Interferometer based on double-movable-arm rotation and working method

Abstract

A beam splitter is used for receiving a collimated light source and emitting a reflected light beam and a transmitted light beam, and the reflected light beam and the transmitted light beam return to the beam splitter to be recombined after being reflected by a plane mirror and are received by a detector through an imaging lens; wherein the plane mirrors comprise a first mirror and a third mirror which are parallel to each other and form a pair, and a second mirror and a fourth mirror which are parallel to each other and form a pair, and the two pairs of mirrors are respectively fixed on corresponding movable arms and are driven by the respective movable arms to rotate around a rotating shaft; the rotating shaft is located at the axisymmetric center of the second reflector and the fourth reflector. Compared with a Michelson interferometer, the interferometer has the advantages that the problem caused by inclination of the moving mirror is greatly reduced when the interferometer is applied to the Fourier transform spectrometer, and meanwhile, a large optical path difference is obtained in a small rotation angle.

Description

Technical Field

[0001] The present invention relates to the technical field of interferometers, and specifically to an interferometer based on the rotation of a double moving arm and a working method thereof. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] A spectrometer is an instrument used to measure light or other electromagnetic radiation, capable of analyzing spectral components, and can be divided into filter spectrometers, diffraction grating spectrometers, Fourier transform spectrometers, etc. Among them, the Fourier transform spectrometer has advantages such as multi-channel, large radiation throughput, and low stray light. By generating interference fringes, the spectral information of the target is obtained using the Fourier transform relationship between the interferogram and the spectrum.

[0004] The Fourier transform spectrometer can be divided into a time-modulated spectrometer and a space-modulated spectrometer. Among them, the time-modulated Fourier transform spectrometer takes the Michelson interferometer as the core component, and its technical principle is as follows: The incident light beam is split into two beams by a beam splitter: a reflected beam and a transmitted beam; the reflected beam is reflected by a stationary mirror and transmitted by the beam splitter to reach a focusing mirror; the transmitted beam is reflected by a moving mirror and reflected by the beam splitter to reach the focusing mirror; the two beams of light are focused and imaged on a detector, and interference fringes are formed, and then the spectral information is obtained using the Fourier transform.

[0005] The moving mirror of the Michelson interferometer is prone to tilting during the movement. Usually, the tilt angle of the moving mirror of the interferometer should be less than λ / (8d), where λ is the wavelength and d is the aperture of the moving mirror, and it is difficult for the general interferometer movement accuracy to meet this requirement. Summary of the Invention

[0006] In order to solve the technical problems existing in the above background technique, the present invention provides an interferometer based on the rotation of a double moving arm and a working method thereof. Compared with the Michelson interferometer, in the application of the Fourier transform spectrometer, this interferometer greatly reduces the problems caused by the tilting of the moving mirror, and at the same time obtains a large optical path difference at a small rotation angle.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention provides an interferometer based on the rotation of a double moving arm, including:

[0009] A beam splitter for receiving the collimated light source and emitting a reflected beam and a transmitted beam. After the reflected beam and the transmitted beam are reflected by a plane mirror, they return to the beam splitter for recombination and are received by a detector through an imaging lens;

[0010] The plane mirror includes a first mirror and a third mirror that are parallel to each other and form a pair, and a second mirror and a fourth mirror that are parallel to each other and form a pair. The two pairs of mirrors are respectively fixed on corresponding moving arms and are driven by their respective moving arms to rotate around a rotation axis, and the rotation axis is located at the axisymmetric center of the second mirror and the fourth mirror.

[0011] As a further implementation, there are at least two sets of plane mirrors. One set of plane mirrors is arranged in the optical path of the first mirror and the second mirror, and the other set of plane mirrors is arranged in the optical path of the third mirror and the fourth mirror.

[0012] As a further implementation, after the reflected light beam passes through the first mirror and the second mirror and reaches the plane mirror, it is reflected back to the beam splitter again.

