiment, the air inlet and the air outlet are arranged on any side wall of the sealed gas chamber body perpendicular to the direction of the optical axis.

[0042] In one embodiment, the temperature adjusting component comprises at least one of a heating film and a cooling film.

[0043] The optical reflection cavity provided by the first aspect of the embodiments of the present application is arranged such that the input end and the output end are located on the long axis center line of the main plane mirror, the long axis center line intersects the optical axis of the optical system composed of the main plane mirror and the concave mirror, and the normal line of the inclined sub-mirror is located on the light transmission plane formed by the long axis center line and the optical axis, so that the light beam can be input from the input end to the light transmission plane, and after multiple reflections among the concave mirror, the main plane mirror and the inclined sub-mirror in the light transmission plane, the light beam is output from the output end. Since the reflection path of the light beam in the optical reflection cavity is in the light transmission plane, the optical reflection cavity can adopt a flat shape.

[0044] The second aspect of the embodiment of the present application provides the optical reflection cavity. The input end is located at the center line of the long axis of the main concave mirror, the center of curvature of the main concave mirror is located at the line connecting the centers of the long axes of the two sub-concave mirrors, and the output end is located at the center line of the long axis of the main concave mirror or the center line of the long axis of any sub-concave mirror. The light beam can be input from the input end to the light transmission plane in which the center line of the long axis of the main concave mirror and the center line of the long axis of the two sub-concave mirrors are located, and output from the output end after multiple reflections between the main concave mirror and the two sub-concave mirrors in the light transmission plane. Since the reflection path of the light beam in the optical reflection cavity is in the light transmission plane, the optical reflection cavity can adopt a flat shape.

[0045] The third aspect of the embodiment of the present application provides the flat optical path gas chamber. The optical reflection cavity provided by the first aspect or the second aspect of the embodiment of the present application is adopted. Since the reflection path of the light beam in the optical reflection cavity is in the light transmission plane, the optical reflection cavity can adopt a flat shape, so that the width, height and length of the flat optical path gas chamber can be parallel to the long axis of the main plane mirror, the short axis of the main plane mirror and the optical axis of the optical reflection cavity provided by the first aspect, or parallel to the long axis of the main concave mirror, the short axis of the main plane mirror and the optical axis of the optical reflection cavity provided by the second aspect, so that the flat optical path gas chamber can also adopt a flat shape. The sealed gas chamber body is located in the optical reflection cavity, light transmission windows are arranged on the two side walls of the sealed gas chamber body in the direction parallel to the optical axis of the optical reflection cavity, for input and output of the light beam, and gas inlets and outlets are arranged on any side wall of the sealed gas chamber body, so that the gas inlets and outlets do not pass through the transmission path of the light beam, which can avoid the erosion or pollution of the reflection elements of the optical reflection cavity by the to-be-detected gas. The temperature adjusting component is wrapped on any outer side wall of the sealed gas chamber body and does not pass through the transmission path of the light beam, so as to adjust the temperature of the to-be-detected gas in the case that the to-be-detected gas is filled in the optical reflection cavity. Since the flat optical path gas chamber can adopt a flat shape, the heat exchange efficiency between the sealed gas chamber body and the to-be-detected gas can be improved, so that the temperature adjusting efficiency of the flat optical path gas chamber can be improved, and the temperature stability and uniformity of the optical elements and the to-be-detected gas in the flat optical path gas chamber are also improved. In the case that the sealed gas chamber body is located in the optical reflection cavity, the reflection elements are far away from the sealed gas chamber body, so that the reflection elements can be prevented from being affected by the temperature change of the sealed gas chamber body and eroded or polluted by the to-be-detected gas. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical application in the embodiments of the present application, the drawings needed in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0047] In order to more clearly illustrate the technical application in the embodiments of the present application, the drawings needed in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0048] Figure 1 is a structural schematic diagram of an optical reflection cavity provided by an embodiment of the present application;

[0049] Figure 2 is a light spot trajectory schematic diagram on a main plane mirror provided by an embodiment of the present application;

[0050] Figure 3 is a tilt direction schematic diagram of a tilt sub-mirror provided by an embodiment of the present application;

[0051] Figure 4 is a structural schematic diagram of an optical reflection cavity provided by an embodiment of the present application;

[0052] Figure 5 is a structural schematic diagram of an optical reflection cavity provided by an embodiment of the present application;

[0053] Figure 6 is a structural schematic diagram of an optical reflection cavity provided by an embodiment of the present application;

[0054] Figure 7 is a structural schematic diagram of an optical reflection cavity provided by an embodiment of the present application;

[0055] Figure 8 is a structural schematic diagram of an optical reflection cavity provided by an embodiment of the present application;

[0056] Figure 9 is a structural schematic diagram of an optical reflection cavity provided by an embodiment of the present application;

[0057] Figure 10 is a light spot trajectory schematic diagram on a main concave mirror provided by an embodiment of the present application;

[0058] Figure 11 is a structural schematic diagram of an optical reflection cavity provided by an embodiment of the present application;

[0059] Figure 12is a structure of a flat optical path gas chamber and a light spot trajectory schematic diagram provided by an embodiment of the present application.

[0060] Figure 13 is a structure schematic diagram of a flat optical path gas chamber provided by an embodiment of the present application. DETAILED DESCRIPTION

[0061] In the following description, for the purpose of explanation and not limitation, specific details are set forth, such as particular system configurations, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

[0062] In order to illustrate the technical application described in the present application, the following will be described by specific embodiments.

