Switching type interference zero optical path positioning device and method

Abstract

The application discloses a switching type interference zero optical path positioning device, and relates to the technical field of optical mechanical devices, which comprises a light source, a beam splitter, a stationary mirror, a moving mirror and a photoelectric detector. The light source can generate collimated infrared light. A filter switching mechanism is arranged between the light source and the beam splitter. The filter switching mechanism is used for switching different bandwidth infrared band-pass filters, visible light cut-off filters or infrared light sources to an infrared light path position. The application further provides a switching type interference zero optical path positioning method. The range of the transmitted spectrum is changed by using the infrared band-pass filter. The cut-off filter is used for excluding visible light interference in an interference diagram while transmitting infrared light. The range of the interference coherence length can be changed by changing the spectral width of the transmitted filter. Since the zero optical path difference position is in the range of the coherence length, the interference zero optical path difference position can be quickly found and positioned.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical mechanical devices, in particular to a switching type interference zero optical path positioning device and method. BACKGROUND

[0002] Infrared interference spectrum measurement is to generate a sequence of infrared interference light at different positions in the spatial domain, which is received by a detector after passing through a sample. Since the sample will absorb the light intensity of different frequencies in the infrared light, the infrared light after irradiating the sample carries the information of the sample, and after being transformed into a spectrum, the infrared absorption or transmission spectrum of the sample is obtained.

[0003] In infrared interference measurement, no matter which interference structure is used, the interference zero optical path difference position needs to be accurately positioned. The interference zero optical path difference position is the position where the optical path of the measurement light and the optical path of the reference light in the interference are equal, and has the maximum light intensity. In infrared spectrum interference, the zero optical path difference position is always located at the interference peak value in the interference coherence length interval. For mid-infrared spectrum, the coherence length is several tens of microns; for near-infrared spectrum, the coherence length is only a few microns, so it is very difficult to find the coherence length range and then determine the zero optical path difference position.

[0004] At present, one method for finding the zero optical path difference position in infrared interference at home and abroad is to install a white light interference positioning device. The problem of this method is that a second set of interference devices is introduced, and it is difficult to adjust the coincidence of the two sets of interference light paths. If they are not coincident, positioning errors will be generated. Another method is to pre-mark the approximate position of the zero optical path difference, and then find the position by a laser interferometer cooperating with a displacement table to drive a moving mirror during subsequent measurement. Once the device deviates from the initial calibration position due to vibration during transportation, this method needs to be recalibrated, which is complex and inefficient. SUMMARY

[0005] The present application aims to provide a switching type interference zero optical path positioning device and method to solve the technical problem of difficult positioning of the zero optical path difference in the prior art.

[0006] The present application provides a switching type interference zero optical path positioning device, comprising a first light source, a beam splitter, a stationary mirror, a moving mirror and a photoelectric detector, the first light source can generate collimated infrared light, a filter switching mechanism is arranged between the first light source and the beam splitter;

[0007] The filter switching mechanism is used to switch different bandwidth infrared band-pass filters, visible light cut-off filters or second light sources to the infrared light path position, the second light source is an infrared light source, infrared light transmits through the filter switching mechanism and is incident on the beam splitter, the beam splitter can divide the infrared light into a reference beam and a measurement beam, the stationary mirror is arranged in the light path position of the reference beam, and the moving mirror is arranged in the light path position of the measurement beam, the light beams reflected by the stationary mirror and the moving mirror can coincide and generate interference phenomena, and the photodetector is used to detect the interference signal size.

[0008] Further, the filter switching mechanism comprises a baffle and a filter mounting seat;

[0009] The baffle is fixedly installed between the beam splitter and the first light source, a through groove for slidingly installing the filter mounting seat is formed in the inside of the baffle, and a through hole is formed in the baffle in a direction perpendicular to the through groove;

[0010] A plurality of filter loading holes are equidistantly installed on the filter mounting seat, and the through hole can be sequentially communicated with the plurality of filter loading holes when the filter mounting seat slides.

[0011] Further, a power mechanism for driving the reciprocating movement of the filter mounting seat is arranged below the filter mounting seat, the lower end of the through groove is open, and the lower side of the filter mounting mechanism is connected with the power mechanism.

