CN111982817A - Optical path-variable multiple reflection pool and optical path adjusting method - Google Patents
Optical path-variable multiple reflection pool and optical path adjusting method Download PDFInfo
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Abstract
The application provides a variable optical path multiple reflection cell and an optical path adjusting method. The reflecting pool includes: an absorption air chamber, an optical window and a reflector; the absorption gas chamber comprises a quartz cavity, a stepped spiral cavity and a differential spiral cavity which are connected in sequence; the stepped spiral cavity is formed by a stepped spiral structure, and the stepped spiral structure comprises a lower stepped spiral structure, an upper stepped spiral structure and a middle stepped spiral structure which are connected in sequence; the differential screw cavity is composed of a differential screw structure, and the differential screw structure comprises an upper differential screw structure, a middle differential screw structure and a lower differential screw structure which are connected in sequence; the reflector comprises two confocal concave reflectors with the same focal length and fixed at the front end and the rear end of the absorption air chamber. The distance between the two reflectors is adjusted through the ladder spiral structure and the differential spiral structure, and then the optical path is adjusted. The optical path adjusting device has the characteristics of simple structure, accurate and adjustable optical path and high stability.
Description
Technical Field
The invention relates to the technical field of gas detection, in particular to a variable optical path multiple reflection cell and an optical path adjusting method.
Background
In many research fields and monitoring applications, low-concentration gases can be accurately measured using laser spectroscopy, wherein tunable laser absorption spectroscopy (TDLAS) based gas absorption cells has the advantages of high sensitivity, high accuracy, etc. in measuring gases. Some absorption cells commonly used in the TDLAS system include White type, matrix type and Herriott type, and the White type and the matrix type are characterized in that the aperture angle is larger, so that more reflection times can be realized, but more reflection mirrors are used; the Herriott type absorption cell is based on the principle that incident light is limited to be reflected back and forth between two or more reflecting mirrors coated with high-reflectivity films, so that the effective optical path of interaction between light and a substance is increased, namely, absorption spectrum signals with high signal-to-noise ratio are obtained by increasing the absorption capacity of detected molecules to the incident light. Compared with the first two Herriott types, the Herriott type laser has the advantages of simple structure, small volume and relatively easily adjustable light path, and is suitable for laser sources.
In practical application, due to different detection environments, higher requirements are put on the gas absorption cell. For low-concentration gas detection, the absorption cell is required to have high sensitivity, and the absorption cell is required to be suitable for high-concentration gas detection, so that the reflection cell air chamber is required to be capable of adjusting the measuring range of the absorption cell according to different requirements, and the absorption cell can meet the requirements of different detection sensitivities and measuring ranges. For low concentrations of gas, in order to obtain smaller gas detection limits, one usually starts with both enhancing the absorption signal strength and suppressing noise. The main method for enhancing the intensity of the absorption signal is to increase the optical path, and according to the lambert-beer law, the longer the optical path means the stronger the absorption, and the higher the sensitivity of the detector. In the multi-reflection pool, noise can hardly be completely avoided, a light beam path can be changed in the process of adjusting the optical path, the influence of the noise on absorption measurement is different under different light beam paths, but at present, no exact model exists for the noise in the Herriott type multi-reflection pool. Therefore, in order to meet the requirements of different detection sensitivities and measuring ranges and to explore the influence of the optical path on the noise in the absorption cell, the optical path of the absorption cell needs to be adjustable.
Disclosure of Invention
The embodiment of the invention provides a variable optical path multiple reflection cell and an optical path adjusting method, which are used for meeting the requirements of different detection sensitivities and measuring ranges and researching the technical problem of influence of an optical path on noise in an absorption cell.
According to a first aspect of the embodiments of the present invention, there is provided a variable optical path multiple reflection cell, including: : an absorption air chamber, an optical window and a reflector;
the absorption gas chamber comprises a quartz cavity, a stepped spiral cavity and a differential spiral cavity which are connected in sequence, the quartz cavity and the stepped spiral cavity are fixedly connected through an intermediate plate, and the stepped spiral cavity is in threaded connection with the differential spiral cavity;
the absorption air chamber is provided with an air inlet and an air outlet;
the stepped spiral cavity is formed by a stepped spiral structure, and the stepped spiral structure comprises a lower stepped spiral structure, an upper stepped spiral structure and a middle stepped spiral structure which are connected in sequence;
the differential spiral cavity is formed by a differential spiral structure, and the differential spiral structure comprises an upper differential spiral structure, a middle differential spiral structure and a lower differential spiral structure which are connected in sequence;
the reflectors comprise two confocal concave reflectors with the same focal length and are fixed at the front end and the rear end of the absorption air chamber;
the reflector at the front end of the absorption air chamber is provided with an inlet hole;
the optical window is arranged at the front end of the front end reflector of the absorption air chamber.
Preferably, the intermediate plate, the stepped spiral cavity and the differential spiral cavity are all made of aluminum materials, and the inner cavity surface is subjected to blackening treatment.
Preferably, the aperture size of the reflecting hole is 1-3 mm.
Preferably, the mirror is made of quartz material.
Preferably, the reflecting surface of the reflector is plated with a gold film.
Preferably, the gold film is coated with SiO2And (3) a layer.
Preferably, the joints of the quartz cavity, the intermediate plate and the stepped spiral cavity are sealed by O-rings.
Preferably, the entry hole is disposed near an edge of the mirror.
Preferably, a laser adjusting frame is arranged above the reflecting pool and used for installing and adjusting the laser, a plane reflector support is further arranged at the front end of the reflecting pool and used for installing a plane reflector, and the plane reflector is used for reflecting the laser emitted by the laser into the optical window.
