阅读说明：本技术 一种基于马赫-泽德干涉的旋转体角速度光学测量系统 (Optical measurement system for angular velocity of rotating body based on Mach-Zehnder interference ) 是由 董毅 张艳玲 田娅 于 2019-11-28 设计创作，主要内容包括：本发明的基于马赫-泽德干涉的旋转体角速度光学测量系统,包括激光光源、第一偏和第二偏振分束镜、分光棱镜、螺旋相位片、四分之一波片和光电探测器,信号光经螺旋相位片转化为涡旋光,涡旋光经四分之一波片后垂直照射于待测旋转体上,反射后相对于初始涡旋光发生90°旋转；第二偏振分束镜透射的参考光与其反射的信号光汇成一路光束,照射于偏振片上,信号光和参考光经偏振片后偏振方向同向,照射于分光棱镜上。本发明的旋转体角速度光学测量系统,可调节经信号光与参考光的光强比,以使发生干涉时的参考光与信号光的光强比相等,发生干涉时信号光与参考光的光强相等,使得光电探测器获得最大的差频信号,保证了旋转体转动角速度的测量精度。(The invention relates to a Mach-Zehnder interference-based rotator angular velocity optical measurement system which comprises a laser light source, a first polarization beam splitter, a second polarization beam splitter, a beam splitter prism, a spiral phase plate, a quarter wave plate and a photoelectric detector, wherein signal light is converted into vortex rotation through the spiral phase plate, the vortex rotation vertically irradiates on a rotator to be measured after passing through the quarter wave plate, and rotates for 90 degrees relative to initial vortex rotation after being reflected; the reference light transmitted by the second polarization beam splitter and the signal light reflected by the second polarization beam splitter are converged into a light beam and irradiated on the polarizer, and the signal light and the reference light are irradiated on the beam splitter prism in the same polarization direction after passing through the polarizer. The optical measuring system for the angular velocity of the rotating body can adjust the light intensity ratio of the signal light to the reference light, so that the light intensity ratio of the reference light to the signal light is equal when interference occurs, and the light intensity of the signal light is equal to that of the reference light when interference occurs, so that a photoelectric detector obtains the largest difference frequency signal, and the measuring precision of the rotating angular velocity of the rotating body is ensured.)

1. A rotator angular velocity optical measurement system based on Mach-Zehnder interference comprises a laser source (1), a first polarization beam splitter (5), a second polarization beam splitter (8), a beam splitter prism (13), a spiral phase plate (7), a quarter wave plate (9) and a photoelectric detector, wherein the laser source is used for generating linear polarization laser, the laser irradiates the first polarization beam splitter after rotating the polarization direction through a half wave plate, and transmitted light and reflected light of the laser after passing through the first polarization beam splitter are respectively used as signal light and reference light; the method is characterized in that: the signal light is converted into linear polarization vortex rotation with the angular quantum number of l through the spiral phase plate (7), vortex light irradiates on the second polarization beam splitter (8), the second polarization beam splitter realizes complete transmission of the vortex rotation irradiated on the second polarization beam splitter, and the vortex light transmitted by the second polarization beam splitter vertically irradiates on a rotating body (10) to be measured after passing through the quarter-wave plate (9); the vortex optical rotation irradiated on the rotating body to be detected is reflected and then passes through the quarter-wave plate again, the polarization direction of vortex light rotates for 90 degrees relative to the initial vortex optical rotation, the rotated vortex light is irradiated on a second polarization beam splitter (8), and the second polarization beam splitter enables the vortex light after the rotation direction to be totally reflected;

an optical rotation sheet (11) is arranged between the first polarization beam splitter and the second polarization beam splitter, and a polarizing sheet (12) is arranged between the second polarization beam splitter and the beam splitter prism (13); the reference light formed by reflection of the first polarization beam splitter is irradiated on the second polarization beam splitter after rotating the polarization direction through the optical rotation sheet (11), and the second polarization beam splitter enables all the reference light irradiated on the second polarization beam splitter to transmit; the reference light transmitted by the second polarization beam splitter and the signal light reflected by the reference light are converged into a light beam and irradiated on a polarizing film (12), and the signal light and the reference light are irradiated on a beam splitter prism (13) in the same polarization direction after passing through the polarizing film; the signal light and the reference light with the same polarization direction are subjected to optical heterodyne interference, and the photoelectric detector is used for detecting a difference frequency signal of the signal light and the reference light.

2. A mach-zehnder interferometer based rotor angular velocity optical measurement system in accordance with claim 1, wherein: a beam expander (3) is arranged between the laser source (1) and the half-wave plate (4), and laser emitted by the laser source is expanded by the beam expander and then irradiates the half-wave plate; a right-angle prism (6) is arranged between the first polarization beam splitter (5) and the spiral phase plate (7), and the signal light entering and exiting from the right-angle prism has opposite propagation directions and is strictly parallel.

