CN111426446A - Multichannel focusing laser differential interferometer - Google Patents
Multichannel focusing laser differential interferometer Download PDFInfo
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- CN111426446A CN111426446A CN202010328644.9A CN202010328644A CN111426446A CN 111426446 A CN111426446 A CN 111426446A CN 202010328644 A CN202010328644 A CN 202010328644A CN 111426446 A CN111426446 A CN 111426446A
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- G—PHYSICS
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M9/00—Aerodynamic testing; Arrangements in or on wind tunnels
- G01M9/02—Wind tunnels
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- G—PHYSICS
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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Abstract
The invention discloses a multi-channel focusing laser differential interferometer, and belongs to the field of hydromechanics measurement. The invention relates to a multi-channel focusing laser differential interferometer, which comprises a transmitting light path and a receiving light path, wherein the transmitting light path comprises: the device comprises a coherent light source generator, a beam splitter group, a reflector group, an optical lens group, a first polarizer group, a first prism group and a first convex lens group; the receiving light path comprises a second convex lens group, a second prism group, a second polarizer group and a photoelectric receiver. A beam of laser is divided into a plurality of beams of laser by utilizing a beam splitting lens group and a corresponding reflector group, and a plurality of focuses are formed in a focusing area after passing through an optical lens group, a first polarizer group, a first prism group and a first convex lens group, and then the plurality of focuses pass through a second convex lens group, a second prism group and a second polarizer group and enter an optoelectronic receiver and are converted into electric signals to be obtained by an acquisition system. The density pulsation information of a plurality of space measuring points in the flow field can be measured simultaneously, and the test efficiency is greatly improved.
Description
Technical Field
The invention belongs to the field of hydromechanics measurement, and particularly relates to a multi-channel focusing laser differential interferometer.
Background
Wind tunnel experiment is one of the important means of current stage aerodynamic research, and the flow field information can not be captured in the experiment without the support of flow field measuring equipment. The current quantitative experimental measurement means comprise a pressure sensor, a pitot tube, a hot wire anemometer and the like. However, the above measurement methods all have the disadvantages: pressure sensors such as a PCB (printed circuit board) can only capture pressure pulsation data on the wall surface and are not suitable for an extremely high temperature experimental environment; the pitot probe has larger size and low spatial resolution; hot wire anemometer probes are susceptible to damage, especially under high supersonic incoming flow conditions. At the present stage, high-precision density pulse information of the experimental flow field space point can be obtained through a focusing laser differential interferometer, and due to the non-intrusive characteristic, the pulse information cannot be damaged by high-speed incoming flow, so that the pulse information has strong superiority. However, the existing focusing laser differential interferometer has a single channel, only information of one measuring point can be obtained in each operation, and the measuring efficiency is very low.
Disclosure of Invention
Aiming at the defects or improvement requirements of the prior art, the invention provides a multi-channel focusing laser differential interferometer, which aims to divide a single laser beam emitted by a single laser into a plurality of laser beams by utilizing a beam splitter group and a corresponding reflector group, and then focus and measure density pulsation information at a plurality of measuring points, thereby providing the multi-channel focusing laser differential interferometer for wind tunnel density pulsation measurement, which can simultaneously measure the density pulsation information of a plurality of measuring points in a flow field.
In order to achieve the above object, the present invention provides a multi-channel focusing laser differential interferometer, which comprises a transmitting optical path and a receiving optical path; the emission light path includes: coherent light source generator, beam splitting mirror group, speculum group, optical lens group, first polarizer group, first prism group and first convex lens group, wherein:
the coherent light source generator is used for emitting a beam of parallel laser with the same phase and consistent polarization direction;
the beam splitting mirror group comprises a plurality of beam splitting mirrors and is used for splitting a beam of parallel laser emitted by the coherent light source generator into N beams of parallel laser with equal light intensity, wherein N is equal to the number of channels;
the reflector group comprises a plurality of reflectors and is used for changing the direction of the parallel laser;
a beam of parallel laser emitted by the coherent light source generator is divided into N parallel lasers with equal light intensity and same direction after passing through the beam splitting mirror group and the reflector group; one beam of parallel laser is emitted in each channel;
the optical lens group comprises N optical lenses, and the optical lenses are used for respectively diverging the parallel laser beams of each channel into conical laser beams;
the first polarizer group comprises N first polarizers, and the first polarizers are used for filtering out non-linearly polarized interference light rays in the conical laser beams of each channel;
the first prism group comprises N first prisms, and the first prisms are used for respectively separating the linear polarized light of each channel into two beams of polarized light with the same intensity and mutually vertical polarization directions according to a birefringence principle;
the first convex lens group comprises N first convex lenses, the first convex lenses are used for focusing two separated light beams with mutually vertical polarization directions in each channel into two separated focuses, and the two separated focuses of each channel are positioned in a focusing area;
the receiving light path comprises a second convex lens group, a second prism group, a second polarizer group and N photoelectric receivers, wherein:
the second convex lens group comprises N second convex lenses, and the second convex lenses are used for refocusing the laser beams diverged after each channel passes through the focusing area;
the second prism group is positioned behind the second convex lens group and forms symmetrical reaction with the first prism group; the second prism group comprises N second prisms, and the second prisms are used for combining two separated light beams in each channel;
the second polarizer group comprises N second polarizers, and the second polarizers are used for mixing the combined light beams so that the mixed light beams can carry out phase interference;
the photoelectric receiver is arranged at the focus position of the light beam at the tail end of each channel and used for converting the light intensity information into an electric signal.