According to a second aspect of the embodiments of the present invention, there is provided a method for adjusting an optical length of a variable optical length multiple reflection cell, where the variable optical length multiple reflection cell provided in the first aspect of the embodiments of the present invention is utilized, the method including:
obtaining a reflector distance according to a preset optical path, wherein the optical path and the reflector distance satisfy the following relation:
in the formula: l is an optical path, P is a positive integer, d is a reflector spacing, d ranges from 0 to 4f (f is a focal length), R is a reflector curvature radius, R is a distance from the center of an incident hole to an optical axis, and A is equal to R2+r2，B＝t-2R；
Determining the reflection times according to the reflector spacing, wherein the relationship between the reflector spacing and the reflection times is as follows:
in the formula: n reflector spacing is P and is a positive integer, d is reflector spacing, the value range of d is 0-4 f (f is focal length), and R is reflector curvature radius;
determining a direction of incident light according to the mirror spacing, wherein a relationship that is satisfied between the mirror spacing and the direction of the incident light is:
in the formula: (x)0，y0) Is the position coordinate of an incident point, f is a focal length, d is a reflector spacing, and the value range of d is 0-4 f, (x'0，y’0) Is the incident angle of the light;
determining the position of each light spot on the reflector according to the direction of the incident light and the reflector spacing, wherein the relationship satisfied by the direction of the incident light, the reflector spacing and the position of each light spot on the reflector is as follows:
in the formula: (x)n，yn) For each spot position coordinate on the mirror, (x)0，y0) Is the position coordinate of an incident point, f is a focal length, d is a reflector spacing, and the value range of d is 0-4 f, (x'0，y’0) Theta is the included angle between two adjacent light spots as the incident angle of the light ray
Determining the position of an exit hole according to the reflection times;
an emergent hole is formed in the reflector of the reflecting pool according to the position of the emergent hole;
and adjusting the step spiral structure and the differential spiral structure of the reflecting pool according to the distance between the reflecting mirrors to obtain the optical path.
As can be seen from the above technical solutions, in the variable optical path multiple reflection cell and the optical path adjustment method provided in the embodiments of the present invention, the reflection cell includes: an absorption air chamber, an optical window and a reflector; the absorption gas chamber comprises a quartz cavity, a stepped spiral cavity and a differential spiral cavity which are connected in sequence, the quartz cavity and the stepped spiral cavity are fixedly connected through an intermediate plate, and the stepped spiral cavity is in threaded connection with the differential spiral cavity; the middle plate is provided with an air inlet and an air outlet; the stepped spiral cavity is formed by a stepped spiral structure, and the stepped spiral structure comprises a lower stepped spiral structure, an upper stepped spiral structure and a middle stepped spiral structure which are connected in sequence; the differential spiral cavity is formed by a differential spiral structure, and the differential spiral structure comprises an upper differential spiral structure, a middle differential spiral structure and a lower differential spiral structure which are connected in sequence; the reflectors comprise two confocal concave reflectors with the same focal length and are positioned at the front end and the rear end of the absorption air chamber; the optical window is arranged at the front end of the reflecting mirror at the front end of the absorption air chamber. The cavity length is roughly adjusted through the wider thread fit of the stepped spiral structure, and the cavity length is finely adjusted through the narrower thread fit of the differential spiral structure, so that the accurate adjustment of the reflector distance is realized, and the purpose that the optical distance can be accurately adjusted is realized because the optical distance and the reflector distance have clear corresponding relation.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
Fig. 1 is a schematic cross-sectional structural diagram of a variable optical path multiple reflection cell according to an embodiment of the present invention;
fig. 2 is a schematic perspective view of a variable optical path multiple reflection cell according to an embodiment of the present invention;
FIG. 3 is a schematic view of an assembly of a stepped helical structure according to an embodiment of the present invention;
FIG. 4 is a schematic view of a differential screw structure assembly according to an embodiment of the present invention;
fig. 5 is a schematic perspective view of another variable optical path multiple reflection cell according to an embodiment of the present invention;
fig. 6 is a schematic basic flow chart of a method for adjusting an optical path of a variable optical path multiple reflection cell according to an embodiment of the present invention;
FIG. 7 shows an incident direction of x'0＝0.06723，y′0(ii) spot profile on B mirror at-0.06802;
FIG. 8 is a graph of the spot profile of mirror A according to an embodiment of the present invention, (a) reflected 58 times, (b) reflected 118 times;
fig. 9 is a schematic diagram of the spot size provided by the embodiment of the present invention, (a) theoretical calculation, (b) simulation software;
fig. 10 is a graph showing the relationship between the number of reflections and the distance between mirrors (f is 100mm) according to an embodiment of the present invention;
fig. 11 is a graph of the relationship between the number of reflections and the mirror pitch when k is ± 2 (f is 100mm), according to an embodiment of the present invention;
FIG. 12 is a graph of optical path and mirror spacing provided by an embodiment of the present invention;
FIG. 13 is a diagram of the distribution of light spots for a mirror spacing of 193.8mm according to an embodiment of the present invention, (a) mirror A, (B) mirror B;
FIG. 14 is a diagram of the distribution of light spots for a spacing of 206.5mm for mirrors provided by an embodiment of the present invention (a) mirror A and (B) mirror B;
FIG. 15 is a diagram showing the distribution of light spots when the distance between the mirrors is 398.4mm according to the embodiment of the present invention, wherein (a) the mirror A and (B) the mirror B are shown.
Description of reference numerals:
1-an absorption air chamber; 11-a quartz chamber; 12-a stepped spiral cavity; 120-step helix structure; 121-a stepped down helix structure; 122-a stepped helical structure; 123-upper step spiral structure; 13-differential helical cavity; 130-differential helical structure; 131-an upper differential helical structure; 132-medium differential helical structure; 133-lower differential helical structure; 2-an optical window; 3-a mirror; 4-a middle plate; 5-an air inlet; 6-air outlet; 7-entering a perforation; 8-laser adjusting frame; 9-plane mirror support; 10-cage bars.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic cross-sectional structure diagram of a variable optical path multiple reflection cell according to an embodiment of the present invention, fig. 2 is a schematic three-dimensional structure diagram of a variable optical path multiple reflection cell according to an embodiment of the present invention, fig. 3 is a schematic diagram of a stepped spiral structure assembly according to an embodiment of the present invention, fig. 4 is a schematic diagram of a differential spiral structure assembly according to an embodiment of the present invention, fig. 5 is a schematic three-dimensional structure diagram of another variable optical path multiple reflection cell according to an embodiment of the present invention, and the variable optical path multiple reflection cell according to an embodiment of the present invention is further described below with reference to fig. 1 to 5.