[0063] In order to make the technical field personnel better understand the present application, the technical application in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0064] The term "include" and any variation thereof in the specification and claims of the present application and the above-mentioned drawings is intended to cover non-exclusive inclusion. In addition, the terms "first" and "second" and the like are used to distinguish different objects, rather than to describe a specific order.

[0065] Embodiment one

[0066] As shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 or Figure 5 The present application provides an optical reflection cavity 100, comprising:

[0067] The input end 101 is used for inputting a light beam;

[0068] The output end 102 is used for outputting a light beam, and the input end 101 and the output end 102 are arranged separately;

[0069] The main plane mirror 104 is arranged on the long axis center line 104a of the main plane mirror 104;

[0070] The concave mirror 103 has a focal plane 106, the distance 107 between the focal plane 106 and the concave mirror 103 is the focal length f of the concave mirror 103, the focal plane 106 has an origin 109, the origin 109 is the intersection of the optical axis 108 of the optical system composed of the main plane mirror 104 and the concave mirror 103 on the focal plane 106, and the long axis center line 104a intersects the optical axis 108; and

[0071] The inclined sub-mirror 105 is a plane mirror with an area smaller than that of the main plane mirror 104, the inclination angle between the normal 114 of the inclined sub-mirror 105 and the normal 115 of the main plane mirror 104 is θ1 and is located in the light transmission plane xz, the inclination angle θ1 is not zero, and the light transmission plane xz is the plane in which the long axis center line 104a, the optical axis 108 and the long axis center line 103a of the concave mirror 103 are located;

[0072] The main plane mirror 104 and the inclined sub-mirror 105 are coplanar and located in the focal plane 106 of the concave mirror 103.

[0073] The light beam is input from the input end 101 into the light transmission plane xz, and after multiple reflections between the concave mirror 103, the main plane mirror 104 and the inclined sub-mirror 105 in the light transmission plane xz, the light beam is output from the output end 102.

[0074] In application, the long axis center line 104a is the center line on the main plane mirror 104 parallel to the long axis of the main plane mirror 104. Taking a three-dimensional Cartesian coordinate system XYZ as an example, the long axis of the main plane mirror 104 and the long axis center line 104a are parallel to the X-axis direction of the three-dimensional Cartesian coordinate system XYZ, the optical axis 108 is parallel to the Z-axis direction of the three-dimensional Cartesian coordinate system XYZ, and the light transmission plane xz is in the XZ plane of the three-dimensional Cartesian coordinate system XYZ.

[0075] In application, from the optical characteristics, since the confocal system is adopted, on the focal plane 106, the radius and the divergence half-angle of the light beam will change between two groups of values, which is irrelevant to the number of reflections of the concave mirror 103, and only related to the parity of the number of reflections of the concave mirror 103. Assuming that the radius of the light beam input by the input end 101 is A0, the divergence half-angle is β0, the radius of the light beam after one reflection of the concave mirror 103 to the focal plane 106 is A1, and the divergence half-angle is β1, then the following relationships exist:

[0076] A1 = β0·f (1)

[0077] β1 = A0 / f (2)

[0078] The radius of the light beam after two reflections by the concave mirror 103 to the focal plane 106 is A2, and the divergence half-angle is β2, which can be obtained by applying equations (1) and (2) twice:

[0079] A2 = β1·f = (A0 / f)·f = A0 (3)

[0080] β2 = A1 / f = (β0·f) / f = β0 (4)

[0081] As can be seen from equations (3) and (4), the input light beam after two reflections by the concave mirror 103 to the focal plane 106 restores the characteristics (A0, β0) of the input light beam. It can be easily seen that after an even number of reflections by the concave mirror 103, the characteristics of the light beam will be the same as those of the input light beam; for an odd number of reflections by the concave mirror 103, the characteristics of the light beam will take the radius and divergence half-angle (A1, β1) obtained from equations (1) and (2).

[0082] For the transformation of the position and angle (relative to the optical axis 108) of the main beam of the input light beam, without introducing the tilted sub-mirror 105, it can be proved that after four reflections by the concave mirror 103 to the focal plane 106, the position of the main beam of the light beam coincides with that of the input light beam, and the angle of the main beam of the light beam is mirror-symmetric about the optical axis 108 with the angle of the main beam of the input light beam; since the position of the main beam of the light beam coincides with that of the input light beam, the light beam is no longer reflected by the main plane mirror 104, but is output through the input end 101, so without introducing the tilted sub-mirror 105, the light beam is reflected by the concave mirror 103 at most four times, and the total optical path is greatly limited.

[0083] The embodiment of the present application introduces a tilted sub-mirror 105 on the basis of the confocal optical system composed of the concave mirror 103 and the main plane mirror 104, which is located a certain distance away from the origin 109 and at the position where the input light beam reaches the focal plane 106 after being reflected by the concave mirror 103 for the first or third time. The tilted sub-mirror 105 changes the reflection angle of the light beam, so that after the light beam is reflected by the concave mirror 103, the position of the light beam on the focal plane 106 after subsequent even-numbered reflections is changed, while the position of the light beam on the focal plane 106 after odd-numbered reflections remains unchanged, so that the positions of all light beams no longer conflict with the input end 101, and multiple reflections of the light beam are achieved.