[0013] As a further implementation, after the transmitted light beam passes through the third mirror and the fourth mirror and reaches another plane mirror, it is reflected back to the beam splitter again.

[0014] As a further implementation, the beam splitter is at a 45° angle to the horizontal plane.

[0015] As a further implementation, when the interferometer is in the initial state, all the mirrors are at a 45° angle to the horizontal plane.

[0016] As a further implementation, a collimating lens is provided between the light source and the beam splitter for collimating the light beam before it enters the beam splitter.

[0017] As a further implementation, during the rotation of the moving arm around the rotation axis, there is a set angle range that allows rotation.

[0018] As a further implementation, the first mirror, the second mirror, the third mirror, and the fourth mirror are all square.

[0019] The second aspect of the present invention provides a working method of an interferometer based on the rotation of a double moving arm, including the following steps:

[0020] The light source is collimated and emits a reflected light beam and a transmitted light beam through the beam splitter;

[0021] After the reflected light beam passes through the first mirror and the second mirror and reaches the plane mirror, it is reflected back to the beam splitter again;

[0022] After the transmitted light beam passes through the third mirror and the fourth mirror and reaches another plane mirror, it is reflected back to the beam splitter again;

[0023] The light beam reflected back to the beam splitter is recombined and enters the detector through the imaging lens.

[0024] Compared with the prior art, the above one or more technical solutions have the following beneficial effects:

[0025] 1. Two pairs of mirrors are respectively fixed on the corresponding moving arms, and each mirror is driven by the moving arm to rotate. Since the mirror can only be driven to rotate by the moving arm, the mechanical structure can forcibly suppress the tilt components in other directions, reduce the influence of the moving mirror tilt on the interferometer, and improve the accuracy of the interferometer.

[0026] 2. The first mirror M1 and the third mirror M3 are parallel to each other, and at the same time, the second mirror M2 and the fourth mirror M4 are parallel to each other. Therefore, no matter how the moving arm rotates, the round-trip path of the incident light beam passing through the beam splitter, M1, M3, and the plane mirror will not shift. Therefore, there will be a large beam intersection range between the incident light beam and the reflected light beam on the beam splitter, and thus a high modulation depth can be maintained.

[0027] 3. When the double moving arms rotate, due to the change in the position of each mirror on the moving arm, a 2-fold optical path difference will be generated in the path of the light beam traveling back and forth between the beam splitter and the plane mirror. And there are 4 mirrors in total on the double moving arms, thus generating an 8-fold optical path difference, that is, a small rotation angle generates a large optical path difference, which is suitable for high-resolution spectrometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0029] Figure 1 is a schematic diagram of the principle of a rotational motion interferometer provided by one or more embodiments of the present invention;

[0030] Figure 2 is a partial optical path schematic diagram of a rotational motion interferometer provided by one or more embodiments of the present invention;

[0031] Figure 3 is a schematic diagram of the relationship between the rotation angle of the moving arm and |E’P’| provided by one or more embodiments of the present invention;

[0032] Figure 4 is a schematic diagram of the relationship between the rotation angle of the moving arm and the optical path difference provided by one or more embodiments of the present invention;

[0033] Figure 5 is a partial optical path schematic diagram on a single moving arm provided by one or more embodiments of the present invention;

[0034] Figure 6 is a schematic diagram of the relationship between the rotation angle of the moving arm and |QM’| provided by one or more embodiments of the present invention;

[0035] Figure 7 is a schematic diagram of the overall structural principle of a spectrometer provided by one or more embodiments of the present invention. Detailed implementation mode

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further descriptions of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0038] It should be noted that the terms herein are only for describing specific implementation modes and are not intended to limit the exemplary implementation modes according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0039] A Michelson interferometer is an instrument that uses the interference phenomenon of light for measurement. Generally, it is the core component of a Fourier transform spectrometer. The basic technical principle is as follows: The incident light is split into two beams by a beam splitter, and after being reflected by the mirrors respectively, they are recombined to produce interference fringes. By moving one of the mirrors, the optical path difference is changed, and the interference fringes will change accordingly, thus obtaining an interferogram. Subsequently, the interferogram is converted into a spectrogram through Fourier transform.