As shown in fig. 1-2, the variable optical path multiple reflection cell includes: absorption gas chamber 1, optical window 2, reflector 3. The absorption gas chamber 1 comprises a quartz cavity 11, a stepped spiral cavity 12 and a differential spiral cavity 13 which are connected in sequence, wherein the quartz cavity 11 and the stepped spiral cavity 12 are fixedly connected through an intermediate plate 4, and the stepped spiral cavity 12 and the differential spiral cavity 13 are in threaded connection. An air inlet 5 and an air outlet 6 are provided on the absorption air chamber 1, and preferably an air inlet 5 and an air outlet 6 are provided on the intermediate plate 4. As shown in fig. 3, the stepped spiral cavity 12 is formed by a stepped spiral structure 120, and the stepped spiral structure includes a lower stepped spiral structure 121, a stepped spiral structure 120, an upper stepped spiral structure 123, and a middle stepped spiral structure 122, which are connected in sequence, the stepped spiral structure 120. As shown in fig. 4, the differential spiral cavity 13 is formed by a differential spiral structure 130, and the differential spiral structure 130 includes an upper differential spiral structure 131, a middle differential spiral structure 132, a differential spiral structure 130, and a lower differential spiral structure 133, which are connected in sequence, and the differential spiral structure 130. The reflecting mirror 3 comprises two confocal concave reflecting mirrors 3 with the same focal length, the reflecting mirrors 3 are fixed at the front end and the rear end of the absorption air chamber 1, and for convenience of subsequent description, the reflecting mirror 3 at the front end of the absorption air chamber 1 is defined as an A mirror, and the reflecting mirror 3 at the rear end of the absorption air chamber 1 is defined as a B mirror. The optical window 2 is provided at the front end of the front end mirror 3 (mirror a) of the absorption gas chamber 1. In the assembling process, the optical axes of the two concave reflectors 3 are required to be overlapped with each other, but in the machining process, certain errors can be inevitably generated to cause the optical axes of the two concave reflectors 3 to deviate to some extent, and the positions of the concave mirrors need to be finely adjusted at the moment.
As a preferred embodiment provided by the embodiment of the present application, the intermediate plate 4, the stepped spiral cavity 12, and the differential spiral cavity 13 are all made of aluminum material, and the inner cavity surface is subjected to blackening treatment, so that the corrosion resistance is good, and the adsorptivity to gas is small.
The aperture of the incident hole 7 also has an influence on the number of reflections, and the incident hole 7 is too large, which may cause light leakage, and the like, and in a preferred embodiment provided in the present application, the aperture size of the reflection hole is 1-3mm, and more preferably 2 mm.
The lower limit of the optical path is a single optical path, the upper limit of the optical path has a close relation with the power of the incident light and the mirror reflectivity, the preferred implementation manner provided by the embodiment of the application is that the reflecting mirror 3 is made of quartz material, the reflecting surface is plated with a gold film to improve the reflectivity, and the gold film is provided with SiO2The layer can prevent the gold film from being damaged by corrosive gas such as acid or alkali. The reflectivity of the reflector 3 with a gold-plated mirror surface is generally over 99 percent.
The light intensity of laser in vacuum (no particle state) needs to be measured before measuring the particle concentration, which requires that the multi-path absorption cell has good sealing property. The specific gas is subjected to a gas detection experiment, and a vacuumizing and ventilating process is required, so that certain gas tightness requirements are required for the multi-reflection cell device. According to a preferred implementation mode provided by the embodiment of the application, the joints of the quartz cavity 11, the intermediate plate 4 and the stepped spiral cavity 12 are sealed by adopting O-shaped rings to increase the tightness of the air chamber, and the O-shaped rings are made of corrosion-resistant materials. The O-shaped sealing ring adopted by the device is sealed, and the radial sealing characteristic is that a radial gap is filled, so that axial circulation is blocked. The axial seal features fill axial voids, impeding radial flow. Because the radial seal does not need pretightening force, is more stable, has simple structure and convenient sealing, the radial seal structure is selected in the O-shaped ring seal structure mode. In the actual structure, a groove is reserved at the joint of the two ends of the cavity to place a sealing ring, so that the requirement of air chamber tightness is met.
In order to utilize the mirror surface more effectively and avoid the mutual interference of adjacent light spots, the position of the incident hole 7 should be as close to the edge of the reflector 3 as possible, so that the light spots are arranged more dispersedly.
In order to improve the integration of the device, as shown in fig. 5, a laser adjusting frame 8 is disposed above the reflecting pool, the laser adjusting frame 8 is used for installing and adjusting the laser, a plane mirror support 9 is further disposed at the front end of the reflecting pool, the plane mirror support 9 is used for installing a plane mirror, and the plane mirror is used for reflecting the laser emitted by the laser into the optical window 2. In addition, in order to avoid the phenomenon of light spot interference when obtaining more reflection times, a proper light source should be selected as much as possible, so that the size of the light spot is as small as possible.
As a preferred implementation mode provided by the embodiment of the application, the cage bars 10 are adopted to fasten the absorption gas chamber 1, the light window 2 and the reflector 3 of the multi-reflection cell. The portable multi-reflection pool is required to be as small as possible, and the size of the mechanical fixing support is reduced as much as possible according to the size of the concave mirror in the design process.
Theory is combined with reality, and specific dimensions need to be repeatedly modified in the design process to meet the actual processing requirements, so that the processing of the mechanical fixing support can meet the requirements. The design adopts CAD software to carry out mechanical design, can generate visible three-dimensional stereograms and engineering drawings, and can carry out simulated assembly on each part to check the feasibility of the device. The fixed support comprises 44 parts, and mainly comprises a quartz cavity 11, an incident structure assembly body, a laser adjusting frame 8, a cavity length adjusting assembly body, a cage rod 10 and the like.
The working principle of the variable optical path multiple reflection cell is as follows:
by adjusting the length of the reflecting pool, the distance between the front end reflector 3 and the rear end reflector 3 of the absorption air chamber 1 is changed, and the back-and-forth reflection times of the light beam between the two reflectors 3 are further changed, so that the purpose of adjusting the optical path is achieved. As shown in fig. 1, the adjusting structure is used as a part of the cavity and is divided into two major parts, namely a stepped spiral structure 120 and a differential spiral structure 130, wherein the stepped spiral structure 120 comprises three parts, namely an upper stepped spiral structure, a middle stepped spiral structure and a lower stepped spiral structure, and the main function is to roughly adjust the length of the cavity through the matching of threads with wider thread pitches; the differential screw comprises an upper differential screw structure, a middle differential screw structure and a lower differential screw structure, and the main function is to finely adjust the length of the cavity through the matching of threads with narrow thread pitches. By rotating the middle step spiral structure 122 and the middle differential spiral structure 132, the length of the cavity of the absorption air chamber 1 is increased or shortened step by step, and then the relative distance of the reflector 3 is changed, and the optical path of the absorption air chamber 1 can be adjusted.
And (3) analyzing the working principle of the spiral structure:
functional design objectives: the precise adjustment of the length of the multi-reflecting pool cavity in a larger range of centimeter level is realized.