Furthermore, the beam splitting ratio of the beam splitter ranges from 10:90 to 90: 10.
Further, the optical lens is a concave lens or a convex lens.
Further, the focal length and the size of the first convex lens and the second convex lens are the same.
Further, in the same channel, the position relationship among the optical lens, the first convex lens and the second convex lens conforms to the imaging theorem.
Further, in the same channel, the positional relationship among the optical lens, the first convex lens and the second convex lens satisfies the following formula:
1/(L1-f1)+1/L2＝1/f2
L3＝f2
wherein, L1Is the distance between the optical lens and the first convex lens, f1Is the focal length of the optical lens (positive for convex lenses; negative for concave lenses), (L)1-f1) Is the distance between the second convex lens and the photoreceiver, L2Is the distance between the first convex lens and the focal point of the light beam, and is also the distance between the second convex lens and the focal point of the light beam, f2Is the focal length of the first convex lens, L3Is the distance between the first prism and the first convex lens, and is also the second edgeThe distance between the mirror and the second convex lens.
Further, the first prism and the second prism are birefringent prisms and have the same splitting angle.
Further, the birefringent prism is a Wollaston prism or a Sanderson prism.
Further, in each channel, the optical lens, the first polarizing plate, the first prism, the first convex lens, the second prism, the second polarizing plate, and the photoelectric receiver are on the same central axis, and the central axis coincides with the optical path of the channel.
Further, by adjusting the position of each channel, the focus of each channel can be moved to the location of interest, respectively.
Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
(1) according to the multi-channel focusing laser differential interferometer provided by the invention, a single laser beam emitted by a single laser is divided into a plurality of laser beams by utilizing the beam splitting mirror group and the corresponding reflector group, and then the laser beams are focused at a plurality of measuring points, so that density pulsation information of a plurality of measuring points in a flow field can be obtained at each time, the experiment times are greatly reduced, the experiment efficiency of a wind tunnel is improved, and the experiment cost is saved;
(2) the multi-channel focusing laser differential interferometer provided by the invention has good consistency of the testing light beam of each channel, and can analyze the correlation of each measuring point by obtaining the density pulsation information of a plurality of measuring points in the same test train number and carrying out correlation processing on the experimental data of different measuring points, thereby deepening the understanding of the time coherence and the space coherence of the flow field structure.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
An example of a multi-channel focused laser differential interferometer is shown in fig. 1. In order to simultaneously acquire density pulsation data of a plurality of measuring points in a flow field, a specific implementation method of the invention is adopted, and more specifically, a four-channel focusing laser differential interferometer is built for simultaneously acquiring density pulsation data of four measuring points in the flow field.
In the four-channel laser differential interferometer, a single laser beam emitted by a laser is divided into four parallel laser beams with equal light intensity under the combined action of a beam splitting mirror group S and a reflector group M.
Wherein the beam splitter group comprises S1，S2And S3. The beam splitting ratio (reflected light intensity: transmitted light intensity) of the beam splitter is 50: 50. According to the difference of the number of channels, the splitting ratio of each beam splitter can be 10: 90-90: adjusted within 10.
The reflector set M includes M1，M2And M3. The laser beam direction is changed, so that each laser beam is respectively directed to each measuring point.
Optical lens group C in the figure1Comprising four convex lenses or concave lenses of the same focal length. For diffusing the laser beam of each channel into a cone beam.
In the figure, a set of polarizers P1Comprising four identical polarizers. The device is used for filtering out interference light rays with nonlinear polarization in the light beams of the channels.