[0084] It can be proved that, as Figure 2As shown, after the introduction of the tilted sub-mirror 105, the positions of the light beams reflected by the concave mirrors 1+4n (n=0, 1, 2, 3, ···) are at the same position, denoted as P1 (i.e. 110); the positions of the light beams reflected by the concave mirrors 3+4n (n=0, 1, 2, 3, ···) are at the same position, denoted as P3 (i.e. 111); the positions of the light beams reflected by the concave mirrors 4+4n (n=0, 1, 2, 3, ···) are P4, P8, P 12 , ···, which are on a straight line with the position P0 of the input light beam, denoted as L4 (i.e. 112); the positions of the light beams reflected by the concave mirrors 2+4n (n=0, 1, 2, 3, ···) are P2, P6, P 10 , ···, which are on a straight line with L4 (112), denoted as L2 (i.e. 113).

[0085] For the convenience of illustration, as shown in Figure 2 and Figure 3 , the tilted sub-mirror 105 is selected at the position P3 (111) of the light beam reflected by the concave mirror 103 for the third time, and the normal line 114 of the tilted sub-mirror 105 forms an angle θ1 with the normal line 115 of the main plane mirror 104. A vector formed along the two normal lines and intersecting the focal plane 106 to form a ridge line direction is called a displacement vector ΔP (i.e. 116), and the length of the displacement vector ΔP is defined by the following formula:

[0086] ΔP = tan(2θ1)·f (5)

[0087] It can be proved that the interval between the adjacent light beam positions P2, P6, P 10 , ··· on L2 and the interval between the adjacent light beam positions P0, P4, P8, P 12 , ··· on L4 are ΔP (116) given by formula (5), and L2 (113) and L4 (112) are parallel to ΔP (116). It can be seen that ΔP contains the size and direction of the angle θ1 of the tilted sub-mirror 105.

[0088] According to the properties of the confocal optical system, P1 (110) and P3 (111) are symmetric about the origin 109 of the focal plane. In order to prevent the tilted sub-mirror 105 from interfering with the light beams on P1, the distance of the tilted sub-mirror 105 from the origin 109 of the focal plane is greater than the radius A1 of the light beams on P1 (110) or P3 (111), and A1 = β0·f according to formula (1) above. At the same time, in order to ensure that the tilted sub-mirror 105 can reflect all the light beam energy reaching it, the clear aperture diameter of the tilted sub-mirror 105 is greater than the diameter 2·A1 of the light beams on P1 or P3, i.e. 2β0·f.

[0089] In order to make the light beams on L2(113) and L4(112) in the light transmission plane xz, the selection of the tilt angle θ1 direction makes the direction of the displacement vector ΔP(116) in the direction of the line between the input end 101 and P3(111), after the light beam reaches the focal plane 106 after being reflected by the even number of concave mirrors 103, the distance from the center of the input light beam to the boundary of the tilt sub-mirror 105 is equal to the radius A0 of the input light beam, so that the light transmission band with the light beam diameter as the width on L2(113) and L4(112) overlaps with the tilt sub-mirror 105.

[0090] The output end 102 can be taken on L2(113) or L4(112), preferably on L4(112), that is, the output end 102 is located at the position where the input light beam reaches the focal plane 106 after being reflected by the concave mirror 103 for 4 times of an integer, so that the input end 101 and the output end 102 are on both sides of L4(112); this configuration of the output end 102 makes the position and angle of the output light beam insensitive to the angle deviation of the concave mirror 103 relative to the main plane mirror 104, and the optical system has high stability.

[0091] In one embodiment, the input end 101 is a first fiber collimator with a first tail fiber, and the light beam is input through the first fiber collimator;

[0092] Alternatively, the input end 101 is a first fiber collimator array with a first tail fiber array, and the light beam is input through the first fiber collimator array;

[0093] Alternatively, the input end 101 is a light transmission hole or an opening angle on the main plane mirror 104, and the light beam enters the input end 101 from the free space;

[0094] Alternatively, the input end 101 is connected to a light emitting device through an optical fiber, and the input end 101 inputs the light beam emitted by the light emitting device;

[0095] The output end 102 is a second fiber collimator with a second tail fiber, and the light beam is output through the second fiber collimator;

[0096] Alternatively, the output end 102 is a second fiber collimator array with a second tail fiber array, and the light beam is output through the second fiber collimator array;

[0097] Alternatively, the output end 102 is a light transmission hole or an opening angle on the main plane mirror 104, and the light beam is output from the output end 102 to the free space;

[0098] Alternatively, the output end 102 is connected to a light sensing device through an optical fiber, and the light beam is received by the light sensing device;

[0099] Alternatively, the output end 102 is connected to an array of light sensing devices through an optical fiber, and the light beam is received by the array of light sensing devices.

[0100] In applications, the form of the aperture and the opening angle are suitable for incoherent beams with a large divergence angle. For coherent beams with a small divergence angle, such as lasers, a fiber collimator with a pigtail is selected as the input end, and a fiber collimator with a pigtail is selected as the output end accordingly. Alternatively, a photosensitive device can be selected to directly receive the beam.

[0101] In one embodiment, the distance between the tilted sub-mirror 105 and the intersection of the optical axis 108 and the focal plane 106 is greater than the product β0·f between the divergence half-angle β0 of the input beam and the focal length f of the concave mirror 103.

[0102] In one embodiment, the tilting sub-reflector 105 is located at the position where the light beam reaches the focal plane 106 after the first or third reflection by the concave reflector 103, and the light transmission diameter of the tilting sub-reflector 105 is greater than 2β0·f.

[0103] In one embodiment, the tilt angle θ1 of the tilt sub-reflector 105 is selected such that when the light beam reaches the focal plane 106 after an even number of reflections by the concave reflector 103, the distance from the center of the light beam to the boundary of the tilt sub-reflector 105 is greater than the input radius A0 of the light beam.