The device comprehensively considers factors such as convenience and accuracy of adjustment, adopts a coarse and fine two-stage adjustment mode, and designs the cavity length adjusting structure.
(1) Coarse adjustment structure
As shown in fig. 3, a step-shaped helical structure 120 is designed, which is composed of an upper step-shaped helical structure 123, a middle step-shaped helical structure 122 and a lower step-shaped helical structure 121. According to the meshing principle of the thread turning directions, the same group of meshing threads are consistent in turning direction. The upper stepped screw structure 123 is a right-handed internal thread engaged with the right-handed external thread of the middle stepped screw structure 122, and the left-handed external thread of the lower stepped screw structure 121 is engaged with the left-handed internal thread of the middle stepped screw structure 122.
The two sets of threads have equal thread pitches and are single threads, and the lower stepped helical structure 121 is fixed. Let the externally applied torque when rotating the upper stepped screw structure 123 be M, and the rotational friction torque of the upper stepped screw structure 123 acting on the middle stepped screw structure 122 be M (f)1) The actual friction torque is M (f); the rotational friction torque of the middle step screw structure 122 acting on the lower step screw structure 121 is M (f)2) The actual friction torque is M (f'), M (f)1)＞M(f2). The rotation is a uniform variable speed movement with constant angular speed.
The following briefly describes the movement of the step-wise spiral structure 120.
Step one, the middle step spiral structure 122 is fixed, and the upper step spiral structure 123 is rotated clockwise with the clockwise direction of the observation direction as positive. The upper-stepped helical structure 123 is subjected to an externally applied torque M, and is subjected to a frictional torque-M (f) of the middle-stepped helical structure 122. M (f) ═ M (f)1)，M＝M(f1) And M-M (f) is equal to 0, the upper stepped spiral structure 123 rotates clockwise. Since the upper stepped screw structure 123 is engaged with the middle stepped screw structure 122 by the right-hand screw, the upper stepped screw structure 123 is fed in a clockwise direction from the start of the screw.
Step two, the fixed middle step spiral structure 122 is cancelled, and the upper step spiral structure 123 is rotated counterclockwise with the counterclockwise direction of the observation direction as positive. The upper-step helical structure 123 receives an externally applied torque M, and also receives a frictional torque-M (f) of the middle-step helical structure 122; the middle step screw structure 122 receives the friction torque M (f) from the upper step screw structure 123 and the friction torque-M (f') from the lower step screw structure 121. Because of M (f)1)＞M(f2) Then M (f) ═ M (f') ═ M (f)2) The middle step screw structure 122 rotates counterclockwise with respect to the lower step screw structure 121; m (f), the upper stepped spiral structure 123 and the middle stepped spiral structure 122 are relatively stationary. The middle step screw structure 122 is engaged with the lower step screw structure 121 via left-hand threads, so that the upper step screw structure123 will follow the mid-step helical formation 122 and will be fed in a clockwise direction from the start of the thread.
And step three, fixing the middle step spiral structure 122 again, and rotating the upper step spiral structure 123 counterclockwise by taking the counterclockwise direction of the observation direction as positive. In the same manner as the first step, the upper stepped spiral structure 123 is subjected to an externally applied torque M, and is subjected to a frictional torque-M (f) of the middle stepped spiral structure 122. M (f) ═ M (f)1)，M＝M(f1) And M-M (f) is equal to 0, the upper stepped spiral structure 123 rotates counterclockwise. Since the upper stepped screw structure 123 is engaged with the middle stepped screw structure 122 by the right-hand screw, the upper stepped screw structure 123 returns in the counterclockwise direction from the starting end of the screw.
And step four, canceling the fixed middle step spiral structure 122 again, and clockwise rotating the upper step spiral structure 123 by taking the clockwise direction of the observation direction as positive. Like the second step, the upper step screw structure 123 receives the externally applied torque M and the friction torque-M (f) of the middle step screw structure 122; the middle step screw structure 122 receives the friction torque M (f) from the upper step screw structure 123 and the friction torque-M (f') from the lower step screw structure 121. Because of M (f)1)＞M(f2) Then M (f) ═ M (f') ═ M (f)2) The middle step screw structure 122 rotates clockwise with respect to the lower step screw structure 121; m (f), the upper stepped spiral structure 123 and the middle stepped spiral structure 122 are relatively stationary. Since the middle step screw structure 122 is engaged with the lower step screw structure 121 by the left-hand screw, the upper step screw structure 123 returns along with the middle step screw structure 122 in the counterclockwise direction of the starting end of the screw.
(2) Fine adjustment structure:
as shown in fig. 4, the design is based on the principle of a differential screw structure 130, and the structure is composed of an upper differential screw structure 131, a middle differential screw structure 132, and a lower differential screw structure 133. The upper differential screw structure 131 and the middle differential screw structure 132 are engaged by right-handed screw threads with a pitch P1(ii) a The middle differential screw structure 132 and the lower differential screw structure 133 are also engaged by right-handed screw threads with a pitch P2，P1＞P2. Fixed upper differential screw structure131, the middle step screw structure 132 can rotate and translate, and the lower differential screw structure 133 can only translate.
The following briefly describes the movement of the differential screw structure 130 in steps.