[0040] As introduced in the background technology, the moving mirror of a Michelson interferometer is prone to tilt during movement. Generally, the tilt angle of the moving mirror of an interferometer should be less than λ / (8d), where λ is the wavelength and d is the aperture of the moving mirror. However, it is difficult for the general interferometer movement accuracy to meet this requirement.

[0041] Therefore, the following embodiments provide an interferometer based on the rotation of a double moving arm and its working method. Compared with the Michelson interferometer, in the application of a Fourier transform spectrometer, this interferometer greatly reduces the problems caused by the tilt of the moving mirror and at the same time obtains a large optical path difference at a small rotation angle.

[0042] Embodiment 1:

[0043] The simplified optical path diagram of the interferometer based on the rotation of a double moving arm is as Figure 1 shown. The optical path consists of a collimation system, a beam splitter (Beam spliter) O, two pairs of plane mirrors (A, A', B, B'), two fixed plane mirrors C and C' (corresponding to Fixedmirror1 and Fixed mirror2), and a detector.

[0044] The collimation system consists of a collimating lens (objective lens) with a focal length of f and an imaging lens. Two pairs of plane mirrors (A, A', B, B') are respectively fixed on two moving arms. Each pair of plane mirrors is parallel to each other in the installation position and is driven by the moving arm to rotate around the rotation axis R. Since the rotating mirrors are fixed on the double moving arms, during the movement, it is the moving arm that rotates to drive the mirrors to rotate, and the mirrors themselves are fixed on the moving arms. Therefore, A and B remain parallel during rotation, and A' and B' remain parallel, without the problem of the moving mirror tilting that occurs in traditional interferometers. Among them, the moving arm rotates around the rotation axis R, and the rotation axis is located at the axisymmetric center of the plane mirrors B and B'.

[0045] The working principle of this interferometer is as follows: The light beam emits from the light source. After being collimated by the collimating lens (objective lens), the light beam is vertically incident on the beam splitter O. The beam splitter O divides the light beam into a reflected beam and a transmitted beam. The reflected beam and the transmitted beam respectively pass through the mirrors on the moving arms and are reflected to the fixed plane mirrors, and then are reflected back to the beam splitter O through the plane mirrors and the mirrors, and are recombined at the beam splitter and enter the imaging lens. Finally, they are received by the detector CCD.

[0046] In this embodiment, the plane mirrors A and A' are named the first mirror and the third mirror, and the plane mirrors B and B' are named the second mirror and the fourth mirror. The first mirror A and the third mirror A' are parallel to each other and form a pair, and the second mirror B and the fourth mirror B' are parallel to each other and form a pair. The two pairs of plane mirrors (A, A', B, B') are respectively fixed on two moving arms and are driven by their respective moving arms to rotate around the rotation axis R.

[0047] Therefore, the above technical principle is as follows:

[0048] After being collimated by the collimating lens, the light beam is vertically incident on the beam splitter O, and the beam splitter O divides the light beam into a reflected beam and a transmitted beam;

[0049] The reflected beam reaches the fixed plane mirror C after passing through the first mirror A and the second mirror B, and then is reflected back to the beam splitter O;

[0050] The transmitted beam reaches the fixed plane mirror C' after passing through the third mirror A' and the fourth mirror B', and then is reflected back to the beam splitter O;

[0051] The two beams of light reflected back to the beam splitter O are recombined and enter the imaging lens, and finally are received by the detector CCD.

