阅读说明：本技术 一种基于aotf的大口径平行单色偏振可调光源系统 (Large-caliber parallel monochromatic polarization adjustable light source system based on AOTF ) 是由 李占峰 王淑荣 黄煜 林冠宇 于 2019-10-17 设计创作，主要内容包括：本发明公开了一种基于AOTF的大口径平行单色偏振可调光源系统,属于偏振光学技术领域,首先通过光源发出稳定的连续谱光信号,经过平行光管产生均匀平行光束,入射到声光可调滤光器的入光端面,再通过改变换能器上射频驱动信号的频率,使得声光可调滤光器输出的+1级光束为目标波长的垂直偏振光,再通过声光可调滤光器后端的无偏扩束系统,将声光可调滤光器输出小口径的单色偏振光转换为大口径的单色偏振光。本发明在保证光谱分辨率较高的情况下,实现了大口径单色偏振光的输出,不但能提高光谱偏振遥感器的偏振定标精度,还可实现反射镜、光栅等核心偏振敏感元件的偏振特性测试,为设计和分析整机偏振偏特性分布提供了基础数据。(The invention discloses a large-caliber parallel monochromatic polarization adjustable light source system based on AOTF, which belongs to the technical field of polarization optics, and comprises the steps of firstly, sending a stable continuous spectrum light signal by a light source, generating uniform parallel light beams by a collimator, enabling the uniform parallel light beams to enter the light inlet end face of an acousto-optic adjustable filter, enabling a + 1-grade light beam output by the acousto-optic adjustable filter to be vertical polarized light with target wavelength by changing the frequency of a radio frequency driving signal on a transducer, and converting the monochromatic polarized light output by the acousto-optic adjustable filter into large-caliber monochromatic polarized light by a non-biased beam expanding system at the rear end of the acousto-optic adjustable filter. The invention realizes the output of large-aperture monochromatic polarized light under the condition of ensuring higher spectral resolution, not only can improve the polarization calibration precision of the spectral polarization remote sensor, but also can realize the polarization characteristic test of core polarization sensitive elements such as a reflector, a grating and the like, and provides basic data for designing and analyzing the polarization characteristic distribution of the whole machine.)

1. A large-aperture parallel monochromatic polarization adjustable light source system based on AOTF is characterized in that a light source emits stable continuous spectrum light signals, uniform parallel light beams are generated through a collimator and enter the light entrance end face of an acousto-optic adjustable filter, the frequency of a radio frequency driving signal on a transducer is changed, so that + 1-level light beams output by the acousto-optic adjustable filter are vertical polarized light with target wavelength, and the monochromatic polarized light with a small aperture output by the acousto-optic adjustable filter is converted into the monochromatic polarized light with a large aperture through a non-biased beam expanding system at the rear end of the acousto-optic adjustable filter.

2. The AOTF-based large-aperture parallel monochromatic polarization tunable light source system according to claim 1, wherein the light source is a 1000-watt halogen tungsten lamp source with output light signal stability better than 0.2%/hour.

3. The AOTF-based large aperture parallel monochromatic polarization tunable light source system according to claim 1, wherein the light source is located at the focal point of the collimator.

4. The AOTF-based large aperture parallel monochromatic polarization tunable light source system according to claim 1, wherein the divergence angle of the parallel light beams generated by the light source through the collimator is less than 0.02 °.

5. The AOTF-based large-aperture parallel monochromatic polarization tunable light source system according to claim 1, wherein the aperture of the collimated light beam output by the collimator is 12 mm.

6. The AOTF-based parallel large-aperture monochromatic polarization tunable light source system according to claim 1, wherein the clear aperture of the acousto-optic tunable filter is 10 mm.

7. The AOTF-based parallel large-aperture monochromatic polarization tunable light source system according to claim 1, wherein the angle between the incident direction of the parallel light beam and the normal of the light incident end surface of the acousto-optic tunable filter is 2 ° to 5 °.

8. The AOTF-based parallel large-aperture monochromatic polarization tunable light source system according to claim 1, wherein the acousto-optic tunable filter and the RF driver are installed on a circular turntable with a center light passing through, and the frequency of the RF driver is changed by rotating the angle of the circular turntable, so as to change the polarization direction of the output monochromatic polarized light.