[0012] Further, at least one side of the through hole has a notch.

[0013] Further, the filter switching mechanism comprises a rotating disc part and a poking part;

[0014] A plurality of loading holes are equidistantly formed on the circumferential surface of the rotating disc part, a loading seat for loading different bandwidth infrared band-pass filters, visible light cut-off filters or second light sources is installed in the loading hole, a bearing column is rotationally connected to the center of the side of the rotating disc part away from the loading seat, and the bearing column is fixedly installed between the beam splitter and the first light source.

[0015] The poking part comprises a poking block and a limiting structure, the poking block is arranged on one side of the rotating disc part, a driving motor is connected to the poking block, the driving motor is used to drive the rotation of the poking block so that the loading seat on the rotating disc part is intermittently poked to rotate, and the limiting structure is connected with the poking block and can maintain the position of the poked loading seat unchanged.

[0016] Further, the limiting structure comprises an open ring, the open ring is connected with the driving block through a linkage block so that the open ring can rotate with the driving block, the center of the open ring is coaxial with the output end of the driving motor, the driving block is located in the opening of the open ring, and a gap is arranged between the driving block and one end of the open ring for the loaded seat to pass out after being driven.

[0017] After the driving block drives the rotating disc to rotate, the other end of the open ring can slide against the outer circumferential surface of the two loaded seats to make at least one loaded seat be covered inside the open ring.

[0018] Further, the linkage block is in the shape of an arc, the linkage block is arranged on the side of the open ring away from the rotating disc, and the two ends of the linkage block are connected with the driving block and the open ring respectively.

[0019] The application further provides a positioning method of the switching type interference zero optical path positioning device.

[0020] S100, the filter switching device is used to switch the infrared band-pass filter with the first bandwidth into the infrared light path, the moving mirror is moved until the photodetector detects the obvious interference signal, and the position of the zero optical path is determined to be in the first coherence length range.

[0021] S200, the filter switching device is used to switch the infrared band-pass filter with the second bandwidth into the infrared light path, the moving mirror is moved until the photodetector detects the obvious interference signal, and the position of the zero optical path difference is narrowed to the second coherence length range.

[0022] S300, when the visible light affects the measurement, the filter switching device is used to switch the visible light cut-off filter into the infrared light path, the moving mirror is moved until the photodetector detects the obvious interference signal, and the position of the zero optical path difference is determined.

[0023] When the visible light does not affect the measurement, the filter switching device is used to switch the through hole into the infrared light path, the moving mirror is moved until the photodetector detects the obvious interference signal, and the position of the zero optical path difference is determined.

[0024] The first bandwidth is smaller than the second bandwidth.

[0025] The application further provides another positioning method of the switching type interference zero optical path positioning device.

[0026] T100, the filter switching device is used to switch the narrow-bandwidth infrared light source into the infrared light path, the moving mirror is moved until the photodetector detects the obvious interference signal, and the position of the zero optical path is determined to be in the first coherence length range.

[0027] T200, switching the second bandwidth infrared band-pass filter into the infrared light path by the filter switching device, moving the moving mirror until the photoelectric detector detects a significant interference signal, narrowing the position of the zero optical path difference to the second coherence length range;

[0028] T300, when the visible light affects the measurement, switching the visible light cut-off filter into the infrared light path by the filter switching device, moving the moving mirror until the photoelectric detector detects a significant interference signal, and determining the position of the zero optical path difference; or,

[0029] When the visible light does not affect the measurement, switching the through hole into the infrared light path by the filter switching device, moving the moving mirror until the photoelectric detector detects a significant interference signal, and determining the position of the zero optical path difference.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] (1) The infrared band-pass filter in the present application changes the range of the transmitted spectrum, and the cut-off filter eliminates the interference of visible light in the interference pattern while passing the infrared light. By changing the spectral width of the transmitted filter, the range of the interference coherence length can be changed. Since the position of the zero optical path difference is within the coherence length range, the position of the interference zero optical path difference can be quickly found and positioned. By gradually narrowing the position of the interference zero optical path difference point through different bandwidth infrared light, the process is convenient and fast.