[0052] The overall optical path design process is as follows:

[0053] 1. Collimation System Design

[0054] In order to ensure low aberration while keeping the size of the optical system within the required range, the lens material and its focal length of the collimation system are analyzed. To improve the signal-to-noise ratio, the input light source is designed to first pass through a concave lens for focusing and then output to the collimating lens. The wavenumber of the spectral range is 350 - 7500 cm-1, the corresponding wavelength is 1.33 - 28.57 μm, and the corresponding spectral region is the infrared spectral region. Therefore, Si is selected as the lens material of the interferometer, and its transmittance is about 80% - 90%.

[0055] If the focal length of the lens is too long, it will cause the size of the optical system to be too large. If the focal length is too short, it will cause too large aberration. And the design target size of the interferometer is length × width less than 450 × 450 mm. To ensure meeting the size requirements, the lens focal length is selected as 175 mm, which is less than the minimum design size of the interferometer, 450 mm, meeting the design requirements. Usually, its lens focal length is much larger than the lens thickness, and the lens focal length formula is

[0056]

[0057] where f represents the focal length, n represents the lens refractive index, and R represents the lens curvature radius. To ensure a smaller divergence angle, the focal length selected in this embodiment is 175 mm, then the corresponding lens curvature radius is about 35 mm, and the thickness is selected as 2.66 mm. According to the simulation, when the focal length is 175 mm, the focusing effect is poor. When it is changed to 143.773 mm, the focusing effect is good.

[0058] 2. Rotatable Angle Analysis

[0059] Figure 2 Shows a partial optical path diagram of the rotating interferometer. The first mirror A is denoted as EN, the second mirror B is denoted as IL, EN and IL are parallel to each other to form a pair and are fixed on the moving arm 1. The third mirror A' and the fourth mirror B' are parallel to each other to form a pair and are fixed on the moving arm 2. The beam spliter is denoted as D'F'.

[0060] where |E'F'| is the reflected light beam generated by the moving arm 1 on the beam splitter, |D'P'| is the transmitted light beam generated by the moving arm 2 on the beam splitter, and the range of |E'P'| on the beam splitter is the intersection part of the two light beams. The interference pattern is generated in the intersection part of the two light beams. From Figure 2 it can be seen that as the moving arm rotates, the intersection part of the two light beams will gradually decrease. Therefore, it is necessary to determine the rotation range of the moving arm.

[0061] The variables in the optical path are defined as follows: Assume the distance between the mirror B on the moving arm 1 and the rotation axis is The diameter of the beam splitter, the diameter of the mirror, and the installation distance between the mirrors are 2d, and the rotation angle of the moving arm around the rotation axis R is α.

[0062] From Figure 2 it can be seen that when the value of |E’P’| is 0, the two light beams have no intersection part and cannot form an interference pattern. Therefore, it is necessary to calculate |E’P’|.

[0063] From Figure 2 it is known that |E’P’| is the diameter of the beam splitter minus |E’D’| and |P’F’|. Since the moving arm of the interferometer is an axisymmetric structure, |D’E’| is equal to |P’F’|.

[0064] To sum up, |E'P'| = |D'F'| - 2|D'E'|. The projection of |D’E’| in the horizontal direction is |RHi| - |RH|, where |RHi| is the |RH| when the interferometer is at the zero optical path difference position. |RH| can be regarded as the sum of |MR|, |IP|, and |GI|. Among them, from Figure 2 the geometric relationship, it can be known that

[0065]

[0066] |IP| = |IL|·sinα = d·sinα (3)

[0067] Since the mirrors A and B are at an angle of 45° with the horizontal when the interferometer is at the zero optical path difference position, ∠EIL = 135°. According to Figure 2 it is known that ∠LIP = 90° - α, so ∠EIG = α - 45°. Thus, it can be known that |GI| is:

[0068] |GI| = |EI|cos(α - 45°) = 2dcos(α - 45°) (4)

[0069] The expression of |RH| can be obtained from |MR|, |IP|, and |GI|:

[0070]

[0071] When the interferometer is at the zero optical path difference, α is equal to 45°. Combining with formula (5), |RHi| is:

[0072]

[0073] Then it can be calculated that |D’E’| is:

[0074]

[0075] Therefore, |E’P’| is:

[0076]

[0077] When the interferometer is at the zero optical path difference position, its rotation angle is 45°. The relationship between the rotation angle of the movable arm and |E’P’| is as Figure 3 shown.

