CN214224366U

CN214224366U - Michelson interference type far infrared light polarization state conversion device

Info

Publication number: CN214224366U
Application number: CN202023086001.2U
Authority: CN
Inventors: 曹俊诚
Original assignee: Jiangxi Wanjun Photoelectric Co ltd
Current assignee: Jiangxi Wanjun Photoelectric Co ltd
Priority date: 2020-12-21
Filing date: 2020-12-21
Publication date: 2021-09-17
Anticipated expiration: 2030-12-21

Abstract

The utility model belongs to the technical field of far infrared laser, specifically speaking is a conversion equipment of michelson interference formula far infrared light polarization state, include: the device comprises a first linear polarizer, a movable mirror, a fixed mirror, a second linear polarizer, a lens and a detector. The utility model provides a far-infrared polarization conversion device can realize that linearly polarized light arrives the periodic regulation and the conversion of nearly circular polarized light again, and it is wide to have the working wavelength scope, and polarization conversion effect advantage such as good compares with traditional 45 degrees incident ray polarization piece modes, the utility model discloses utilize michelson's interference principle, can adjust the optical path difference that two bundles of meeting laser wantonly, broken through polarization conversion and accommodation process and received the restriction of plane mirror with the linear polarization piece distance, reduced the degree of difficulty of conversion and regulation, realized the conversion and the regulation of wideer wavelength range far-infrared polarization state, simultaneously the utility model discloses can also make two bundles of meeting laser coincidence completely, improved the SNR that closes a laser polarization state.

Description

Michelson interference type far infrared light polarization state conversion device

Technical Field

The utility model belongs to the technical field of far infrared laser, specifically speaking is a conversion equipment of michelson interference formula far infrared polarization state.

Background

Polarization characteristics are important parameters that describe the temporal and spatial variation of the far infrared optical electric field component, in addition to radiation frequency, power and beam quality. For example, in imaging applications, the polarization state of electromagnetic radiation changes with the form of the surface of a target object, and after a corresponding polarization detection means is added, the combined detection of the polarization state and the amplitude of the electromagnetic radiation in the imaging process can be realized, so-called holographic imaging is realized. Therefore, the utilization and detection of the polarization state play an important role in the application of electromagnetic radiation, the polarization conversion technology of far infrared light is developed, the application advantages of the electromagnetic wave frequency band can be improved, and different application effects can be obtained.

However, in the far infrared band, especially in the band above 30 microns, the means for generating electromagnetic radiation is relatively lacking, and most of the currently generated effective radiation is mainly in the linear polarization state, and is greatly limited in practical application. Therefore, it is of great significance to develop a means for realizing polarization state conversion of far infrared light to meet the practical application needs of the frequency band. The existing polarization conversion means mainly starts from the materials and microstructures of the converter, and realizes the change of the polarization state of emergent laser by designing the adjustment effect on the phase of incident laser. However, the radiation wavelength range of the above-mentioned polarization conversion method is small, and a polarization converter with a determined design structure and material can only realize the polarization conversion function within a certain wavelength range, and when the method is applied to multi-wavelength electromagnetic radiation, a plurality of polarization converters need to be configured, which increases the complexity of the system. In order to simplify the application system, an ultra-wide spectrum far infrared light polarization converter is proposed, wherein incident polarized light, a linear polarizer and a plane reflector form an incident angle of 45 degrees at the same time, and a good polarization conversion effect is obtained. However, due to the limitation of the incident angle of 45 degrees, the plane mirror for adjusting the polarization state must be very close to the off-line polarizer, usually within the distance between two wavelengths, to ensure that two beams of light forming interference can be well overlapped, when the plane mirror is more than two wavelengths away from the linear polarizer, due to the existence of the incident angle of 45 degrees, the overlapping area of the two beams of laser light after being overlapped becomes small, so that the polarization state of the combined laser light is not pure, the polarization conversion effect is poor, and this limitation has a great influence on the far infrared light with the wavelength less than 50 micrometers. Therefore, there is a need to develop a device and a method that can realize polarization conversion of wide-spectrum far-infrared light and can realize efficient conversion of polarization state of incident far-infrared light by adjusting a plane mirror in a large range.

SUMMERY OF THE UTILITY MODEL

In view of the foregoing prior art's shortcoming, the utility model aims at providing a conversion equipment of michelson interference formula far-infrared light polarization state and implementation method thereof, the light path principle that the device and implementation method utilized michelson to interfere, let two bundles of linear polarization light that movable mirror and fixed mirror reflect take place to interfere on the linear polarization piece that 45 degrees were placed, form the closed laser that polarization state driven mirror removed the regulation, two bundles of laser that this kind of mode formed have the characteristics of high coincidence, realized effective regulation and polarization conversion to wide-spectrum far-infrared polarized light from the principle, polarization imaging, the ellipsometry technique and the signal modulation for the far-infrared frequency channel provide a rather potential means.