[0104] The optical reflection cavity 100 provided in this embodiment can realize multiple reflections of the light beam, has a long optical path and a high optical path-to-volume ratio, and is compact in size. By positioning the input end 101 and the output end 102 at the center line 104a of the major axis of the main plane mirror 104, the center line 104a intersects the optical axis 108 of the optical system composed of the main plane mirror 104 and the concave mirror 103, and the normal 114 of the tilted sub-mirror 105 is located in the light transmission plane xz where the center line 104a and the optical axis 108 are located, the light beam can be input from the input end 101 into the light transmission plane xz. After multiple reflections between the concave mirror 103, the main plane mirror 104 and the tilted sub-mirror 105 in the light transmission plane xz, the light beam is output from the output end 102. Since the reflected light path of the light beam in the optical reflection cavity 100 is within the light transmission plane xz, the optical reflection cavity 100 can adopt a flat shape.

[0105] Example 2

[0106] like Figure 6 As shown, in one embodiment, based on Embodiment 1, the optical reflecting cavity 100 further includes:

[0107] The drive mechanism 117 is used to drive the tilting sub-reflector 105 to move back and forth periodically along the Z-axis during each data acquisition process in the gas absorption data detection process.

[0108] In the detection process, the input wavelength of the light beam varies in a preset wavelength range, and the wavelength of the detection light beam is controlled to remain constant or to vary in a preset wavelength modulation range in each data acquisition process, so that the spectral transmittance function can be obtained by signal processing according to the actual light intensity of the interference light beam corresponding to the detection light beam at each wavelength output from the output end in each data acquisition process. The preset wavelength range and the preset wavelength modulation range can be set according to actual needs. For example, the preset wavelength range is 0.2um-12um from the ultraviolet wavelength to the mid-infrared wavelength, and the wavelength of the detection light beam after modulation in the preset wavelength modulation range is still in the preset wavelength range.

[0109] In application, the driving mechanism 117 can be implemented based on a piezoelectric ceramic type or an electromagnetic type driver. In the detection process, the wavelength of the detection light beam varies in a preset wavelength range, and the wavelength of the detection light beam is controlled to remain constant or to vary in a preset wavelength modulation range in each data acquisition process, so that the spectral transmittance function can be obtained by signal processing according to the actual light intensity of the interference light beam corresponding to the detection light beam at each wavelength output from the output end in each data acquisition process. The preset wavelength range and the preset wavelength modulation range can be set according to actual needs. For example, the preset wavelength range is 0.2um-12um from the ultraviolet wavelength to the mid-infrared wavelength, and the wavelength of the detection light beam after modulation in the preset wavelength modulation range is still in the preset wavelength range.

[0110] In one embodiment, the Z-axis direction includes parallel and opposite Z-axis positive direction and Z-axis negative direction;

[0111] The position change value of the tilt sub-mirror 105 along the Z-axis positive direction is positive;

[0112] The position change value of the tilt sub-mirror 105 along the Z-axis negative direction is negative;

[0113] When the tilt sub-mirror 105 moves periodically along the Z-axis direction,

[0114] Wherein, δ represents the position change value of the tilt sub-mirror 105 in the Z-axis direction, λ represents the input wavelength of the light beam, and λ is a variable varying in a preset wavelength range in the entire detection process, and λ remains constant or varies in a preset wavelength modulation range in each data acquisition process.

[0115] In application, the range of the sum of the position change values of the tilt sub-mirror 105 in the Z-axis direction is 0.25-10 times the wavelength of the detection light beam, which can be set according to actual needs.

[0116] The embodiment of the present application can obtain the interference beams of the tilted sub-mirror 105 at different positions at the output end 102 without significantly increasing the volume of the optical reflection cavity 100, based on the periodic reciprocating movement of the driving mechanism 117 along the Z-axis direction parallel to the optical axis 108 in each data acquisition process of the detection process of the gas absorption data. Based on the interference beams, the gas absorption data with smooth optical noise can be obtained, thereby improving the sensitivity when detecting the gas absorption data based on the optical reflection cavity 100.

[0117] Embodiment three

[0118] As shown in Figure 7 , Figure 8 or Figure 9 The embodiment of the present application provides an optical reflection cavity 200, comprising:

[0119] an input end 201 for inputting a light beam;

[0120] an output end 202 for outputting the light beam;

[0121] a main concave mirror 203, wherein the input end 201 is located at the long axis center line 203a of the main concave mirror 203; and

[0122] two sub-concave mirrors 204 and 205, wherein the curvature center of the main concave mirror 203 is located on the line 206 between the long axis centers of the two sub-concave mirrors 204 and 205, and the optical axis 207 of the optical reflection cavity 200 is perpendicular to the focal plane of the main concave mirror 203;

[0123] wherein the output end 202 is located at the long axis center line 203a of the main concave mirror 203 or the long axis center line 204a (not shown in the figure) or 205a (not shown in the figure) of any sub-concave mirror 204 or 205;

[0124] The light beam is input from the input end 201 into the light transmission plane xz, and is output from the output end 202 after multiple reflections between the main concave mirror 203 and the two sub-concave mirrors 204 and 205 in the light transmission plane xz, wherein the light transmission plane xz is the plane where the long axis center line 203a of the main concave mirror 203 and the long axis center lines 204a and 205a of the two sub-concave mirrors 204 and 205 are located.