[0078] It can be found that when α≈76°, the transmitted beam and the reflected beam cannot intersect, that is, |E’P’| = 0, resulting in the interferometer being unable to form an interference pattern.

[0079] That is, the two movable arms are coupled together and rotated synchronously, and the rotation axis corresponds to Figure 1 the “Rotation axis” shown, then the range of the rotatable angle satisfies the following formula:

[0080]

[0081] In this embodiment, since the included angle of the movable arms in the initial optical path is 45°, the range of the rotatable angle of the movable arms is 14° to 76°.

[0082] 3. Optical path difference analysis

[0083] Since the resolution of the spectrometer needs to reach 0.045 cm-1, from Equation (2), it can be obtained that the maximum optical path difference is at least 112 mm. The maximum optical path difference generated by the single mirror is 1 / 4 of the maximum optical path difference of the entire optical system, that is, 28 mm. The relationship between the rotation angle α of the movable arm and the optical path difference OPD is as Figure 4 shown.

[0084] From Figure 2 and Figure 4 it can be seen that when the movable arm of the interferometer rotates, the optical path difference generated by the single mirror mainly occurs on |EH|. |EH| can be regarded as the sum of |PM| and |EG|. Among them, |PM| = |LM| - |LP|. From the geometric relationship, |LM| = |LR|·sin(α), |LP| = |IL|·cos(α). Then |PM| is:

[0085]

[0086] Since ∠EIG = α - 45°, then |EG| is:

[0087] |EG| = 2d·sin(α - 45°) (10)

[0088] Then the optical path difference |EH| generated by the single mirror is:

[0089] |EH| = |EG| + |PM| = 4d·sin(α - 45°) (11)

[0090] Since the lens radius of the collimation system is 35 mm, to ensure maximum reception of the light beam, the diameter d of the mirror is also selected as 35 mm. To meet the interference requirements and combined with formula (11), the maximum rotation angle is calculated to be approximately 57°. Combining with the previous text, this rotation angle is less than 76°, meeting the interference requirements. Therefore, the rotation angle range of the moving arm is selected as 33° to 57°.

[0091] When the rotation angle range of the moving arm is selected as 33° to 57°, the relationship diagram between the rotation angle of the moving arm and the optical path difference (4|EH|) generated by the interferometer is as Figure 4 shown. It can be found that the calibration curve between the rotation angle of the moving arm and the optical path difference basically coincides with the fitting straight line, and its non-linear error is small, only ±0.1%. The non-linear error δ is:

[0092]

[0093] where ΔY max is the maximum deviation between the calibration curve and the fitting straight line, and Y FS is the full-scale output of the interferometer.

[0094] 4. Overall optical structure design

[0095] During the rotation of the interferometer, it is also necessary to consider whether the mirror on the moving arm will block the light beam during the rotation of the moving arm. The range where the light beam is reflected onto the beam splitter must exceed half of the beam splitter, otherwise an interference pattern cannot be formed. The local optical path diagram on the single moving arm is as Figure 5 shown. It can be seen from the figure that when |RM’| = |RQ|, the mirror on the moving arm will block the light beam, thus affecting the interference pattern. Therefore, it is necessary to calculate |RM’| and |RQ|. According to the law of reflection, |II’| = |FN| = |D’E’|, and |MM’| = (|IL| - |II’|) × sinα. Therefore, |RM’| is:

[0096]

[0097] From Figure 5 it can be seen that |RQ| = |RH| - |HQ|. According to the geometric relationship in the figure, it can be known that ∠NEQ' = 90° - α. Therefore, |HQ| = 2d × cos(90° - α). Combining with equation (5), |RQ| can be obtained as:

[0098]

[0099] |QM’| is |RQ| minus |RM’|, and the specific expression is:

[0100]

[0101] The relationship diagram between |QM’| and the boom rotation angle is as follows Figure 6 As shown, it can be found that |QM’| in the designed interferometer cannot be equal to 0. Therefore, the mirror on the boom will not block the light beam.