Step one, the middle differential screw structure 132 rotates clockwise one circle according to the observation direction, and the middle differential screw structure 132 advances one pitch P relative to the upper differential screw structure 131 clockwise according to the starting end of the screw thread1The lower differential screw 133 is advanced by a pitch P in a clockwise direction with respect to the start of the screw2. Since the upper differential screw structure 131 is fixed and the lower differential screw structure 133 can translate, the lower differential screw structure 133 advances relative to the upper differential screw structure 131 in the clockwise direction of the starting end of the screw thread by a pitch difference P1-P2。
Step two, similarly to step one, rotating the middle differential helical structure 132 for one circle counterclockwise in the observation direction, and returning the middle differential helical structure 132 by one pitch P in the counterclockwise direction of the starting end of the thread with respect to the upper differential helical structure 1311The lower differential screw 133 is returned by a pitch P in the counterclockwise direction of the starting end of the screw thread2. Since the upper differential screw structure 131 is fixed and the lower differential screw structure 133 can translate, the return distance of the lower differential screw structure 133 relative to the upper differential screw structure 131 in the counterclockwise direction of the starting end of the screw thread is a screw pitch difference P1-P2。
Based on the above implementation principle, the method for adjusting the optical length of the variable optical length multiple reflection cell according to this embodiment will be described in detail below with reference to the accompanying drawings. Fig. 6 is a schematic basic flow chart of a method for adjusting an optical path of a variable optical path multiple reflection cell according to an embodiment of the present invention. As shown in fig. 6, the method specifically includes the following steps:
s1: obtaining the distance between the reflectors according to a preset optical path, wherein the optical path and the distance between the reflectors satisfy the following relation:
in the formula: l is an optical path, P is a positive integer, d is a reflector spacing, d ranges from 0 to 4f (f is a focal length), R is a reflector curvature radius, R is a distance from the center of an incident hole to an optical axis, and A is equal to R2+r2，B＝t-2R；
S2: determining the number of reflections according to the mirror spacing, the relationship between the mirror spacing and the number of reflections being:
in the formula: n reflector spacing is P and is a positive integer, d is reflector spacing, the value range of d is 0-4 f (f is focal length), and R is reflector curvature radius;
s3: determining the direction of the incident light according to the mirror spacing, wherein the relationship satisfied between the mirror spacing and the direction of the incident light is:
in the formula: (x)0，y0) Is the position coordinate of an incident point, f is a focal length, d is a reflector spacing, and the value range of d is 0-4 f, (x'0，y’0) Is the incident angle of the light;
s4: determining the position of each light spot on the reflector according to the direction of the incident light and the distance between the reflectors, wherein the relationship which is satisfied by the direction of the incident light, the distance between the reflectors and the position of each light spot on the reflector is as follows:
in the formula: (x)n，yn) For each spot position coordinate on the mirror, (x)0，y0) Is the position coordinate of an incident point, f is a focal length, d is a reflector spacing, and the value range of d is 0-4 f, (x'0，y’0) Theta is the included angle between two adjacent light spots as the incident angle of the light ray
S5: determining the position of an exit hole according to the reflection times;
s5: determining the position of an exit hole according to the reflection times;
s6: an emergent hole is arranged on the reflector of the reflecting pool according to the position of the emergent hole;
s7: and adjusting the stepped spiral structure and the differential spiral structure of the reflecting pool according to the distance between the reflecting mirrors to obtain the optical path.
The method for adjusting the optical path of the multiple reflection pool with the variable optical path provided by the embodiment of the application has the key points that a relational expression which is satisfied between the optical path and the distance between the reflection mirrors and a relational expression which is satisfied between the distance between the reflection mirrors and the reflection times are satisfied. According to a relation formula which is satisfied between the optical path and the distance between the reflecting mirrors, the distance between the reflecting mirrors in the reflecting pool which is actually needed to be adjusted for realizing the optical path can be obtained by a preset optical path; and determining the reflection times and the direction of incident light according to the distance between the reflectors so as to determine the position of the exit hole. The following describes in detail the process of determining the relationship between the optical path and the mirror pitch by analyzing and calculating the spot position distribution and the spot size.
(1) Light spot distribution rounding condition
For a Herriott type multiple reflection pool, two concave reflection mirrors of an air pool are parallel to each other, and in order to fully utilize the perimeter of the concave mirrors, light spots on the concave mirrors are designed to be circularly arranged, so that the interval between two adjacent light spots is as large as possible, light rays are prevented from overflowing in the reflection process in advance, a certain gap is reserved between the light spots, and interference between the light spots is avoided. As shown in FIG. 1, the reflector is placed on the x-y plane, and the direction vector of the incident light is (x'0，y′0，z′0) For simple calculation, z in the direction vector is set0Normalized to 1. To obtain a circularly distributed reflected light spot, the laser incident point is assumed to be (x)0，y0) And the slope of the incident light is x'0、y′0After n times of reflection, the intersection point of the light ray and the concave reflector is (x)n，yn) Two concave mirrors with focal length f, their centers are spaced by d.
Herriott et al obtained formula (1) according to Pierce's theorem:
the included angle theta between two adjacent light spots depends on the focal length f and the distance d of the concave reflecting mirror, and is shown as the formula (2):
when 0< d < 4f, the light can be reflected infinitely between the two mirrors without overflowing.
Converting expression (1) into expression (3)
xn＝Asin(nθ+α) (3)
Then
Similarly, the y-direction coordinate y of the intersection point of the light rays after n reflectionsn
Converting equation (6) to equation (3)
yn＝Bsin(nθ+β) (7)
Wherein (7) is represented by
From the expressions (3) to (9), it can be found that the intersection point (x) after n reflectionsn、yn) With the point of incidence (x)0、y0) Incidence rate (x'0、y′0) Correlated by d, f. Normally the spots are distributed elliptically, but under certain conditions the spots will be distributed circularly on a concave mirror, i.e. the spots will be distributed circularly on a concave mirror
A＝B (10)
I.e. in case the equations (12) and (13) are fulfilled, the spots will be arranged in a circle on the concave mirror.
Thus, the concave mirrors are selected, i.e. the spacing f is determined, and the point of incidence (x)0，y0) When the light source is fixed, the light incident angle (x ') required for the light spots to be arranged in a circle on the reflector is clear from the expressions (12) and (13)'0、y′0) Only in relation to the distance d between the two concave mirrors, that is, when the distance d is constant, the light is incident at a specific angle, and the light spots are arranged into a circle on the concave mirrors.
Selecting a concave mirror with a focal length of 100mm, setting the mirror spacing to 170mm, and calculating the incident direction as the light incident point at (1, 12.4): x'0＝0.06723，y′0-0.06802. FIG. 7 shows an incident direction of x'0＝0.06723，y′0Fig. 7 shows the spot distribution on the B mirror at-0.06802, and when the incident light is at a specific angle, the spots are arranged on the mirror in a circle, and the specific position of each spot can be determined according to equation (1).
(2) Spot size calculation
If the size of the reflected light spot is known, the position of the reflected light spot is combined, whether the adjacent light spots on the reflector are overlapped or not can be determined, and if the adjacent light spots are overlapped, light spot interference occurs, so that the detection signal is deviated. Meanwhile, by knowing the size of the light spot, whether light leaks in the transmission process can be better judged, for example, the central point of the light has overflowed from the incident hole but the whole light spot is not completely emitted, or the edge light of the light spot has overflowed from the incident hole and the center of the light spot is still reflected, so that errors can be caused in the detection result. Under the condition that the size of each light spot of the light spots on the reflector is known, the arrangement compactness of the light spots on the reflector can be adjusted, and proper incident holes and emergent holes are selected to avoid light spot interference and light leakage, so that the detection error is reduced. As shown in the figure, under certain conditions, the arrangement of the light spots on the concave mirror is obtained, and the total reflection times are respectively 58 times and 118 times. In fig. 8 (a), light is incident from the incident hole, and by observing the distribution of the spots, it can be seen that no overlap occurs between the spots, but part of the light leaks from the incident hole in the 2 nd spot. In fig. 8 (b), it can be seen that the light spots overlap with each other, and it is obvious that the phenomenon of overlapping of the light spots easily occurs when the number of reflections is large. In both cases, errors occur in the final detection result, and related parameters need to be reset, so that the situations of light spot overlapping and light leakage are avoided.