9. The AOTF-based parallel large-aperture monochromatic polarization tunable light source system according to claim 1, wherein the unbiased beam expanding system consists of two confocal spherical lenses and a field stop is placed on the confocal plane to eliminate the 0 th order beam and the-1 st order beam from the AOTF filter.

10. The AOTF-based large-aperture parallel monochromatic polarization tunable light source system according to claim 9, wherein the two confocal spherical lenses include a focusing lens and a collimating lens, the + 1-order monochromatic polarized light, the 0-order polychromatic light and the-1-order monochromatic polarized light outputted from the acousto-optic tunable filter are irradiated onto the focusing lens, the three light beams are distributed and focused on the focal plane of the lens, the + 1-order monochromatic polarized light is focused on the focal point, the field stop blocks the 0-order polychromatic light and the-1-order monochromatic polarized light from entering the subsequent light path, the + 1-order monochromatic polarized light is incident on the surface of the collimating lens through the field stop, and the large-aperture monochromatic polarized parallel light beam is outputted through the collimating lens, wherein the focal length ratio of the collimating lens to the focusing lens is 8: 1.

Technical Field

The invention relates to the technical field of polarized optics, in particular to an AOTF-based large-caliber parallel monochromatic polarization adjustable light source system.

Background

Polarization is an inherent property of light waves. Light waves directly emitted by a general natural light source (such as the sun) are unpolarized, but are reflected, scattered or refracted by the surfaces of media such as molecules, particles and objects to form polarized light in different states, and the states of the polarized light contain a large amount of information representing the physical states and chemical properties of the media. Therefore, the remote sensing of the polarization spectrum has a wide application prospect in the fields of earth environment monitoring, military reconnaissance, material characteristic research, astronomy research, polarization navigation and the like, and the remote sensing research of the polarization spectrum has become a hot spot in recent years.

With the continuous improvement of the requirement of the remote sensing quantification precision of the polarization spectrum, the polarization calibration of the remote sensor of the polarization spectrum is gradually emphasized. The core device of polarization scaling is a polarized light source with known and adjustable polarization state. And (3) utilizing the light with known polarization degree output by the polarized light source to be incident into the polarization remote sensor to obtain the polarization response of the polarization remote sensor under different polarization states, and finishing the polarization calibration. Therefore, the polarized light source system determines the polarization calibration accuracy of the remote polarization sensor to a certain extent.

The polarized light source commonly used in the polarization calibration at present consists of a white light source, an integrating sphere, a beam expander collimation system and a polarization regulator. The polarization regulator comprises a 360-degree circular turntable and a linear polarizer. Types of linear polarizers are mainly sheet stack polarizers, metal wire grid polarizers and prism polarizers. The common polarized light source outputs polychromatic polarized light, cannot output monochromatic polarized light, can only carry out monochromatic polarization calibration after light splitting through a light splitting system of a calibrated polarization remote sensor, and cannot realize element-level polarization characteristic calibration. For the polarization remote sensor of the optical filter light splitting, a certain monochromatic polarization calibration error can be introduced due to the large bandwidth of the optical filter. The aperture of the polarized light output by the prism polarizer is generally less than 30mm, and the polarization characteristic test of a large-aperture spectrometer system cannot be met.

Disclosure of Invention

Aiming at the technical problems, the invention provides a large-caliber parallel monochromatic polarization adjustable light source system based on AOTF, which adopts an acousto-optic adjustable filter (AOTF) as a core device and can simultaneously realize high-resolution light splitting and high-precision polarizing functions. The problem that the existing polarized light source cannot output monochromatic polarized light or output polarized monochromatic bandwidth is large is solved. On the premise of ensuring that the polarization degree is not changed, a non-polarized beam expanding system is added behind an acousto-optic tunable filter (AOTF), so that the output of large-aperture monochromatic polarized light is realized, and the problem of aperture limitation of the existing acousto-optic tunable filter (AOTF) is solved. The large-aperture monochromatic polarization adjustable light source system realizes the output of large-aperture monochromatic polarized light under the condition of ensuring higher spectral resolution, not only can improve the polarization calibration precision of a spectral polarization remote sensor, but also can realize the polarization characteristic test of core polarization sensitive elements such as a reflector, a grating and the like, and provides basic data for designing and analyzing the polarization characteristic distribution of the whole machine.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the invention provides a large-aperture parallel monochromatic polarization adjustable light source system based on AOTF, which comprises the steps of firstly, sending a stable continuous spectrum light signal by a light source, generating uniform parallel light beams by a collimator, making the uniform parallel light beams enter the light-in end face of an acousto-optic adjustable filter, changing the frequency of a radio frequency driving signal on a transducer to enable + 1-grade light beams output by the acousto-optic adjustable filter to be vertical polarized light with target wavelength, and converting the monochromatic polarized light with small aperture output by the acousto-optic adjustable filter into the monochromatic polarized light with large aperture by a non-polarized beam expanding system at the rear end of the acousto-optic adjustable filter.