[0102] Based on the above analysis, it can be found that this rotary interferometer will inevitably reduce its modulation depth during operation. To avoid this situation, the mirrors need to be further improved. Since the hole of the beam splitter is circular, if the shape of the mirror corresponds to that of the beam splitter, a large amount of spectral information will be lost when the interferometer rotates. Therefore, the mirrors used need to be changed to square shape to receive all the light beams emitted by the beam splitter.

[0103] From Figure 3 it can be found that when the rotation angle is 57°, the modulation depth is only 85% of that at the zero optical path difference position. And from Figure 6 it is known that when the rotation angle is 33 - 57°, there is a space of more than 4d for |QM’|. Therefore, the size of the mirror can be lengthened.

[0104] When the rotation angle is 57°, it is at the position where the modulation depth of the interferometer is the smallest. Therefore, only this position is analyzed. mainly because there is no interference in the range of |DE’| on the beam splitter. Therefore, the mirror needs to be extended by this length. According to Equation (9), when the rotation angle is 57°, |DE’| is approximately 3.56d. Therefore, the mirror is extended by 3.57d. At the same time, to avoid the mirrors blocking each other, the mirrors are extended in a specific direction. For example: mirror A is extended in the direction, and mirror B is extended in the direction. It is verified that this extension will not cause the light beam to be blocked. Therefore, to increase the modulation depth, the mirror is changed from circular to square, and the side length is set to 4.57d, that is, 159.95mm.

[0105] Since the input light source is first focused by a concave lens and then output to the collimating lens, and the focal length f of the collimating lens is 175mm, a space of 350mm should be reserved. The design goal of the interferometer is that the size is less than 450×450mm in length×width×depth. To facilitate adjusting the light path focusing effect and meet the design requirements of the interferometer, the overall spectrometer structure is as Figure 7 shown. The distances L from the interferometer to mirror L, from mirror 2 to the plane mirror, and from the collimating system lens to the beam splitter are all selected as 100mm.

[0106] In the structure of the above interferometer, two pairs of mirrors are respectively fixed on the corresponding booms, and the booms drive their respective mirrors to rotate. Since the mirrors can only be rotated by the booms, the mechanical structure can forcibly suppress the tilt components in other directions, reducing the influence of the moving mirror tilt on the interferometer and improving the accuracy of the interferometer.

[0107] The first reflecting mirror M1 and the third reflecting mirror M3 are parallel to each other, and at the same time, the second reflecting mirror M2 and the fourth reflecting mirror M4 are parallel to each other. Therefore, no matter how the moving arm rotates, the round-trip path of the incident light beam through the beam splitter, M1, M3, and the plane mirror can remain unshifted. As a result, there will be a large beam intersection range between the incident light beam and the reflected light beam on the beam splitter, and thus a high modulation depth can be maintained.

[0108] When the double moving arm rotates, the position of each reflecting mirror on the moving arm changes, and a 2-fold optical path difference will be generated in the path of the light beam traveling back and forth between the beam splitter and the plane mirror. Since there are 4 reflecting mirrors on the double moving arm, an 8-fold optical path difference is generated, that is, a small rotation angle generates a large optical path difference, which is suitable for a high-resolution spectrometer.