In practical cases, since the incident light is a bundle of incident light, i.e. a plurality of incident light beams in the same directionThe light beams are gathered and the cross sections of the light beams are shaped into circles, so that light rays at the edges of the light beams with a certain divergence angle can be traced, and the tracing of the light beams is realized. When incident light is continuously reflected between the two mirrors, the cross section shape of the light beam can be continuously changed due to the convergence effect of the spherical mirrors, and finally, the sizes of all reflected light spots on the mirrors are different, and the radius of each reflected light spot is changed according to a certain rule. In the z-axis direction, we assume that the contour lines of the incident light rays are L1 and L2, and the incident position coordinates of the two lines in the x-axis direction are x01，x02The slopes are x'01，x′02Then the diameter of the light spot after n reflections is:
RL＝|xn1-xn2|＝|A1sin(nθ+α1)-A2sin（nθ+α2)| (14)
the same applies to the y-direction as to the x-direction.
As shown in fig. 9 (a), we apply this theory to calculate the size and position distribution of the light spots on the reflector when the number of reflections is 30, and the light spots are equally spaced on the concentric circle of the incident hole. According to the same parameters, the light is guided into simulation software to perform ray tracing, and the light intensity analysis is performed on the reflecting surface of the reflector, as shown in fig. 9 (b). It can be seen that the speckle distribution pattern obtained by this theory is substantially consistent with the pattern obtained in the simulation software, so we can calculate the speckle size.
(3) Number of reflections calculation
According to the formula (2), the included angle θ between two adjacent light spots is determined by the mirror pitch d and the mirror focal length f.
Herriott et al teach if the light satisfies the following equation:
nθ＝2μπ (15)
the light ray will pass through the incident point again after n reflections (x)0，y0)＝(xn，yn) In the formula [ theta ]
The number of reflections n increases from 1 in steps of 2, the integer μ increases in steps of 1, and μ represents the complete number of turns of the reflection point around the mirror in steps of the angle θ. If a reflection number n is given, under the condition of a certain curvature radius R, a plurality of groups of solutions simultaneously satisfy the expressions (15) and (16), the reflection modes corresponding to each group of solutions are slightly different, and variables k and p are introduced to describe different reflection modes. To avoid confusion, the solution is expressed using equation (17) and each particular solution in the solution is expressed by { n, μ, k, p }:
n＝2pμ+k (17)
wherein k is ± 2, ± 4, ± 6.
As can be seen from the expressions (14) to (16), the number of reflections n is a function of d, k, p, i.e.
Fig. 10 is a graph (f is 100mm) of the reflection number n and the mirror pitch d provided in the embodiment of the present application, and as shown in fig. 10, a redundancy solution has been excluded, where n is 2p μ + k, k is ± 4, ± 6, ± 8, ± 10, and the number of turns μ in the formula is strictly limited, and when k is ± 4, ± 6, ± 8, ± 10, μ cannot be evenly divided by 2,3, 2, 5, respectively, and when k is ± 2, μ is not limited.
When the incident point and the exit point are the same, the number of turns μ and the number of reflections n correspond to each other when p is 2 and k is-2, as shown in table 1.
TABLE 1 number of turns and number of reflections
The integer mu in the table is the complete number of reflection points on the concave mirror before the beam leaves the cavity, and we have found that for a solution cluster of n 4 mu-2, the number of reflections n (even) achieved is not continuous over an even number when the number of turns mu is incremented by 1, and if mu can take the value 1.5,2.5 …, the number of reflections will be continuous over an even number, thus achieving any number of reflections in a solution cluster of n 4 mu-2. For example, to achieve a value of μ of 1.5, i.e. a complete trajectory of the light beam in the cavity, leaving the reflective cavity midway along the second trajectory, we can control the position of the exit point to achieve the purpose of changing the number of reflections, since we can determine the specific position of each reflection point. Similarly for all solutions, when p is 1,2,3,4 …, we only take k to ± 2, and by controlling the position of the exit point so that the light beam leaves the reflecting pool at the corresponding number of reflections, the graph of the number of reflections n versus the mirror spacing d will change as shown in fig. 11.
The mirror spacing d can be varied continuously, and the number of reflections n can only be integers, for example, d is 170mm, and the number of reflections n is 20.86 in a cluster solution where n is 4p +2, where we do this by rounding down to n is 20. As can be seen from fig. 9, at a certain focal length, the number of reflections n is only related to the mirror spacing d, and we realize that the number of reflections is continuous at n ═ 2p ± 2(n is an integer) by controlling the position of the exit point, we can obtain different numbers of reflections by changing the mirror spacing d, and the corresponding relationship between them is already clear.
(4) Optical path calculation
a)d>R
In order to calculate the optical path more accurately, the two reflectors and light rays are subjected to geometric analysis in a three-dimensional form, wherein Q is a curvature center, P is a projection point of a normal on a distribution surface, d is a central distance between the two reflectors, t is a distance from the curvature center to a light spot distribution surface of a far reflector, v is a distance from the normal to an axis in a projection manner, s is a distance from the curvature center to a light spot distribution surface of a near reflector, and an included angle between the normal and the axis is formed.
Distance t from center of curvature to distribution surface
Normal line forms an angle with the axis
Center of curvature to another distribution surface s
s＝d+t-2R (21)
Normal projection to axis distance v
v＝s·tan() (22)
Distance w from center of curvature Q to projection point P
Then, when d > R, the single optical path OD
b)d<R
Distance t from center of curvature to distribution surface
Normal line forms an angle with the axis
Center of curvature to another distribution surface s
s＝2R-d-t (27)
Normal projection to axis distance v
v＝s·tan() (28)
Distance w from center of curvature Q to projection point P
Then, when d < R, the single optical path OD
When 0< d < R, as shown in the formulae (19) to (30)
By equation (31), it can be found that OD is a function of d, R, and that OD is a function of d when the concave mirror is selected and the entrance aperture is defined.