[0032] (2) The narrow-band band-pass filter can be replaced by a narrow-bandwidth infrared light source installed on the filter switching device, which also has the effect of generating a coherence length of hundreds of microns.

[0033] (3) The present application does not need to introduce a white light interference system, nor does it need to use a separate laser interference system to position the zero optical path difference. At the same time, the present application does not need to adjust the infrared interference system and the white light or laser interference system to ensure that the light paths coincide, thus simplifying the structure. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0035] Figure 1 The structure diagram of the switching type interference zero path positioning device for the embodiments of the present application is shown in the figure.

[0036] Figure 2A first structural schematic diagram of the filter switching mechanism is provided for embodiments of the present invention;

[0037] Figure 3 for Figure 2 A schematic diagram of the installation structure of the intermediate filter switching mechanism;

[0038] Figure 4 This is a schematic diagram of a second structure for a filter switching mechanism provided in an embodiment of the present invention.

[0039] Figure label:

[0040] 1. First light source; 2. Converging mirror mounting base; 3. Adjustable aperture; 4. Filter mounting base; 5. Baffle; 6. Beam splitter; 7. Manual switching device; 8. Electric switching device; 9. Stationary mirror; 10. Moving mirror; 11. Turntable component; 12. Actuating component; 1101. Loading base; 1102. Bearing column; 1201. Actuating block; 1202. Drive motor; 1203. Opening ring; 1204. Linkage block. Detailed Implementation

[0041] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0042] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0043] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] The following is combined with Figure 1 This invention provides a switchable interferometric zero optical path difference positioning device, comprising a first light source 1, a converging mirror mounting base 2, an adjustable aperture 3, a beam splitter 6, a stationary mirror 9, a moving mirror 10, and a photodetector. The first light source 1 generates collimated infrared light. During infrared interference, the infrared light is split into a reference beam and a measurement beam by the beam splitter 6. The reference beam is reflected by a stationary mirror 9, while the measurement beam is reflected by a moving mirror 10. After the two beams recombine, interference occurs. When the optical path of the reference beam is equal to that of the measurement beam, the position of zero optical path difference is reached, generating the maximum light intensity signal. Without using other methods to narrow down the search area, directly locating this position of zero optical path difference in interference is extremely difficult.

[0047] Based on the above problems, in this embodiment of the invention, a filter switching mechanism is provided between the first light source 1 and the beam splitter 6. The filter switching mechanism is used to switch infrared bandpass filters, visible light cutoff filters or second light sources with different bandwidths to the infrared optical path position. The second light source is an infrared light source. The infrared light passes through the filter switching mechanism and is incident on the beam splitter 6. The beam splitter 6 can split the infrared light into a reference beam and a measurement beam. The stationary reflector 9 is set at the optical path position of the reference beam, and the moving reflector 10 is set at the optical path position of the measurement beam.

[0048] The first light source 1 is considered a divergent point source. It is collimated by a converging mirror on the converging mirror mount 2 without any aberrations. An adjustable aperture 3 is installed in the collimated optical path to achieve light intensity modulation; the aperture size is directly proportional to the light intensity. A filter switching device switches different filters, including a visible light cutoff filter, to the infrared optical path. After passing through the filter, the infrared light first enters the cubic beam splitter 6, where it is split into a reference beam and a measurement beam. The reference beam is reflected by the stationary mirror 9; simultaneously, the measurement beam is reflected by the moving mirror 10. The two beams recombine and interfere with each other at the photodetector.

[0049] The function of an infrared bandpass filter is to change the range of the transmitted spectrum, while the function of a cutoff filter is to allow infrared light to pass while simultaneously eliminating interference from visible light in the interferogram. By changing the spectral width of the transmission filter, the range of the interference coherence length can be altered. Since the zero optical path difference position is within the coherence length range, the zero optical path difference position in the interference can be quickly located and positioned.