3. A mach-zehnder interferometer based rotor angular velocity optical measurement system according to claim 1 or 2, characterized in that: the photoelectric detector comprises a first photoelectric detector (16) and a second photoelectric detector (17), interference optical signals of signal light and reference light reflected by the light splitting prism (13) are converged by the first converging lens (14) and then irradiate the first photoelectric detector (16), and interference optical signals transmitted by the light splitting prism are converged by the second converging lens and then irradiate the second photoelectric detector (17).

4. A mach-zehnder interferometer based rotor angular velocity optical measurement system according to claim 1 or 2, characterized in that: the half-wave plate (4), the optical rotation plate (11) and the polaroid (12) can be rotationally adjusted, the optical rotation plate enables the polarization direction of the reference light irradiated on the optical rotation plate to rotate by 90 degrees, and the polaroid enables the polarization directions of the reference light and the signal light irradiated on the optical rotation plate to be the same.

5. A mach-zehnder interferometer based rotor angular velocity optical measurement system in accordance with claim 3, wherein: if the number of angular quanta of the spiral phase plate is l, and a difference frequency signal obtained after random noise is filtered by the first photoelectric detector (16) and the second photoelectric detector (17) is delta f, the following conditions are met:

from equation (1):

wherein l is the angular quantum number of the spiral phase plate, and Δ f is the frequency of the difference frequency signal measured by the detector.

Technical Field

The invention relates to an optical measuring system for angular velocity of a rotating body, in particular to an optical measuring system for angular velocity of a rotating body based on Mach-Zehnder interference.

Background

The vortex light is singular light with a spiral wave front structure, and the center of the light beam of the vortex light is provided with a phase singularity, so that the light intensity of the cross section of the vortex light is distributed in an annular hollow shape. When a vortex light with orbital angular momentum is directed perpendicularly along the axis of rotation onto a rough surface of a rotating body, a frequency shift phenomenon, known as rotational doppler shift, occurs. By using the rotary doppler effect, the measurement of the angular velocity of the rotor can be achieved.

Generally, the frequency of the light waves used for Doppler shift is extremely high, at 10¹⁴At around Hz, conventional photo-detector devices cannot respond directly to such high frequencies. Optical heterodyne detection is a common laser doppler detection technique. When two light waves from the same coherent light source are projected on the surface of the light detector according to a certain condition, the frequency difference between the two light waves can be obtained through the square rate effect of photoelectric conversion. This frequency difference is the required doppler shift.

The optical arrangement of linear doppler shift optical heterodyne detection has several fundamental modes: a reference light mode, a single beam-double scattering mode, and a double beam-double scattering mode. For the lateral Doppler effect, on one hand, at least one path of the signal light and the reference light needs to be vortex rotation; on the other hand, due to the rotational symmetry of the object to be measured, the signal light is parallel to the rotation axis of the object to be measured. Therefore, none of these modes of linear doppler shift optical heterodyne detection is suitable for lateral doppler shift detection.

Disclosure of Invention

In order to overcome the defects of the technical problems, the invention provides an optical measuring system for the angular velocity of a rotating body based on Mach-Zehnder interference.

The invention relates to a rotator angular velocity optical measurement system based on Mach-Zehnder interference, which comprises a laser source, a first polarization beam splitter, a second polarization beam splitter, a beam splitter prism, a spiral phase plate, a quarter wave plate and a photoelectric detector, wherein the laser source is used for generating linear polarization laser, the laser irradiates the first polarization beam splitter after rotating the polarization direction through a half wave plate, and transmitted light and reflected light of the laser after passing through the first polarization beam splitter are respectively used as signal light and reference light; the method is characterized in that: the signal light is converted into linear polarization vortex rotation with the angular quantum number of l through the spiral phase plate, vortex light irradiates on the second polarization beam splitter, the second polarization beam splitter realizes complete transmission of the vortex rotation irradiated on the second polarization beam splitter, and the vortex light transmitted by the second polarization beam splitter vertically irradiates on a rotating body to be measured after passing through the quarter wave plate; the vortex optical rotation irradiated on the rotating body to be detected is reflected and then passes through the quarter-wave plate again, the polarization direction of vortex light rotates for 90 degrees relative to the initial vortex optical rotation, the rotated vortex light is irradiated on a second polarization beam splitter, and the second polarization beam splitter enables the vortex light after the rotation direction to be totally reflected;

an optical rotation sheet is arranged between the first polarization beam splitter and the second polarization beam splitter, and a polarizing sheet is arranged between the second polarization beam splitter and the light splitting prism; the reference light formed by reflection of the first polarization beam splitter is irradiated on the second polarization beam splitter after the polarization direction is rotated by the optical rotation sheet, and the second polarization beam splitter enables all the reference light irradiated on the second polarization beam splitter to be transmitted; the reference light transmitted by the second polarization beam splitter and the signal light reflected by the second polarization beam splitter are converged into a light beam and irradiated on the polarizer, and the signal light and the reference light are irradiated on the beam splitter prism in the same polarization direction after passing through the polarizer; the signal light and the reference light with the same polarization direction are subjected to optical heterodyne interference, and the photoelectric detector is used for detecting a difference frequency signal of the signal light and the reference light.