Furthermore, the light source is a 1000-watt halogen tungsten lamp light source with output light signal stability superior to 0.2%/hour.

Further, the light source is located at the focal point of the collimator.

Further, the divergence angle of the parallel light beams generated by the light source through the parallel light pipe is less than 0.02 degree.

Further, the aperture of the collimator for outputting the parallel light beam is 12 mm.

Further, the clear aperture of the acousto-optic tunable filter is 10 mm.

Furthermore, the included angle between the incident direction of the parallel light beams and the normal of the light incident end surface of the acousto-optic tunable filter is 2-5 degrees.

Furthermore, the acousto-optic tunable filter and the radio frequency driver are mounted on a circular turntable with a light passing center, and the frequency of the radio frequency driver is changed by rotating the angle of the circular turntable, so that the change of the polarization direction of the output monochromatic polarized light is realized.

Furthermore, the unbiased beam expanding system consists of two confocal spherical lenses, and a field stop is arranged on a confocal surface so as to eliminate the 0-order light beam and the-1-order light beam output by the acousto-optic tunable filter.

Further, the two confocal spherical lenses comprise a focusing lens and a collimating lens, wherein + 1-level monochromatic polarized light, 0-level polychromatic light and-1-level monochromatic polarized light output by the acousto-optic tunable filter are irradiated onto the focusing lens, the three light beams are distributed and focused on a focal plane of the lens, the + 1-level monochromatic polarized light is focused on a focal point, the field diaphragm blocks the 0-level polychromatic light and the-1-level monochromatic polarized light from entering a subsequent light path, the + 1-level monochromatic polarized light is incident on the surface of the collimating lens through the field diaphragm, a large-caliber monochromatic polarized parallel light beam is output through the collimating lens, and the focal length ratio of the collimating lens to the focusing lens is 8: 1.

Compared with the prior art, the invention has the technical effects that:

the large-aperture parallel monochromatic polarization adjustable light source system based on the AOTF provided by the invention overcomes the defect that the existing polarized light source system cannot output monochromatic polarized light, and realizes light splitting and polarization by using the acousto-optic adjustable filter as a core device, thereby obtaining monochromatic polarized light beams. Because the general angle of the light-passing aperture of the acousto-optic tunable filter is small, a non-polarized beam expanding system is added after the acousto-optic tunable filter outputs, the effective aperture of outputting monochromatic polarization parallel beams is increased, and the application range of the monochromatic polarization light source system is expanded. In addition, the polarization direction is adjustable by adding the circular rotary table, the polarization characteristic test requirements of the spectrometer complete machine and core polarization sensitive elements such as a reflector and a grating are met, the polarization characteristic test system is simplified, and the polarization characteristic test efficiency is improved.

Drawings

In order to more clearly illustrate the embodiments of the present application or technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings can be obtained by those skilled in the art according to the drawings.

FIG. 1 is a light path diagram of a large-aperture parallel monochromatic polarization tunable light source system based on AOTF.

Description of reference numerals:

1. a light source; 2. a collimator; 3. an acousto-optic tunable filter; 4. driving by radio frequency; 5. (ii) a 6. (ii) a 7. (ii) a 8. In that respect

Detailed Description

In order to make the technical solutions of the present invention better understood, those skilled in the art will now describe the present invention in further detail with reference to the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in figure 1, a stable continuous spectrum light signal is emitted by a light source 1, a uniform parallel light beam is generated by a collimator 2 and enters the light-in end face of an acousto-optic tunable filter 3, the frequency of a radio frequency drive 4 signal on a transducer is changed, so that a + 1-level light beam output by the acousto-optic tunable filter 3 is vertical polarized light with a target wavelength, and the small-caliber monochromatic polarized light output by the acousto-optic tunable filter is converted into large-caliber monochromatic polarized light by a non-polarized beam expanding system at the rear end of the acousto-optic tunable filter 3.