[0050] In this embodiment of the invention, a filter switching device is first used to switch the infrared narrowband bandpass filter to the interference optical path. According to optical interference theory, the interference light spectrum is narrow, while the coherence length range generated by the interference is wide. The narrowband bandpass filter can make the interference coherence length distance on the order of hundreds of micrometers. By moving the moving mirror 10 of the measuring branch optical path in the moving infrared interferometer, the optical path difference is kept within the coherence length range.

[0051] Next, a filter switching device is used to switch a wider infrared bandpass filter into the interference optical path, so that the interference coherence length is on the order of ten micrometers. Then, the motion mirror 10 is moved to the new coherence length range to further narrow the search range for the zero optical path difference position point of the interference.

[0052] The next step is to use a filter switching device to switch the visible light cutoff filter to the optical path. If the visible light does not affect the measurement, it can be switched to a through hole so that the interference coherence length is on the order of hundreds of nanometers. By moving the mirror, a nanometer displacement scan is performed within the range to locate the zero optical path difference position.

[0053] The present invention can also replace the narrowband bandpass filter with a narrowband infrared light source and install it on the filter switching device, which can also achieve the effect of generating a coherence length on the order of hundreds of micrometers.

[0054] Specifically, such as Figure 2 As shown, the filter switching mechanism includes a baffle 5 and a filter mounting base 4;

[0055] The baffle 5 is fixedly installed between the beam splitter 6 and the first light source 1. A through groove is provided inside the baffle 5 for the filter mounting base 4 to slide and install. A through hole is provided on the baffle 5 in a direction perpendicular to the through groove.

[0056] Multiple filter mounting holes are equidistantly installed on the filter mounting base 4. When the filter mounting base 4 slides, the through holes can sequentially communicate with the multiple filter mounting holes.

[0057] The filter mounting base 4 here can be slid by hand, but this method is greatly affected by human factors and the operation is uncontrollable;

[0058] Therefore, as Figure 3 As shown, in this embodiment of the invention, a power mechanism for driving the filter mounting base 4 to reciprocate is provided below the filter mounting base 4. The lower end of the through slot is open, and the lower part of the filter mounting base is connected to the power mechanism.

[0059] The power mechanism here can be a manually operated switching device 7, such as a lead screw rotation, or an electrically operated switching device 8, such as a motor drive.

[0060] Furthermore, since the narrow-bandwidth infrared light source can also replace the narrow-bandband bandpass filter in the embodiments of the present invention, and the part of the narrow-bandwidth infrared light source that protrudes from the through hole may affect the sliding of the filter mounting base 4 when it is installed at the through hole, at least one side of the through hole has a notch facing the side of the narrow-bandwidth infrared light source.

[0061] The aforementioned filter switching mechanism can switch between infrared bandpass filters, visible light cutoff filters, or second light sources with different bandwidths. However, since the long strip-shaped filter mounting base 4 can only move back and forth, the entire filter mounting base 4 needs to be moved to the initial position during the next positioning process. The movement distance is large, making the operation inconvenient. Therefore, this embodiment of the invention also provides a specific structure of a turntable-type filter switching mechanism:

[0062] like Figure 4 As shown, it includes a turntable 11 and a toggle 12; a plurality of mounting holes 1101 are equally spaced on the circumferential surface of the turntable 11, and a mounting seat for mounting infrared bandpass filters, visible light cutoff filters or second light sources of different bandwidths is installed in the mounting holes 1101. A bearing column 1102 is rotatably connected to the center of the side of the turntable 11 away from the mounting seat, and the bearing column 1102 is fixedly installed between the beam splitter 6 and the first light source 1.

[0063] The actuating component 12 includes an actuating block 1201 and a limiting structure. The actuating block 1201 is disposed on one side of the turntable component 11. The actuating block 1201 is connected to a drive motor 1202. The drive motor 1202 is used to drive the actuating block 1201 to rotate so that the actuating block 1201 intermittently actuates the loading seat on the turntable component 11. The limiting structure is connected to the actuating block 1201. The limiting structure can maintain the position of the loading seat after actuation, thereby ensuring the stability of the filter switching mechanism during the search for the zero optical path difference position.