[0125] In application, the long axis center line 203a is the center line of the main concave mirror 203 parallel to the long axis of the main concave mirror 203, the long axis center line 204a is the center line of the sub-concave mirror 204 parallel to the long axis of the sub-concave mirror 204, and the long axis center line 205a is the center line of the sub-concave mirror 205 parallel to the long axis of the sub-concave mirror 205. Taking the three-dimensional Cartesian coordinate system XYZ as an example, the long axis of the main concave mirror 203 and the long axis center line 203a are parallel to the X-axis direction of the three-dimensional Cartesian coordinate system XYZ, the optical axis 207 is parallel to the Z-axis direction of the three-dimensional Cartesian coordinate system XYZ, and the long axis of the sub-concave mirror 204 and the long axis center line 204a, the long axis of the sub-concave mirror 205 and the long axis center line 205a, and the light transmission plane xz are all in the XZ plane of the three-dimensional Cartesian coordinate system XYZ.

[0126] In application, the output end 202 can be arranged on the main concave mirror 203, the sub-concave mirror 204 or 205. The sizes of the two sub-concave mirrors 204 and 205 can be the same or different, which can be set according to actual needs. Figure 7 Figure 8 and Figure 9 In the examples shown in FIGS. 1 to 3, the input end 201 and the output end 202 are arranged on the main concave mirror 203, and the sizes of the two sub-concave mirrors 204 and 205 are the same.

[0127] In one embodiment, the long axis of the sub-concave mirror 204 and the long axis center line 204a, and the long axis of the sub-concave mirror 205 and the long axis center line 205a are parallel to the X-axis direction or have a certain angle with the X-axis direction. Figure 7 Figure 8 and Figure 9 In the examples shown in FIGS. 4 to 6, the long axis of the sub-concave mirror 204 and the long axis center line 204a, and the long axis of the sub-concave mirror 205 and the long axis center line 205a have a certain angle with the X-axis direction.

[0128] Figure 7 Figure 8 and Figure 9 In the examples shown in FIGS. 7 to 9, the optical reflection cavity 200 is a White room composed of three concave mirrors with the same curvature radius and focal length f. The main concave mirror 203 is located on one side, the two sub-concave mirrors 204 and 205 are located on the opposite side of the main concave mirror 203, and the input end 201 and the output end 202 are located on both sides of the main concave mirror 203. The two sub-concave mirrors 204 and 205 have a certain inclination angle, and the distance between the main concave mirror 203 and the two sub-concave mirrors 204 and 205 is set to 2f. The light beam is reflected multiple times between the main concave mirror 203 and the two sub-concave mirrors 204 and 205 to form an image, and finally output from the side of the main concave mirror 203.​​​

[0129] As shown in FIG. 1, the input end 201 is a first fiber collimator with a first fiber stub, and the output end 202 is a second fiber collimator with a second fiber stub. The light beam is inputted through the first fiber collimator and outputted through the second fiber collimator. Figure 10 As shown in FIG. 2, the input end 201 is a first fiber collimator array with a first fiber stub array, and the output end 202 is a second fiber collimator array with a second fiber stub array. The light beam is inputted through the first fiber collimator array and outputted through the second fiber collimator array.

[0130] In one embodiment, the input end 201 is a first fiber collimator with a first fiber stub, and the light beam is inputted through the first fiber collimator;

[0131] Alternatively, the input end 201 is a first fiber collimator array with a first fiber stub array, and the light beam is inputted through the first fiber collimator array;

[0132] Alternatively, the input end 201 is a through hole or an opening angle on the primary concave mirror 203, and the light beam is inputted from free space into the input end 201;

[0133] Alternatively, the input end 201 is connected to a light emitting device through an optical fiber, and the light beam is inputted from the light emitting device;

[0134] The output end 202 is a second fiber collimator with a second fiber stub, and the light beam is outputted through the second fiber collimator;

[0135] Alternatively, the output end 202 is a second fiber collimator array with a second fiber stub array, and the light beam is outputted through the second fiber collimator array;

[0136] Alternatively, the output end 202 is a through hole or an opening angle on the primary concave mirror 203 or any of the sub-concave mirrors 204 or 205, and the light beam is outputted from the output end 202 to free space;

[0137] Alternatively, the output end 202 is connected to a light sensing device through an optical fiber, and the light beam is received by the light sensing device;

[0138] Alternatively, the output end 202 is connected to a light sensing device array through an optical fiber, and the light beam is received by the light sensing device array.

[0139] In applications, the through hole and the opening angle are suitable for non-coherent light beams with large divergence angles. For coherent light beams with small divergence angles, such as laser, the input end is selected as a fiber collimator with a fiber stub, and the output end is correspondingly selected as a fiber collimator with a fiber stub, or a light sensing device is selected to directly receive the light beam.

[0140] The optical reflecting cavity 200 provided in this embodiment of the application, by positioning the input end 201 at the center line 203a of the major axis of the main concave mirror 203, positioning the center of curvature of the main concave mirror 203 at the line 206 connecting the centers of the major axes of the two sub-concave mirrors 204 and 205, and positioning the output end 202 at the center line 203a of the major axis of the main concave mirror 203 or the center line 204a or 205a of the major axis of any of the sub-concave mirrors 204 or 205, allows a light beam to be output from the input end 201. The light beam enters the optical transmission plane xz, which contains the major axis centerline 203a of the main concave mirror 203 and the major axis centerlines 204a and 205a of the two sub-concave mirrors 204 and 205. After multiple reflections between the main concave mirror 203 and the two sub-concave mirrors 204 and 205 within the optical transmission plane xz, it is output from the output end 202. Since the reflected light path of the light beam in the optical reflection cavity 200 is within the optical transmission plane xz, the optical reflection cavity 200 can adopt a flat shape.