According to the optical measuring system for the angular velocity of the rotator based on the Mach-Zehnder interference, the beam expander is arranged between the laser source and the half-wave plate, and laser emitted by the laser source is expanded by the beam expander and then irradiates the half-wave plate; a right-angle prism is arranged between the first polarization beam splitter and the spiral phase plate, and the signal light incident and emergent from the right-angle prism has opposite propagation directions and is strictly parallel.

The invention relates to a Mach-Zehnder interference-based rotating body angular velocity optical measuring system, wherein a photoelectric detector comprises a first photoelectric detector and a second photoelectric detector, interference optical signals of signal light and reference light reflected by a beam splitter prism are converged by a first converging lens and then irradiated on the first photoelectric detector, and interference optical signals transmitted by the beam splitter prism are converged by a second converging lens and then irradiated on the second photoelectric detector.

The optical measurement system of the angular velocity of the rotator based on the Mach-Zehnder interference can carry out rotation adjustment on the half-wave plate, the optical rotation plate and the polaroid, the optical rotation plate enables the polarization direction of the reference light irradiated on the optical rotation plate to rotate by 90 degrees, and the polaroid enables the polarization directions of the reference light and the signal light irradiated on the optical rotation plate to be the same.

The optical measurement system for the angular velocity of the rotator based on the Mach-Zehnder interference provided by the invention has the following advantages that the angular quantum number of the spiral phase plate is set to be l, and the difference frequency signal obtained after random noise is filtered by the first photoelectric detector and the second photoelectric detector is set to be delta f, so that the following requirements are met:

from equation (1):

wherein l is the angular quantum number of the spiral phase plate, and Δ f is the frequency of the difference frequency signal measured by the detector.

The invention has the beneficial effects that: according to the rotator angular velocity optical measurement system, laser generated by a laser source is irradiated on a first polarization beam splitter after rotating the polarization direction through a half-wave plate, generated transmission light and generated reflection light are respectively used as signal light and reference light, the signal light is totally reflected twice through a right-angle prism, converted into vortex rotation through a spiral phase plate in an antiparallel light mode, sequentially irradiated on a rotator to be measured through a second polarization beam splitter and a quarter-wave plate, and the vortex rotation reflected by the rotator to be measured is rotated by 90 degrees in the polarization direction after passing through the quarter-wave plate again; the reference light and the vortex signal light are converged into a light beam after the polarization direction of the reference light is changed by the optical rotation sheet, the signal light and the reference light which are converged into the light beam are polarized to be the same through the polarizing sheet so as to generate optical heterodyne interference, and a difference frequency signal of the interfered signal light and the reference light is detected by the photoelectric detector, so that the rotation angular speed of the rotating body is measured.

According to the rotator angular velocity optical measurement system, the light intensity ratio of the signal light and the reference light formed by transmission and reflection of the first polarization beam splitter can be adjusted by rotating the half-wave plate, so that the light intensity ratio of the reference light and the signal light is equal when interference occurs, and the polarization direction of the reference light can rotate by 90 degrees by rotating the optical rotation plate, so that the reference light completely penetrates through the second polarization beam splitter; when interference occurs, the light intensity of the signal light is equal to that of the reference light, so that the photoelectric detector obtains the maximum difference frequency signal, and the measurement accuracy of the rotating angular speed of the rotating body is ensured.

Drawings

FIG. 1 is a schematic diagram of an optical measurement system for angular velocity of a rotating body based on Mach-Zehnder interference according to the present invention.

In the figure: the device comprises a laser light source 1, a total reflector 2, a beam expander 3, a half-wave plate 4, a first polarization beam splitter 5, a right-angle prism 6, a spiral phase plate 7, a second polarization beam splitter 8, a quarter-wave plate 9, a rotating body to be measured 10, an optical rotation plate 11, a polarizing plate 12, a beam splitter prism 13, a first converging lens 14, a second converging lens 15, a first photoelectric detector 16 and a second photoelectric detector 17.

Detailed Description

The invention is further described with reference to the following figures and examples.