In order to achieve the above objects and other related objects, the present invention provides a conversion device for michelson interference far-infrared light polarization state, which specifically comprises: the device comprises a first linear polarizer, a movable mirror, a fixed mirror, a second linear polarizer, a lens and a detector; the focuses of the first linear polaroid, the movable mirror, the second linear polaroid, the lens and the detector are on the same straight line, the movable mirror, the first linear polaroid, the second linear polaroid, the lens and the detector are sequentially arranged, and the fixed mirror is perpendicular to the first linear polaroid.

In the technical scheme, after far infrared parallel light passes through the first linear polarizer, one part of the light forms linearly polarized light to be reflected to the movable mirror, and the other part of the light forms linearly polarized light to reach the fixed mirror after passing through the first linear polarizer; linearly polarized light reflected by the movable mirror and linearly polarized light reflected by the fixed mirror are converged on the first linear polarizer to form combined interference light, and the combined interference light reaches the detector after passing through the second linear polarizer and the lens; the second linear polaroid is suitable for detecting the polarization characteristic of the combined beam interference light; the lens is used for converging the interference light after the beam combination, so that all the interference light is detected by the detector.

As a preferred scheme of the utility model, the working laser wavelength of the device covers 10 μm to 200 μm.

As a preferred scheme of the utility model, first line polaroid, second line polaroid are the polymer basement, and its surface of basement is the diffraction grating that the metal wire formed.

As a preferred scheme of the utility model, the fixed mirror and the movable mirror are both aluminum gold-plated surfaces;

as a preferred scheme of the utility model, the plane reflector is a gold-plated surface of a glass substrate.

As a preferred scheme of the utility model, the lens is a double-sided coated high-resistance silicon lens.

As a preferred scheme of the utility model, the detector is the heat detector.

The utility model has the advantages that: the utility model discloses a mode that Michelson interferes realizes far infrared's polarization conversion, both can realize that linearly polarized light arrives the periodic adjustment and the conversion of nearly circular polarized light again, utilize the moving mirror to the distance adjustable principle of first linear polarization piece and the high characteristics of beam overlap degree when the transmission is carried out through the linear polarization piece, broken through polarization state conversion and accommodation process and received the restriction of speculum and linear polarization piece distance, have than under the 45 degree incidence circumstances wideer working wavelength scope, from the effective regulation and the polarization conversion of realizing wideer far infrared polarized light wavelength range in principle, for the polarization imaging of far infrared frequency channel, ellipsometry technique and signal modulation provide a polarization regulation and control means of rather having the potentiality.

Drawings

Fig. 1 is a schematic diagram of the structure and the light path of the present invention.

Fig. 2 is a change of the polarization state of the combined laser beam along with the phase, which is realized by the device of the present invention, wherein the change of the phase is derived from the optical path difference formed by the moving of the movable mirror.

Fig. 3 is a schematic flow chart of a method for implementing the michelson interference far-infrared polarization conversion device of the present invention.

In the figure, 1-incident far infrared parallel light, 2-a first linear polarizer, 3-a moving mirror, 4-a fixed mirror, 5-a second linear polarizer, 6-a lens and 7-a detector.

Detailed Description

In order to deepen the understanding of the present invention, the present invention will be described in further detail with reference to the accompanying drawings and embodiments, which are only used for explaining the present invention and are not limited to the protection scope of the present invention.

Example (b): as shown in fig. 1, a conversion apparatus for michelson interferometric far-infrared polarization state at least includes a first linear polarizer 2, a movable mirror 3, a fixed mirror 4, a second linear polarizer 5, a lens 6 and a detector 7; after the far infrared parallel light 1 passes through the first linear polarizer 2, a part of light forms linearly polarized light and is reflected to the movable mirror 3, and the other part of light forms linearly polarized light after passing through the first linear polarizer 2 and reaches the fixed mirror 4; the linearly polarized light reflected by the movable mirror 3 and the linearly polarized light reflected by the fixed mirror 4 are converged on the first linear polarizer 2 to form combined interference light, and the combined interference light passes through the second linear polarizer 5 and the lens 6 and then reaches the detector 7; the second linear polarizer 5 is adapted to detect the polarization characteristic of the combined beam-back interference light; the lens 6 is used for converging the combined interference light, so that all the interference light is detected by the detector 7, and the measurement of the polarization state of the combined beam polarized light is finally completed by rotating the linear polarization angle of the second linear polarizer 5 and recording the signal amplitude on the detector 7.