[0141] Example 4

[0142] like Figure 11 As shown, in one embodiment, based on Embodiment 3, the optical reflecting cavity 200 further includes:

[0143] The drive mechanism 209 is used to drive M sub-concave mirrors to periodically reciprocate along the Z-axis direction during each data acquisition process in the gas absorption data detection process. The Z-axis direction is parallel to the optical axis of the optical system composed of the main concave mirror 203 and the two sub-concave mirrors 204 and 205.

[0144] Where M≥1, the detection process is as follows: with the gas to be detected filled in the optical reflection cavity 200, the light beam is input into the light transmission plane xz from the input end 201. After multiple reflections between the main concave reflector 203 and the two sub-concave reflectors 204 and 205 in the light transmission plane xz, it is output from the output end 202. During the entire detection process, the input wavelength of the light beam changes within the preset wavelength range. During each data acquisition process, the input wavelength of the light beam is constant or changes within the preset wavelength modulation range.

[0145] In application, the driving mechanism 209 can be implemented based on a piezoelectric ceramic type or an electromagnetic type driver. In the detection process, the wavelength of the detection light beam varies within a preset wavelength range, and the wavelength of the detection light beam is controlled to remain constant or vary within a preset wavelength modulation range during each data acquisition process, so that the spectral transmittance function can be obtained by signal processing according to the actual light intensity of the interference light beam corresponding to the detection light beam at each wavelength output from the output end 202 during each data acquisition process. The preset wavelength range and the preset wavelength modulation range can be set according to actual needs. For example, the preset wavelength range is 0.2um-12um from the ultraviolet wavelength to the mid-infrared wavelength, and the wavelength of the detection light beam after modulation within the preset wavelength modulation range is still within the preset wavelength range.

[0146] In application, the driving mechanism 209 can include a motor and a driver, the motor is used for mechanical connection with the sub-mirror to be driven, and the driver is used for electrical connection with the motor to drive the motor to move. The driver can be a piezoelectric ceramic driver, a micro-electromechanical system driver, a magnetostrictive driver, or a voice coil motor driver.

[0147] In application, the driving mechanism 209 can be used to drive the sub-concave mirror 204 or 205 to move alone, or can be used to drive the sub-concave mirrors 204 and 205 to move simultaneously. When the driving mechanism 209 drives the sub-concave mirrors 204 and 205 simultaneously, the driving mechanism 209 can include two drivers for driving the sub-concave mirrors 204 and 205 respectively.

[0148] Figure 11 The input end 201 and the output end 202 are both arranged on the main concave mirror 203, the two sub-concave mirrors 204 and 205 have the same size, and the driving mechanism 209 is used to drive the sub-concave mirror 204 to move alone. The long axis of the sub-concave mirror 204 and the long axis center line 204a (not shown in the figure), and the long axis of the sub-concave mirror 205 and the long axis center line 205a (not shown in the figure) are all in the same direction as the X-axis direction.

[0149] In one embodiment, the Z-axis direction includes parallel and opposite Z-axis positive direction and Z-axis negative direction;

[0150] The position change value of the sub-concave mirror 204 or 205 when moving along the Z-axis positive direction is positive;

[0151] The position change value of the sub-concave mirror 204 or 205 when moving along the Z-axis negative direction is negative;

[0152] When the M sub-concave mirrors move periodically and reciprocally along the Z-axis direction,

[0153] Wherein, δ represents the sum of the position change values of the M sub-concave mirrors in the Z-axis direction, λ represents the input wavelength of the light beam, and λ is a variable changing in a preset wavelength range during the entire detection process, and λ remains constant or changes in a preset wavelength modulation range during each data acquisition process.

[0154] In applications, the range of the sum of the position change values of the M sub-concave mirrors in the Z-axis direction driven by the driving mechanism 209 is 0.25-10 times the wavelength of the detection light beam, which can be set according to actual needs.

[0155] The optical reflection cavity 200 provided by the embodiment of the present application can change the distance between the optical center of the sub-concave mirror and the main concave mirror 203 opposite to it by driving the M sub-concave mirrors to periodically reciprocate along the Z-axis direction by the driving mechanism 209 during each data acquisition process of the detection process of the gas absorption data, so as to change the single light path of the detection light beam when reflected between the M sub-concave mirrors and the main concave mirror 203 opposite to them, so that the interference light beams at different positions of the M sub-concave mirrors can be obtained at the output end. Based on these interference light beams, the gas absorption data with smooth optical noise can be obtained, so as to improve the sensitivity when detecting the gas absorption data based on the optical reflection cavity 200.

[0156] Embodiment five

[0157] As shown in Figure 12 , the flat light path gas chamber 300 can include the optical reflection cavity 100 (not shown in the figure) in the embodiment one or the embodiment two. In this case, the width L x , the height L y and the length of the flat light path gas chamber 300 are respectively parallel to the long axis of the main plane mirror 104, the short axis of the main plane mirror 104 and the optical axis 108.

[0158] Alternatively, the flat light path gas chamber 300 can also include the optical reflection cavity 200 (not shown in the figure) in the embodiment three or the embodiment four. In this case, the width L x , the height L y and the length of the flat light path gas chamber 300 are respectively parallel to the long axis of the main concave mirror 203, the short axis of the main concave mirror 203 and the optical axis 207.