As shown in fig. 1, a schematic diagram of an optical measurement system for angular velocity of a rotator based on mach-zehnder interference according to the present invention is provided, which is composed of a laser source 1, a total reflection mirror 2, a beam expander 4, a first polarization beam splitter 5, a right-angle prism 6, a spiral phase plate 7, a second polarization beam splitter 8, a quarter-wave plate 9, an optical rotation plate 11, a polarizing plate 12, a beam splitter prism 13, a first converging lens 14, a second converging lens 15, a first photodetector 16, and a second photodetector 17, wherein the laser source 1 is configured to generate linearly polarized laser light, and all optical elements in the same direction are coaxial. A total reflector 2, a beam expander 3 and a half-wave plate 4 are sequentially arranged between a laser source 1 and a first polarization beam splitter 5, laser emitted by the laser source 1 is reflected by the total reflector 2 and then expanded by the beam expander 3, the expanded laser irradiates the first polarization beam splitter 5 after rotating the polarization direction by the half-wave plate 4, and transmitted light and reflected light irradiated on the first polarization beam splitter 5 are respectively used as signal light and reference light. The polarization direction of the laser is adjusted by rotating the half-wave plate 4, and the light intensity ratio of the signal light and the reference light generated by the laser through the first polarization beam splitter 5 can be adjusted, so that the light intensity of the signal light and the reference light is equal when interference finally occurs.

The spiral phase plate 7 is located between the right-angle prism 6 and the second polarization beam splitter 8, the quarter-wave plate 9 is located between the second polarization beam splitter 8 and the rotating body 10 to be tested, the signal light formed by the transmission of the laser through the first polarization beam splitter 5 is P polarized light, and the signal light irradiates the spiral phase plate 7 in an anti-parallel light mode after being totally reflected twice by the right-angle prism 6. The spiral phase plate 7 converts the linearly polarized light irradiated on the spiral phase plate into vortex light with an angular quantum number of l, the vortex light is irradiated on the second polarization beam splitter 8, and the second polarization beam splitter 8 is placed to meet the following requirements: the linearly polarized vortex light impinging thereon is fully transmitted. After the vortex signal light completely transmits through the second polarization beam splitter 8, the vortex signal light vertically irradiates on the rotating body 10 to be tested through the quarter-wave plate 9, the vortex light is reflected by the rotating body 10 to be tested and passes through the quarter-wave plate 9 again, the polarization direction of the vortex optical rotation can rotate for 90 degrees relative to the initial vortex optical rotation, namely, the P polarized light is converted into the S polarized light, and when the S polarized vortex light irradiates on the second polarization beam splitter 8 again, the S polarized vortex light can be totally reflected.

An optical rotation sheet 11 is arranged between the first polarization beam splitter 5 and the second polarization beam splitter 8, and a polarizing sheet 12 is arranged between the second polarization beam splitter 8 and the beam splitter prism 13. The reference light formed by the reflection of the laser by the first polarization beam splitter 5 is S-polarized light, the S-polarized light is rotated by 90 ° by the optical rotation plate 11 and becomes P-polarized light, and the P-polarized light is also completely transmitted when being irradiated on the second polarization beam splitter 9.

The reference light completely transmitted by the second polarization beam splitter 8 and the vortex signal light reflected by the reference light are converged into a light beam, and the signal light and the reference light with mutually perpendicular polarization directions cannot interfere because the reference light converged into the light beam is P-polarized light and the signal light is S-polarized light. The signal light and the reference light are converged into one path of light beam and then irradiated on the polarizing plate 12, the polarizing plate 12 enables the polarization directions of the signal light and the reference light to be consistent, and the signal light with the consistent polarization direction interferes with the reference light. In order to optimize the contrast of the interference fringes, under the condition that the light intensities of the reference light transmitted by the second polarization beam splitter 8 and the signal light reflected by the reference light are equal, the polarization direction of the signal light and the polarization direction of the reference light are both rotated by 45 ° by the polarizer 12, so that the vibration directions of the signal light and the reference light are consistent and the light intensities are equal, and the optimal interference effect is obtained.

The signal light and the reference light are subjected to heterodyne interference and then irradiate on the beam splitting prism 13, the reflected light of the interference light beam irradiating on the beam splitting prism 13 is irradiated on the first photoelectric detector 16 after being converged by the first converging lens 14, the transmitted light is irradiated on the second photoelectric detector 17 after being converged by the second converging lens 15, and in order to ensure that interference light signals obtained by the first photoelectric detector 16 and the second photoelectric detector 17 are completely the same, the beam splitting ratio of the beam splitting prism 13 is 1: 1. In this way, the difference frequency signals detected by the first photodetector 16 and the second photodetector 17 are equal in amplitude and in phase, and random noise in the signals can be filtered by using an inverse phase subtraction method to obtain a precise difference frequency signal.

If the number of angular quanta of the spiral phase plate is l, and a difference frequency signal obtained after random noise is filtered by the first photodetector 16 and the second photodetector 17 is Δ f, then the following conditions are satisfied:

from equation (1):

wherein l is the angular quantum number of the spiral phase plate, and Δ f is the frequency of the difference frequency signal measured by the detector.