[0064] Specifically, the limiting structure includes an open ring 1203, which is connected to the actuating block 1201 via a linkage block 1204 so that the open ring 1203 can rotate together with the actuating block 1201. The center of the open ring 1203 is coaxial with the output end of the drive motor 1202. The actuating block 1201 is located inside the opening of the open ring 1203, and a gap is left between the actuating block 1201 and one end of the open ring 1203 for the loading seat to pass through after being actuated.

[0065] After the toggle block 1201 causes the turntable 11 to rotate, the other end of the open ring 1203 can slide against the outer peripheral surfaces of the two alternating loading seats so that at least one loading seat is covered inside the open ring 1203.

[0066] The actuating block 1201 here can intermittently contact the loading seat and actuate the turntable 11 connected to the loading seat to rotate. Therefore, the interval of the intermittent rotation can be controlled. Within this interval, the zero optical path difference position can be located. After each glass slide is switched, a fixed time is paused to find the zero optical path difference position, and then the rotation is automatically started and the next glass slide is switched.

[0067] Meanwhile, based on the aforementioned limiting structure, since the open ring 1203 slides against the outer peripheral surfaces of the two alternating loading seats, the open ring 1203 effectively locks the position of the turntable 11. The turntable 11 cannot rotate until the actuating block 1201 contacts and actuates the loading seat. During installation, the loading seat enclosed in the open ring 1203 can be selected as a detection point in the infrared optical path. All infrared bandpass filters, visible light cutoff filters, or second light sources of different bandwidths pass sequentially through this detection point. This detection point is confined within the open ring 1203 and cannot move, thus ensuring the accuracy of zero optical path difference positioning.

[0068] In addition, in this embodiment of the invention, the linkage block 1204 is used to connect the actuating block 1201 and the open ring 1203. On the one hand, it installs and fixes the open ring 1203, and on the other hand, it allows the open ring 1203 to move together with the actuating block 1201. In order not to affect the actuation of the actuating block 1201, the linkage block 1204 can be set on the side of the open ring 1203 away from the turntable 11. However, this setting will also cause the linkage block 1204 to block the loading seat when it rotates to the loading seat at the detection point during the rotation of the open ring 1203, thereby affecting the accuracy of the zero optical path difference position positioning.

[0069] Based on the above considerations, in this embodiment of the invention, the linkage block 1204 is set in an arc shape. The linkage block 1204 is located on the side of the open ring 1203 away from the turntable 11. The two ends of the linkage block 1204 are respectively connected to the actuating block 1201 and the open ring 1203. Since the arched arc shape achieves the connection between the actuating block 1201 and the open ring 1203 without affecting the gap left between the actuating block 1201 and the open ring 1203, and does not obstruct the loading seat of the detection point.

[0070] The present invention also provides a positioning method for a switching interferometric zero optical path positioning device, comprising the following steps:

[0071] S100: Use the filter switching device to switch the infrared bandpass filter with the first bandwidth to the infrared optical path, move the motion mirror 10 until the photodetector detects a significant interference signal, and determine the position of zero optical path within the first coherence length range.

[0072] S200: Use the filter switching device to switch the second bandwidth infrared bandpass filter to the infrared optical path, move the motion mirror 10 until the photodetector detects a significant interference signal, and reduce the position of zero optical path difference to within the second coherence length range.

[0073] S300. When measuring the influence of visible light, the visible light cutoff filter is switched to the infrared optical path using a filter switching device. The moving reflector 10 is moved until the photodetector detects a significant interference signal, thus determining the position of zero optical path difference; or...

[0074] When visible light does not affect the measurement, the filter switching device is used to switch the through hole to the infrared optical path, and the moving mirror 10 is moved until the photodetector detects a significant interference signal to determine the position of zero optical path difference.

[0075] The first bandwidth is less than the second bandwidth.

[0076] The present invention also provides another positioning method for a switching interferometric zero optical path positioning device, comprising the following steps:

[0077] T100: Use the filter switching device to switch the narrow bandwidth infrared light source to the infrared optical path, move the motion mirror 10 until the photodetector detects a significant interference signal, and determine the position of zero optical path within the first coherence length range.