The first prism group W in the figure1The device comprises four same Wollaston prisms, and is used for dividing polarized light of each channel into two beams of polarized light with the same intensity and mutually vertical polarization directions according to a birefringence principle. Other birefringent prisms such as Sanderson prisms may be substituted.
First convex lens group C in the figure2Comprises four sameAnd the convex lens is used for respectively focusing the two separated light beams with mutually vertical polarization directions of each channel into two separated focal points.
There will be a total of four focal points in the focal region a in the figure. By adjusting the position of each channel, each focus can be moved to the focused measuring point position respectively.
Second convex lens group C in the figure3Comprises four same convex lenses with the same size and focal length as the first convex lens group C2The same applies to the repolymerization of the diverging beam after passing through the focusing region.
The second Wollaston prism group W in the figure2Comprises four identical Wollaston prisms with the specification of the first Wollaston prism group W1The same applies to combining the two laser beams with a certain separation angle in each channel separately. And a prism group W1A symmetrical reaction is formed. Other birefringent prisms such as Sanderson prisms may be substituted.
In the figure, the second polarizer group P2Four identical polarizers are included and serve to mix the combined beams in each channel separately to enable phase interference.
The photo-receiver group D in the figure comprises four identical photo-receivers, and the function of the photo-receivers is to convert the light intensity signal of each channel into a voltage signal.
In the example, the optical lens group C1The first convex lens group C2And a second convex lens group C3The positional relationship therebetween conforms to the imaging theorem:
wherein, 1/(L)1-f1)+1/L2＝1/f2，L3＝f2，L1Is an optical lens group C1And the first convex lens group C2(L) in the form of a circle1-f1) Is the second convex lens group C3Distance from the photo-receiver group D, f1Is a lens C1L (positive for convex lenses; negative for concave lenses)2Is a first convex lens group C2The distance between the measuring point A and the second convex lens group C3And between measuring point ADistance, f2Is a first convex lens group C2L3Is a first prism group W1And the first convex lens group C2Is the distance between the second prism W2And a second convex lens C3The distance between them.
By reasonably selecting the elements forming the multi-channel focusing laser differential interferometer, the parameters are ensured to be appropriate, the positions and the angles of the elements are adjusted, each focus of a focusing area can be moved to a target measuring point, the density pulsation information of a plurality of target measuring points can be obtained simultaneously in the same test train number, the experimental efficiency is greatly improved, and correlation analysis can be performed through post-processing to obtain more flow field information.
It will be appreciated by those skilled in the art that the foregoing is only a preferred embodiment of the invention, and is not intended to limit the invention, such that various modifications, equivalents and improvements may be made without departing from the spirit and scope of the invention.
Claims (10)
1. A multi-channel focused laser differential interferometer, wherein the interferometer comprises a transmit optical path and a receive optical path; the emission light path includes: coherent light source generator, beam splitter group (S), reflector group (M), optical lens group (C)1) A first polarizer group (P)1) A first prism group (W)1) And a first convex lens group (C)2) Wherein:
the coherent light source generator is used for emitting a beam of parallel laser with the same phase and consistent polarization direction;
the beam splitting mirror group (S) comprises a plurality of beam splitting mirrors and is used for splitting a beam of parallel laser emitted by the coherent light source generator into N beams of parallel laser with equal light intensity, wherein N is equal to the number of channels;
the reflector group (M) comprises a plurality of reflectors for changing the direction of the parallel laser light;
a beam of parallel laser emitted by the coherent light source generator is divided into N parallel lasers with equal light intensity and same direction after passing through the beam splitting mirror group (S) and the reflector group (M); one beam of parallel laser is emitted in each channel;
the optical lens group (C)1) The device comprises N optical lenses, a light source and a light source, wherein the optical lenses are used for respectively diverging the parallel laser beams of each channel into conical laser beams;
the first set of polarizers (P)1) The device comprises N first polaroids, a first light source and a second polaroid, wherein the first polaroids are used for filtering out non-linearly polarized interference rays in each channel of conical laser beams;
the first prism group (W)1) The device comprises N first prisms, wherein the first prisms are used for respectively separating the linear polarized light of each channel into two beams of polarized light with the same intensity and mutually vertical polarization directions according to a birefringence principle;
the first convex lens group (C)2) The device comprises N first convex lenses, wherein the first convex lenses are used for focusing two separated light beams with mutually vertical polarization directions in each channel into two separated focal points, and the two separated focal points of each channel are positioned in a focusing area (A);
the receiving optical path comprises a second convex lens group (C)3) A second prism set (W)2) A second polarizer group (P)2) And N photo-receivers (D), wherein:
the second convex lens group (C)3) The laser device comprises N second convex lenses, wherein the second convex lenses are used for refocusing the laser beams diverged after each channel passes through a focusing area (A);
the second prism group (W)2) Is positioned on the second convex lens group (C)3) Then, the first prism group (W) is connected with1) A symmetrical reaction is formed; the second prism group (W)2) The system comprises N second prisms, wherein the second prisms are used for combining two separated light beams in each channel;
the second set of polarizers (P)2) The N second polaroids are used for mixing the combined light beams so that the mixed light beams can carry out phase interference;
and the photoelectric receiver (D) is arranged at the focus position of the light beam at the tail end of each channel and is used for converting the light intensity information into an electric signal.