[0159] Figure 12 The spot trajectory 301 in the flat light path gas chamber 300 is shown as a single straight line arranged along the width direction of the flat light path gas chamber 300 in the example shown in Figure 12All hollow circles). The single-row straight arrangement of the spot trajectory 301 in the flat optical path gas chamber 300 makes the flat optical path gas chamber 300 adopt a flat shape with a small height-width ratio (i.e., the height L y is much smaller than the width L x , and the length is determined by the length of the optical reflection cavity 100 or 200 in the direction of the optical axis 108 or 207.

[0160] In an embodiment, the height-width ratio of the flat optical path gas chamber 300 is less than or equal to 1 / 4.

[0161] In applications, the height-width ratio of the flat optical path gas chamber 300 can be set to any ratio less than or equal to 1 / 4 according to actual needs, for example, 1 / 4, 1 / 5, 1 / 6, 1 / 8, etc.

[0162] The flat optical path gas chamber 300 provided by the embodiments of the present application adopts the optical reflection cavity 100 or 200. Since the reflected light path of the light beam in the optical reflection cavity 100 or 200 is in the light transmission plane xz, the optical reflection cavity 100 or 200 can adopt a flat shape, so that the width, height and length of the flat optical path gas chamber 300 can be parallel to the long axis of the main plane mirror 104, the short axis of the main plane mirror 104 and the optical axis 108 in the optical reflection cavity 100, or parallel to the long axis of the main concave mirror 203, the short axis of the main concave mirror 203 and the optical axis 207 in the optical reflection cavity 200, so that the flat optical path gas chamber 300 can also adopt a flat shape.

[0163] As shown in Figure 12 or Figure 13 In an embodiment, the flat optical path gas chamber 300 includes a sealed gas chamber body 305, and any side wall of the sealed gas chamber body 305 is provided with a gas inlet 306 and a gas outlet 307. The gas inlet 306 and the gas outlet 307 do not pass through the transmission light path of the light beam.

[0164] As shown in Figure 12 , the optical reflection cavity 100 or 200 is located in the sealed gas chamber body 305; or as shown in Figure 13 , the sealed gas chamber body 305 is located in the optical reflection cavity 100 or 200 (not shown in the figure), and the sealed gas chamber body 305 is provided with a light transmission window 308 parallel to the two side walls in the direction of the optical axis of the optical reflection cavity 100 or 200. The light transmission window 308 is used for input and output of the light beam.

[0165] In applications, the gas inlet 306 and the gas outlet 307 can be arranged on the same side wall or different side walls.

[0166] In an embodiment, the gas inlet 306 and the gas outlet 307 are arranged on any side wall of the sealed gas chamber body 305 perpendicular to the direction of the optical axis.

[0167] As shown in Figure 13 the same side wall of the sealed gas chamber body 305 perpendicular to the optical axis direction.

[0168] The embodiment of the present application places the sealed gas chamber body 305 inside the optical reflection cavity 100 or 200, sets the light-transmitting window 308 on the two side walls of the sealed gas chamber body 305 parallel to the optical axis direction of the optical reflection cavity 100 or 200 for light beam input and output, and sets the gas inlet 306 and the gas outlet 307 on any side wall of the sealed gas chamber body 305, so that the gas inlet 306 and the gas outlet 307 do not pass through the transmission light path of the light beam, which can avoid the influence of the corrosion or pollution of the to-be-detected gas (for example, corrosive gas or water vapor, dust and the like mixed in the gas) and the temperature change of the sealed gas chamber body on the reflecting element of the optical reflection cavity 100 or 200.

[0169] In one embodiment, the flat optical path gas chamber 300 further comprises a temperature adjusting component (not shown in the figure) wrapped on any outer side wall of the sealed gas chamber body 305 and not passing through the transmission light path of the light beam, which is used to adjust the temperature of the to-be-detected gas in the case that the optical reflection cavity 100 or 200 is filled with the to-be-detected gas.

[0170] In application, the temperature adjusting component comprises at least one of a heating film and a cooling film, wherein the heating film is used to heat the outer side wall of the sealed gas chamber body 305 wrapped by the heating film, and the cooling film is used to cool the outer side wall of the sealed gas chamber body 305 wrapped by the cooling film, so as to realize the heating or cooling of the to-be-detected gas through the heat exchange between the sealed gas chamber body 305 and the to-be-detected gas.

[0171] In the embodiment of the present application, the temperature adjusting component is wrapped on any outer side wall of the sealed gas chamber body 305 and not passing through the transmission light path of the light beam, which is used to adjust the temperature of the to-be-detected gas in the case that the optical reflection cavity 100 or 200 is filled with the to-be-detected gas. Since the flat optical path gas chamber 300 can adopt a flat form, the heat exchange efficiency between the sealed gas chamber body 305 and the to-be-detected gas can be improved, so that the temperature adjusting efficiency of the flat optical path gas chamber 300 can be improved, and the temperature stability and temperature uniformity of the optical element and the to-be-detected gas in the flat optical path gas chamber 300 are also improved. In the case that the sealed gas chamber body 305 is located inside the optical reflection cavity 100 or 200, since the reflecting element of the optical reflection cavity 100 or 200 is far away from the sealed gas chamber body 305, the influence of the temperature change of the sealed gas chamber body 305 and the corrosion or pollution of the to-be-detected gas on the reflecting element can be avoided.