[0078] T200: Use the filter switching device to switch the second bandwidth infrared bandpass filter to the infrared optical path, move the motion mirror 10 until the photodetector detects a significant interference signal, and reduce the position of zero optical path difference to within the second coherence length range.

[0079] T300, when measuring the influence of visible light, use the filter switching device to switch the visible light cutoff filter to the infrared optical path, and move the motion reflector 10 until the photodetector detects a significant interference signal to determine the position of zero optical path difference; or...

[0080] When visible light does not affect the measurement, the through hole is switched to the infrared optical path using a filter switching device, and the moving mirror 10 is moved until the photodetector detects a significant interference signal to determine the position of zero optical path difference.

[0081] In this embodiment of the invention, the switching interferometric zero-optical-path positioning device, when applied to actual zero-optical-path difference positioning, first uses a filter switching device to switch a 1550nm infrared narrow-band bandpass filter to the interference optical path. The filter bandwidth is 20nm. According to optical interference theory, a narrow spectral range of interference light results in a wide range of coherence lengths. Calculations show that this narrow-band bandpass filter can achieve an interference coherence length of 120 nm. μm At any point within the coherence length, a clear interference signal can be read out on the photodetector. Therefore, by moving the motion mirror 10 in the infrared interferometer so that the optical path difference is within the coherence length, the approximate location range of zero optical path difference can be preliminarily determined.

[0082] Next, a filter switching device is used to switch a wider infrared bandpass filter into the interference optical path, so that the interference coherence length is on the order of ten micrometers. Then, the motion mirror 10 is moved to the new coherence length range to further narrow the search range for the zero optical path difference position point of the interference.

[0083] The next step is to use a filter switching device to switch the visible light cutoff filter below 900nm to the optical path. If the visible light does not affect the measurement, it can be switched to a through hole so that the interference coherence length is on the order of hundreds of nanometers. By moving the mirror, a nanometer displacement scan is performed within the range to locate the zero optical path difference position.

[0084] The present invention can also replace the narrowband bandpass filter with a second light source, which is a narrowband wide infrared light source with a center wavelength of 1310nm and an emission spectrum width of 120nm. It is installed on the filter switching device and achieves the same effect of generating a coherence length on the order of hundreds of micrometers.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A switching interferometric zero optical path positioning device, characterized in that, It includes a first light source (1), a beam splitter (6), a stationary reflector (9), a moving reflector (10), and a photodetector. The first light source (1) can generate collimated infrared light. A filter switching mechanism is provided between the first light source (1) and the beam splitter (6). The filter switching mechanism is used to switch infrared bandpass filters, visible light cutoff filters or second light sources with different bandwidths to the infrared light path position. The second light source is an infrared light source. Infrared light passes through the filter switching mechanism and is incident on the beam splitter (6). The beam splitter (6) can split the infrared light into a reference beam and a measurement beam. The stationary reflector (9) is set at the optical path position of the reference beam. The moving reflector (10) is set at the optical path position of the measurement beam. The beams reflected by the stationary reflector (9) and the moving reflector (10) can overlap and generate interference. The photodetector is used to detect the magnitude of the interference signal.

2. The switching interferometric zero optical path positioning device according to claim 1, characterized in that, The filter switching mechanism includes a baffle (5) and a filter mounting base (4). The baffle (5) is fixedly installed between the beam splitter (6) and the first light source (1). A through groove is provided inside the baffle (5) for the filter mounting base (4) to be slidably installed. A through hole is provided on the baffle (5) in a direction perpendicular to the through groove. Multiple filter loading holes are equidistantly installed on the filter mounting base (4). When the filter mounting base (4) slides, the through holes can sequentially communicate with the multiple filter loading holes.

3. The switching interferometric zero optical path positioning device according to claim 2, characterized in that, A power mechanism for driving the reciprocating movement of the filter mounting base (4) is provided below the filter mounting base (4). The lower end of the through slot is open, and the lower part of the filter mounting base (4) is connected to the power mechanism.

4. The switching interferometric zero optical path positioning device according to claim 2, characterized in that, The through hole has a notch on at least one side.