[0109] Embodiment 2:

[0110] A working method of an interferometer based on the rotation of a double moving arm includes the following steps:

[0111] The light source is collimated and then emits a reflected light beam and a transmitted light beam through a beam splitter;

[0112] The reflected light beam passes through the first reflecting mirror and the second reflecting mirror and reaches the plane mirror, and then is reflected back to the beam splitter;

[0113] The transmitted light beam passes through the third reflecting mirror and the fourth reflecting mirror and reaches another plane mirror, and then is reflected back to the beam splitter;

[0114] The light beam reflected back to the beam splitter is recombined and then enters the detector through an imaging lens.

[0115] The first reflecting mirror M1 and the third reflecting mirror M3 are parallel to each other, and at the same time, the second reflecting mirror M2 and the fourth reflecting mirror M4 are parallel to each other. Therefore, no matter how the moving arm rotates, the round-trip path of the incident light beam through the beam splitter, M1, M3, and the plane mirror can remain unshifted. As a result, there will be a large beam intersection range between the incident light beam and the reflected light beam on the beam splitter, and thus a high modulation depth can be maintained.

[0116] When the double moving arm rotates, the position of each reflecting mirror on the moving arm changes, and a 2-fold optical path difference will be generated in the path of the light beam traveling back and forth between the beam splitter and the plane mirror. Since there are 4 reflecting mirrors on the double moving arm, an 8-fold optical path difference is generated, that is, a small rotation angle generates a large optical path difference, which is suitable for a high-resolution spectrometer.

[0117] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An interferometer based on double arm rotation, characterized in that: include: A beam splitter is used to receive the collimated light source and emit a reflected light beam and a transmitted light beam. After being reflected by a plane reflector, the reflected light beam and the transmitted light beam return to the beam splitter for recombination and are received by a detector through an imaging lens; The plane reflector includes a first reflector and a third reflector which are parallel to each other and form a pair, and a second reflector and a fourth reflector which are parallel to each other and form a pair. The two pairs of reflectors are respectively fixed on corresponding movable arms and driven by their respective movable arms to rotate around a rotation axis, and the rotation axis is located at the axial symmetry center of the second reflector and the fourth reflector.

2. The interferometer based on double arm rotation as claimed in claim 1, characterized in that: At least two groups of plane mirrors are also provided, wherein one group of plane mirrors is arranged in the optical path of the first reflector and the second reflector, and the other group of plane mirrors is arranged in the optical path of the third reflector and the fourth reflector.

3. The interferometer based on double arm rotation as claimed in claim 1, characterized in that: The reflected light beam passes through the first reflector and the second reflector and reaches the plane mirror, and then is reflected back to the beam splitter.

4. The interferometer based on double arm rotation as claimed in claim 1, characterized in that: The transmitted light beam passes through the third and fourth reflectors and reaches another plane mirror, and then is reflected back to the beam splitter.

5. The interferometer based on double arm rotation as claimed in claim 1, characterized in that: The beam splitter is at 45° to the horizontal plane.

6. The interferometer based on double arm rotation as claimed in claim 1, characterized in that: When the interferometer is in an initial state, all the reflectors are at 45° to the horizontal plane.

7. The interferometer based on double arm rotation as claimed in claim 1, characterized in that: A collimating lens is provided between the light source and the beam splitter for collimating the light beam before entering the beam splitter.

8. The interferometer based on double arm rotation as claimed in claim 1, characterized in that: The movable arm has a set angle range within which rotation is allowed during rotation about the rotation axis.

9. The interferometer based on double arm rotation as claimed in claim 1, characterized in that: The first reflector, the second reflector, the third reflector and the fourth reflector are all square.

10. A working method based on the double-arm rotating interferometer according to any one of claims 1 to 9, characterized in that: The following steps are involved: After being collimated, the light source emits a reflected light beam and a transmitted light beam through a beam splitter; After the reflected light beam passes through the first reflector and the second reflector and reaches the plane mirror, it is reflected back to the beam splitter; After the transmitted light beam passes through the third and fourth reflectors and reaches another plane mirror, it is reflected back to the beam splitter; The beams reflected back to the beam splitter are recombined and directed through an imaging lens to a detector.

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