[0172] The above only describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An optical resonator cavity, characterized by, The application relates to an optical cavity, which comprises: an input end for inputting a light beam; an output end for outputting the light beam, the input end being arranged separately from the output end; a main plane mirror, the input end and the output end being located on a long-axis center line of the main plane mirror; a concave mirror, the concave mirror having a focal plane, the distance from the focal plane to the concave mirror being a focal length f of the concave mirror, the long-axis center line intersecting an optical axis of an optical system formed by the main plane mirror and the concave mirror; and a tilted sub-mirror, the tilted sub-mirror being a plane mirror with an area smaller than that of the main plane mirror, the normal line of the tilted sub-mirror and the normal line of the main plane mirror forming a tilt angle theta 1, the tilt angle theta 1 being non-zero, and the tilt angle theta 1 being located on an optical transmission plane, the optical transmission plane being a plane formed by the long-axis center line and the optical axis; wherein the main plane mirror and the tilted sub-mirror are coplanar and located on the focal plane of the concave mirror; the light beam is input from the input end into the optical transmission plane, and is output from the output end after multiple reflections among the concave mirror, the main plane mirror and the tilted sub-mirror in the optical transmission plane. The application further comprises:

2. The optical resonator cavity of claim 1, wherein, a driving mechanism for driving the tilted sub-mirror to periodically move back and forth along a Z-axis direction during each data acquisition process of a detection process of gas absorption data, the Z-axis direction being parallel to the optical axis; wherein the detection process is that, when the optical cavity is filled with a gas to be detected, the light beam is input from the input end into the optical transmission plane, and is output from the output end after multiple reflections among the concave mirror, the main plane mirror and the tilted sub-mirror in the optical transmission plane, the input wavelength of the light beam varying within a preset wavelength range during the entire detection process, and the input wavelength of the light beam being constant or varying within a preset wavelength modulation range during each data acquisition process. The Z-axis direction comprises parallel and opposite Z-axis positive and negative directions; 3. The optical resonator cavity of claim 2, wherein, the position change value of the tilted sub-mirror along the Z-axis positive direction is positive; the position change value of the tilted sub-mirror along the Z-axis negative direction is negative; wherein delta represents the position change value of the tilted sub-mirror in the Z-axis direction, and lambda represents the input wavelength of the light beam. The tilt sub-mirror moves periodically back and forth along the Z-axis direction, The application relates to an optical cavity, which comprises:

4. An optical resonator cavity, characterized by, an input end for inputting a light beam; an output end for outputting the light beam; a main concave mirror, the input end being located on a long-axis center line of the main concave mirror; and two sub-concave mirrors, the curvature center of the main concave mirror being located on a line connecting the long-axis centers of the two sub-concave mirrors, and the optical axis of the optical cavity being perpendicular to the focal plane of the main concave mirror; wherein the output end is located on the long-axis center line of the main concave mirror or the long-axis center line of any one of the sub-concave mirrors. ​ ​ The light beam is input from the input end into a light transmission plane, and is output from the output end after multiple reflections between the main concave mirror and the two sub-concave mirrors in the light transmission plane, the light transmission plane being a plane in which a long axis center line of the main concave mirror and long axis center lines of the two sub-concave mirrors are located.

5. The optical resonator cavity of claim 4, wherein, Further comprising: a driving mechanism for driving the M sub-concave mirrors to periodically move back and forth along a Z-axis direction during each data acquisition process of a detection process of gas absorption data, the Z-axis direction being parallel to an optical axis of an optical system composed of the main concave mirror and the two sub-concave mirrors; wherein M≥1, the detection process being that, in a case where the optical reflection cavity is filled with a gas to be detected, the light beam is input from the input end into the light transmission plane, and is output from the output end after multiple reflections between the main concave mirror and the two sub-concave mirrors in the light transmission plane, the input wavelength of the light beam varying within a preset wavelength range during the entire detection process, and the input wavelength of the light beam being constant or varying within a preset wavelength modulation range during each data acquisition process.

6. The optical resonator cavity of claim 5, wherein, The Z-axis direction includes parallel and opposite Z-axis positive direction and Z-axis negative direction; The position change value of the sub-concave mirror when moving along the Z-axis positive direction is positive; The position change value of the sub-concave mirror when moving along the Z-axis negative direction is negative; When the two sub-concave mirrors move periodically back and forth along the Z-axis direction, Wherein, δ represents the sum of the position change values of the M sub-concave mirrors in the Z-axis direction, and λ represents the input wavelength of the light beam.

7. A flat optical path gas cell characterized by, The optical reflection cavity comprises the flat optical path gas chamber, the width, height and length of the flat optical path gas chamber being parallel to the long axis of the main plane mirror, the short axis of the main plane mirror and the optical axis, respectively. Alternatively, the optical reflection cavity comprises the flat optical path gas chamber, the width, height and length of the flat optical path gas chamber being parallel to the long axis of the main concave mirror, the short axis of the main concave mirror and the optical axis, respectively.

8. The flat-path gas cell of claim 7, wherein, The sealed gas chamber body is further provided with an air inlet and an air outlet on any side wall thereof, the air inlet and the air outlet not passing through the transmission light path of the light beam; The optical reflection cavity is located in the sealed gas chamber body, or the sealed gas chamber body is located in the optical reflection cavity, the sealed gas chamber body being provided with light transmission windows on two side walls parallel to the optical axis direction of the optical reflection cavity, the light transmission windows being used for input and output of the light beam.

9. The flat-path gas cell of claim 8, wherein, The temperature adjusting component is further provided on any outer side wall of the sealed gas chamber body and does not pass through the transmission light path of the light beam, and is used for adjusting the temperature of the gas to be detected in a case where the optical reflection cavity is filled with the gas to be detected.

10. A flat-path gas cell as claimed in any one of claims 7 to 9, characterised in that, The ratio of the height to the width of the flat optical path gas chamber is less than or equal to 1 / 4.

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