5. The switching interferometric zero optical path positioning device according to claim 1, characterized in that, The filter switching mechanism includes a turntable (11) and a toggle (12). Multiple mounting holes are equidistantly provided on the circumferential surface of the turntable (11). A mounting base (1101) for mounting infrared bandpass filters, visible light cutoff filters or second light sources with different bandwidths is installed in the mounting holes. A bearing column (1102) is rotatably connected to the center of the side of the turntable (11) away from the mounting base (1101). The bearing column (1102) is fixedly installed between the beam splitter (6) and the first light source (1). The actuating component (12) includes an actuating block (1201) and a limiting structure. The actuating block (1201) is disposed on one side of the turntable component (11). The actuating block (1201) is connected to a drive motor (1202). The drive motor (1202) is used to drive the actuating block (1201) to rotate so that the actuating block (1201) intermittently actuates the loading seat (1101) on the turntable component (11) to rotate. The limiting structure is connected to the actuating block (1201) and can maintain the position of the loading seat (1101) after actuation.

6. The switching interferometric zero optical path positioning device according to claim 5, characterized in that, The limiting structure includes an open ring (1203), which is connected to the actuating block (1201) via a linkage block (1204) so ​​that the open ring (1203) can rotate together with the actuating block (1201). The center of the open ring (1203) is coaxial with the output end of the drive motor (1202). The actuating block (1201) is located inside the opening of the open ring (1203), and a gap is left between the actuating block (1201) and one end of the open ring (1203) for the loading seat (1101) to pass through after being actuated. After the actuating block (1201) actuates the turntable (11) to rotate, the other end of the opening ring (1203) can slide against the outer peripheral surfaces of the two alternating loading seats (1101) so that at least one loading seat (1101) is covered inside the opening ring (1203).

7. The switching interferometric zero optical path positioning device according to claim 6, characterized in that, The linkage block (1204) is arc-shaped and is located on the side of the open ring (1203) away from the turntable (11). The two ends of the linkage block (1204) are respectively connected to the toggle block (1201) and the open ring (1203).

8. A positioning method for the switching interferometric zero optical path positioning device as described in any one of claims 1-7, characterized in that, Includes the following steps: S100. Use the filter switching mechanism to switch the infrared bandpass filter of the first bandwidth to the infrared optical path, move the motion mirror (10) until the photodetector detects a significant interference signal, and determine the position of zero optical path within the first coherence length range. S200, using the filter switching mechanism to switch the second bandwidth infrared bandpass filter to the infrared optical path, move the motion reflector (10) until the photodetector detects a significant interference signal, and reduce the position of zero optical path difference to within the second coherence length range; S300. When measuring the influence of visible light, the visible light cutoff filter is switched to the infrared optical path using the filter switching mechanism. The moving reflector (10) is moved until the photodetector detects a significant interference signal, thus determining the position of zero optical path difference; or, When visible light does not affect the measurement, the filter switching mechanism is used to switch the through hole to the infrared optical path, and the moving reflector (10) is moved until the photodetector detects a significant interference signal to determine the position of zero optical path difference; The first bandwidth is less than the second bandwidth.

9. A positioning method for the switching interferometric zero optical path positioning device as described in any one of claims 1-7, characterized in that, Includes the following steps: T100. Use the filter switching mechanism to switch the narrow bandwidth infrared light source to the infrared optical path, move the motion reflector (10) until the photodetector detects a significant interference signal, and determine the position of zero optical path within the first coherence length range. T200, using the filter switching mechanism to switch the second bandwidth infrared bandpass filter to the infrared optical path, move the motion reflector (10) until the photodetector detects a significant interference signal, and reduce the position of zero optical path difference to within the second coherence length range; T300, When measuring the influence of visible light, the visible light cutoff filter is switched to the infrared optical path using the filter switching mechanism. The moving reflector (10) is moved until the photodetector detects a significant interference signal, thus determining the position of zero optical path difference; or, When visible light does not affect the measurement, the filter switching mechanism is used to switch the through hole to the infrared optical path, and the motion mirror (10) is moved until the photodetector detects a significant interference signal to determine the position of zero optical path difference.

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