Specifically, in order to cover ultraviolet, visible and near infrared bands, the light source 1 is a high-intensity and high-stability light source, for example, a 1000 w halogen tungsten lamp light source with output light signal stability better than 0.2%/h. The light source 1 is located at the focal point of the collimator. The divergence angle of the parallel light beams generated by the light source 1 through the collimator 2 is less than 0.02 degree. The collimator 2 collimates the light emitted from the halogen tungsten lamp on the focus into parallel beams, and the aperture of the output parallel beams is 12 mm. The parallel light beams are incident on the light incident end face of the acousto-optic tunable filter 3, the clear aperture of the acousto-optic tunable filter 3 is 10mm, and the acousto-optic tunable filter 3 simultaneously plays roles in light splitting and polarization, so that the output light beams are changed into monochromatic polarized light beams.

In order to ensure that the +1 monochromatic polarized light beam output by the acousto-optic tunable filter keeps horizontal, the incident direction of the parallel light beam and the normal of the light incident end face of the acousto-optic tunable filter 3 have a certain included angle, and the included angle is preferably 2 to 5 degrees.

The parallel light beams are incident into the acousto-optic tunable filter to be diffracted, and + 1-order monochromatic polarized light, 0-order polychromatic light and-1-order monochromatic polarized light are output. In order to change the polarization direction of the output light beam and obtain monochromatic polarized light with different polarization directions, the acousto-optic tunable filter 3 and the radio frequency driver 4 are installed on a circular turntable with a light passing center, wherein the radio frequency driver has the function of enabling the acousto-optic tunable filter to output monochromatic polarized light with different wavelengths by changing the frequency of the radio frequency driving system. The circular turntable has the function of driving the acousto-optic tunable filter to rotate, so that the acousto-optic tunable filter outputs monochromatic polarized light in different polarization directions. The frequency of the radio frequency drive is changed by rotating the angle of the circular turntable, so that the change of the polarization direction of the output monochromatic polarized light is realized. The circular turntable 5 can realize 360-degree rotation, and the rotation angle precision is better than 0.05 degrees. And a proper radio frequency driving frequency adjusting range is set, so that the output monochromatic light wavelength can cover ultraviolet, visible and near-infrared bands.

Furthermore, the unbiased beam expanding system consists of two confocal spherical lenses, and a field diaphragm 7 is arranged on a confocal plane to eliminate the 0-level light beam and the-1-level light beam output by the acousto-optic tunable filter 3, so that the 0-level polychromatic light and the-1-level monochromatic polarized light beam are prevented from entering a subsequent system, and the polarization degree and the spectral resolution of the final output light beam are ensured.

Specifically, the two confocal spherical lenses comprise a focusing lens 6 and a collimating lens 8, the + 1-level monochromatic polarized light, the 0-level polychromatic light and the-1-level monochromatic polarized light output by the acousto-optic tunable filter 3 are irradiated onto the focusing lens 6, the three light beams are distributed and focused on a focal plane of the lens 6, the + 1-level monochromatic polarized light is focused on a focal point, and the field diaphragm 7 blocks the 0-level polychromatic light and the-1-level monochromatic polarized light from entering a subsequent light path, so that the polarization degree and the spectral resolution of the subsequent light beams are ensured. The + 1-level monochromatic polarization light beam enters the surface of a collimating lens 8 through a field diaphragm 7, a large-aperture monochromatic polarization parallel light beam is output through the collimating lens 8, and the focal length ratio of the collimating lens 8 to the focusing lens 6 is 8: 1. And the two lenses are confocal, so the aperture of the output beam of the lens 8 is 8 times of the aperture of the input beam of the lens 6. For example, the clear aperture of the acousto-optic tunable filter 3 is 10mm, so the aperture of the lens 8 outputting the monochromatic polarization parallel light beam can reach 80mm, and the use requirements of most spectrometers and optical elements can be met.

Therefore, the system can obtain large-aperture monochromatic polarized parallel light beams, the polarization direction is adjustable, and the defect that the existing polarized light source system cannot output monochromatic polarized light is overcome.

While certain exemplary embodiments of the present invention have been described above by way of illustration only, it will be apparent to those of ordinary skill in the art that the described embodiments may be modified in various different ways without departing from the spirit and scope of the invention. Accordingly, the drawings and description are illustrative in nature and should not be construed as limiting the scope of the invention.