Then the total optical length L
L＝n·OD (32)
Since the number of reflections n is only related to d in a certain reflection mode, and the single optical path OD is a function of d, it can be known that the optical path L is a function of d:
wherein A ═ R2+r2，B＝t-2R。
The following further description is made, by way of example, in accordance with the above methods and principles:
(1) multiple reflection cell parameter design
TABLE 2 multiple reflection cell parameter design
The light source type is selected to be a gaussian light source.
TABLE 3 light source parameter design
(2) Determining mirror spacing and exit point position
After the setting of the parameters of the reflecting mirror system is completed, assuming that we need the optical length L to be 19.82m, a graph of the relationship between the optical length L and the mirror pitch d can be obtained according to equation (33), as shown in fig. 12.
When the optical length L is 19.82m, it can be found that a plurality of d can satisfy the optical length, and obviously, the smaller d is, the more reflection times are required, and the larger d is, the less reflection times are required. Therefore d is chosen to be 193.9mm, 206.5mm and 398.3 mm. As can be seen from fig. 11, the number of reflections n is 102 for d-193.9 mm, 96 for d-206.5 mm, and 48 for d-398.3 mm.
Since the position of the incident point (x) is known0、y0) And a focal length f, and when d is 193.9mm, the direction of the incident light can be found from equations (12) and (13) as: x'0＝0.02251，y′0-0.1419; when d is 206.5mm, the direction of incident light is: x'0＝0.01744，y′0-0.1381; when d is 398.3mm, the direction of incident light is: x'0＝-0.05488，y′0-0.08372. According to the formulas (1), (6) and (14), the position of each light spot on the reflector and the size of each light spot under three conditions can be obtained, as shown in tables 4 to 6, even light spots are distributed on the mirror A, and odd light spots are distributed on the mirror B.
TABLE 4 distribution of spots at 193.9mm
TABLE 5 Spot distribution at d-206.5 mm
TABLE 6 Spot distribution at d-398.3 mm
And a proper emergent hole can be arranged according to the specific position and size of the light spot to ensure that the reflection times meet the requirements. For example, if the required number of reflections is 102, an exit aperture with an aperture of 1mm is provided on the concave mirror A (1.8461, 19.9995) placed in the x-y plane.
(3) Design results and analysis
In simulation software, a Herriott type reflecting pool model is built by taking a spherical reflector as a concave reflecting mirror of a multiple reflecting pool, light sources are arranged according to laser light sources of a semiconductor laser, light paths are simulated, and under the condition that d is different, light spot distribution diagrams are shown in figures 13-15.
As can be seen from fig. 13 to 15, in the case of different mirror pitches d, the light spots can be arranged in a circular shape on the mirrors by setting the corresponding incident angles, and the required number of reflections n can be achieved by setting the appropriate positions of the exit holes. In fig. 13, it can be seen that although the number of reflections can meet the requirement, there is a spot overlapping phenomenon, which causes spot interference. As can be seen from fig. 14 and 15, there is no overlapping and light leakage phenomenon between adjacent light spots, but d is 398.4mm, compared with d 206.5mm, the absorption cell has a larger volume, which is not beneficial to miniaturization and sensitivity improvement, so d is 206.5mm as the best choice. At this time, the OPL was 19.823m as seen from the simulation software optical path analysis. That is, when f is 100mm, d is 206.5mm, and the optical path length L is realized with the number of reflections being 96, the error | Δ L |, between the optical path length L and the actual optical path length OPL is 3mm, which is 0.015% of the optical path length L being 19.82 m. According to the design method, Herriott type multiple reflection times of a required optical path can be conveniently designed.
The embodiments in this specification are described in a progressive manner. The same and similar parts among the various embodiments can be mutually referred, and each embodiment focuses on the differences from the other embodiments.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It should be noted that, unless otherwise specified and limited, the terms "connected" and "connected" are to be interpreted broadly, and may be, for example, mechanically or electrically connected, or may be communicated between two elements, directly or indirectly through an intermediate medium, and specific meanings of the terms may be understood by those skilled in the relevant art according to specific situations. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a circuit structure, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, the presence of an element identified by the phrase "comprising an … …" does not exclude the presence of additional like elements in the article or device comprising the element. In addition, as used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (10)
1. A variable optical path multiple reflection cell, said cell comprising: the device comprises an absorption air chamber (1), an optical window (2) and a reflector (3);
the absorption gas chamber (1) comprises a quartz cavity (11), a stepped spiral cavity (12) and a differential spiral cavity (13) which are sequentially connected, the quartz cavity (11) is fixedly connected with the stepped spiral cavity (12) through an intermediate plate (4), and the stepped spiral cavity (12) is in threaded connection with the differential spiral cavity (13);
an air inlet (5) and an air outlet (6) are arranged on the absorption air chamber (1);
the stepped spiral cavity (12) is formed by a stepped spiral structure (120), and the stepped spiral structure (120) comprises a lower stepped spiral structure (121), an upper stepped spiral structure (123) and a middle stepped spiral structure (122) which are sequentially connected;
the differential spiral cavity (13) is composed of a differential spiral structure (130), and the differential spiral structure (130) comprises an upper differential spiral structure (131), a middle differential spiral structure (132) and a lower differential spiral structure (133) which are sequentially connected;
the reflector (3) comprises two coaxial concave reflectors with the same focal length and is fixed at the front end and the rear end of the absorption air chamber (1);
a reflector (3) at the front end of the absorption air chamber (1) is provided with an entry hole (7);
the optical window (2) is arranged at the front end of the front end reflector (3) of the absorption air chamber (1).
2. The variable optical path multiple reflection cell according to claim 1, wherein the intermediate plate (4), the stepped spiral cavity (12), and the differential spiral cavity (13) are made of aluminum material and have inner cavity surfaces subjected to blackening treatment.
3. The variable optical path multiple reflection cell according to claim 1, wherein the aperture size of the entrance hole (7) is 1-3 mm.
4. The variable optical path multiple reflection cell according to claim 1, characterized in that the mirror (3) is made of quartz material.
5. The variable optical path multiple reflection cell according to claim 4, wherein the reflecting surface of the mirror (3) is plated with gold.
6. The variable optical path multiple reflection cell of claim 5, wherein said gold film is coated with SiO2And (3) a layer.