The wavelength range of the far infrared parallel light is 10-200 μm by way of example, and preferably, in the present embodiment, the wavelength of the far infrared light is 64 μm, and the beam diameter is 12 mm.

For example, the first linear polarizer and the second linear polarizer are the same linear polarizer, both of which use high-density polyethylene material as a substrate, aluminum metal wires are deposited on the surface of the substrate, and the operating wavelength range of the linear polarizer covers 5-1000 μm, preferably, in this embodiment, the clear aperture of each linear polarizer is 76.2 mm.

By way of example, the movable mirror and the fixed mirror are gold-plated surfaces of glass substrates, the reflectivity of the far infrared light is greater than 98%, and preferably, in the embodiment, the diameters of the movable mirror and the fixed mirror are both 76.2 mm.

By way of example, the lens is a double-sided coated high-resistance silicon lens, and preferably, in the embodiment, the focal length of the lens is 150 mm, the diameter of the lens is 76.2 mm, the coating material is a polymer, and the coating thickness is 17 μm.

By way of example, the thermal detector is a pyroelectric detector, and preferably, in the present embodiment, the noise equivalent power in the far infrared band is less than 300 pW/hz0.5.

The utility model discloses utilize the michelson to interfere the principle among the device for through the far-infrared light of moving mirror 3 and the reflection of fixed mirror 4 completely coincide on second linear polarization piece 2, compare with 45 degrees incident modes, improved the overlapping rate of two bundles of light and closed a bundle interference effect.

Referring to fig. 3, the present invention further provides a method for implementing polarization conversion and adjustment of far-infrared light by using the conversion device of michelson interferometric far-infrared light polarization state as in the first embodiment, the method includes the steps of:

1) the first linear polarizer 2 converts the incident far infrared parallel light 1 into far infrared linearly polarized light with equal electric field component in horizontal and vertical directions, one part of the converted linearly polarized light is reflected and then reaches the movable mirror 3, and the other part of the linearly polarized light passes through the first linear polarizer 2 and then reaches the fixed mirror 4;

2) the linearly polarized light reaching the movable mirror 3 and the fixed mirror 4 is reflected and then reaches the first linear polarizer 2 to be converged, and after convergence, combined beam interference light is formed on the surface of the first linear polarizer 2;

3) the converged interference light passes through the second linear polarizer 5 and the lens 6 and then reaches the detector 7, and the second linear polarizer 5 and the detector 7 detect the converged interference light to obtain the actual polarization state of the interference light;

4) the distance between the movable mirror 3 and the first linear polarizer 2 is adjusted, the adjustment step length is 1/16 (namely 4 microns) of the wavelength of the incident far infrared parallel light 1, the phase changed in each step is pi/4 according to the relation that the optical path difference is equal to 2 times of the distance between the movable mirror 3 and the first linear polarizer 2, and the measurement results of the polarization states of the combined laser under the phase differences of 0, pi/2, pi, 3 pi/2 and 2 pi shown in the figure 2 respectively correspond to linearly polarized light, near circularly polarized light, linearly polarized light, near circularly polarized light and linearly polarized light. The phase of the polarized light reflected by the movable mirror 3 and reaching the surface of the first linear polarizer 2 forms periodic variation, and forms combined laser in different polarization states after interfering with linearly polarized light reflected by the fixed mirror 4, so that polarization conversion of incident polarized light is realized, and the polarization state of the combined laser in each state can be measured through the second linear polarizer 5 and the detector 7.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that the foregoing embodiments and descriptions are provided only to illustrate the principles of the present invention without departing from the spirit and scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A conversion equipment of Michelson interference far infrared polarization state, its characterized in that: the focus of the first linear polaroid, the movable mirror, the second linear polaroid, the lens and the detector are arranged on the same straight line in sequence, the movable mirror, the first linear polaroid, the second linear polaroid, the lens and the detector are arranged, and the fixed mirror is perpendicular to the first linear polaroid.

2. The device of claim 1, wherein the device comprises: the first linear polaroid and the second linear polaroid are both polymer substrates, and diffraction gratings formed by metal wires are arranged on the surfaces of the substrates.

3. The device of claim 1, wherein the device comprises: the fixed mirror and the movable mirror are both aluminum-plated gold surfaces.

4. The device of claim 1, wherein the device comprises: the lens is a high-resistance silicon lens with a double-sided coated film.

5. The device of claim 1, wherein the device comprises: the detector is a thermal detector.