2. The multi-channel focusing laser differential interferometer according to claim 1, wherein the beam splitting ratio of the beam splitter ranges from 10:90 to 90: 10.
3. The multi-channel focused laser differential interferometer according to claim 1, wherein the optical lens is a concave lens or a convex lens.
4. The multi-channel focused laser differential interferometer according to claim 1, wherein the first convex lens and the second convex lens have the same focal length and size.
5. The multi-channel focused laser differential interferometer according to claim 1, 3 or 4, wherein the optical lens, the first convex lens and the second convex lens in the same channel are in a position relationship according to the imaging theorem.
6. The multi-channel focusing laser differential interferometer according to claim 5, wherein the optical lens, the first convex lens and the second convex lens in the same channel satisfy the following formula:
1/(L1-f1)+1/L2＝1/f2
L3＝f2
wherein, L1Is the distance between the optical lens and the first convex lens, f1Is the focal length of the optical lens, (L)1-f1) Is the distance between the second convex lens and the photoreceiver (D), L2Is the distance between the first convex lens and the focal point of the light beam, and is also the distance between the second convex lens and the focal point of the light beam, f2Is the focal length of the first convex lens, L3The distance between the first prism and the first convex lens is also the distance between the second prism and the second convex lens.
7. The multi-channel focused laser differential interferometer according to claim 1 or 6, wherein the first prism and the second prism are birefringent prisms and have the same splitting angle.
8. The multi-channel focused laser differential interferometer of claim 7, wherein the birefringent prism is a Wollaston prism or a Sandson prism.
9. A multi-channel focusing laser differential interferometer according to claim 1, characterized in that, in each channel, the optical lens, the first polarizer, the first prism, the first convex lens, the second prism, the second polarizer and the photoreceiver (D) are on the same central axis, and the central axis coincides with the channel optical path.
10. A multi-channel focused laser differential interferometer as recited in claim 1, wherein the focal point of each channel can be moved to a position of interest by adjusting the position of each channel.
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Citations (5)
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| CN101943604A (en) * | 2009-09-30 | 2011-01-12 | 卢家金 | Temperature-measurement imaging system and measuring method thereof |
| CN105403533A (en) * | 2015-06-12 | 2016-03-16 | 苏州微纳激光光子技术有限公司 | Method for measuring optical nonlinearity of material through multiple channels |
| CN109154663A (en) * | 2016-02-26 | 2019-01-04 | 密歇根宇航公司 | For directly detecting the multicomponent Fabry-Perot etalon interferometer of laser radar |
| CN109540853A (en) * | 2013-06-26 | 2019-03-29 | 科磊股份有限公司 | For the defects detection of sample and the system and method for photoluminescence measurement |
| CN110686853A (en) * | 2019-10-18 | 2020-01-14 | 华中科技大学 | Focusing laser differential interferometer and non-intrusive method for measuring density pulsation of flow field of wind tunnel |
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2020
- 2020-04-23 CN CN202010328644.9A patent/CN111426446A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101943604A (en) * | 2009-09-30 | 2011-01-12 | 卢家金 | Temperature-measurement imaging system and measuring method thereof |
| CN109540853A (en) * | 2013-06-26 | 2019-03-29 | 科磊股份有限公司 | For the defects detection of sample and the system and method for photoluminescence measurement |
| CN105403533A (en) * | 2015-06-12 | 2016-03-16 | 苏州微纳激光光子技术有限公司 | Method for measuring optical nonlinearity of material through multiple channels |
| CN109154663A (en) * | 2016-02-26 | 2019-01-04 | 密歇根宇航公司 | For directly detecting the multicomponent Fabry-Perot etalon interferometer of laser radar |
| CN110686853A (en) * | 2019-10-18 | 2020-01-14 | 华中科技大学 | Focusing laser differential interferometer and non-intrusive method for measuring density pulsation of flow field of wind tunnel |
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Application publication date: 20200717 |