7. The variable optical path multiple reflection cell according to claim 1, wherein the junction of the quartz cavity (11) with the intermediate plate (4) and the stepped spiral cavity (12) is sealed with an O-ring.
8. The variable optical path multiple reflection cell according to claim 1, wherein the entrance hole (7) is disposed near an edge of the mirror (3).
9. The optical path variable multiple reflection cell according to claim 1, wherein a laser adjusting frame (8) is arranged above the reflection cell, the laser adjusting frame (8) is used for installing and adjusting a laser, a plane mirror support (9) is further arranged at the front end of the reflection cell, the plane mirror support (9) is used for installing a plane mirror, and the plane mirror is used for reflecting laser emitted by the laser into the optical window (2).
10. A method for adjusting an optical length of a variable optical length multi-reflecting cell, which comprises using the variable optical length multi-reflecting cell according to any one of claims 1 to 9, the method comprising:
obtaining a reflector distance according to a preset optical path, wherein the optical path and the reflector distance satisfy the following relation:
in the formula: l is an optical path, P is a positive integer, d is a reflector spacing, d ranges from 0 to 4f (f is a focal length), R is a reflector curvature radius, R is a distance from the center of an incident hole to an optical axis, and A is equal to R2+r2，B＝t-2R；
Determining the reflection times according to the reflector spacing, wherein the relationship between the reflector spacing and the reflection times is as follows:
in the formula: n reflector spacing is P and is a positive integer, d is reflector spacing, the value range of d is 0-4 f (f is focal length), and R is reflector curvature radius;
determining a direction of incident light according to the mirror spacing, wherein a relationship that is satisfied between the mirror spacing and the direction of the incident light is:
in the formula: (x)0，y0) Is the position coordinate of an incident point, f is a focal length, d is a reflector spacing, and the value range of d is 0-4 f, (x'0，y’0) Is the incident angle of the light;
determining the position of each light spot on the reflector according to the direction of the incident light and the reflector spacing, wherein the relationship satisfied by the direction of the incident light, the reflector spacing and the position of each light spot on the reflector is as follows:
in the formula: (x)n，yn) For each spot position coordinate on the mirror, (x)0，y0) Is the position coordinate of an incident point, f is a focal length, d is a reflector spacing, and the value range of d is 0-4 f, (x'0，y’0) Is the angle of incidence of the light, theta isThe included angle between two adjacent light spots satisfies
Determining the position of an exit hole according to the reflection times;
an emergent hole is formed in the reflector of the reflecting pool according to the position of the emergent hole;
and adjusting the step spiral structure and the differential spiral structure of the reflecting pool according to the distance between the reflecting mirrors to obtain the optical path.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113008838A (en) * | 2021-03-17 | 2021-06-22 | 华北电力大学 | Optical cavity, heating cavity, measuring device and liquid medium transmission spectrum measuring system |
| CN113189012A (en) * | 2021-04-07 | 2021-07-30 | 山西大学 | Enhanced photoacoustic sensing device and method |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1397657A1 (en) * | 1986-02-19 | 1988-05-23 | Специальное Конструкторское Бюро Института Радиотехники И Электроники Ан Ссср | Differential screw-type mechanism |
| US20060232772A1 (en) * | 2004-07-21 | 2006-10-19 | Southwest Sciences Incorporated | Dense pattern optical multipass cell |
| US7800751B1 (en) * | 2006-02-27 | 2010-09-21 | Southwest Sciences Incorporated | Dense pattern multiple pass cells |
| CN102879898A (en) * | 2012-09-29 | 2013-01-16 | 太原科技大学 | Automatic tunable system with multiple optical paths |
| CN103884677A (en) * | 2012-12-19 | 2014-06-25 | 北京大方科技有限责任公司 | Gas analyzer sample gas chamber apparatus with characteristic of easy optical path adjustment |
| CN104033863A (en) * | 2014-06-23 | 2014-09-10 | 哈尔滨工业大学 | Differential screw height-adjustable LED (light emitting diode) lamp base and T-shaped calibrating form board using same |
| CN105548014A (en) * | 2015-12-29 | 2016-05-04 | 中国科学院合肥物质科学研究院 | Optical absorption device with adjustable double absorption optical paths |
| CN110715909A (en) * | 2019-10-30 | 2020-01-21 | 山东大学 | Multi-channel multi-reflection gas detection device |
-
2020
- 2020-08-27 CN CN202010878267.6A patent/CN111982817B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1397657A1 (en) * | 1986-02-19 | 1988-05-23 | Специальное Конструкторское Бюро Института Радиотехники И Электроники Ан Ссср | Differential screw-type mechanism |
| US20060232772A1 (en) * | 2004-07-21 | 2006-10-19 | Southwest Sciences Incorporated | Dense pattern optical multipass cell |
| US7800751B1 (en) * | 2006-02-27 | 2010-09-21 | Southwest Sciences Incorporated | Dense pattern multiple pass cells |
| CN102879898A (en) * | 2012-09-29 | 2013-01-16 | 太原科技大学 | Automatic tunable system with multiple optical paths |
| CN103884677A (en) * | 2012-12-19 | 2014-06-25 | 北京大方科技有限责任公司 | Gas analyzer sample gas chamber apparatus with characteristic of easy optical path adjustment |
| CN104033863A (en) * | 2014-06-23 | 2014-09-10 | 哈尔滨工业大学 | Differential screw height-adjustable LED (light emitting diode) lamp base and T-shaped calibrating form board using same |
| CN105548014A (en) * | 2015-12-29 | 2016-05-04 | 中国科学院合肥物质科学研究院 | Optical absorption device with adjustable double absorption optical paths |
| CN110715909A (en) * | 2019-10-30 | 2020-01-21 | 山东大学 | Multi-channel multi-reflection gas detection device |
Non-Patent Citations (2)
| Title |
|---|
| J. ALTMANN, R. BAUMGART, C. WEITKAMP: "Two-mirror multipass absorption cell" * |
| 戴树煌: "长光程大气模拟池中微位移机构设计及精度分析" * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113008838A (en) * | 2021-03-17 | 2021-06-22 | 华北电力大学 | Optical cavity, heating cavity, measuring device and liquid medium transmission spectrum measuring system |
| CN113189012A (en) * | 2021-04-07 | 2021-07-30 | 山西大学 | Enhanced photoacoustic sensing device and method |
| CN113189012B (en) * | 2021-04-07 | 2022-12-30 | 山西大学 | Enhanced photoacoustic sensing device and method |
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|---|---|
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