Multi-slit interference device based on spatial light phase modulation

Abstract

The utility model discloses a multi-slit interference device based on spatial light phase modulation. The device belongs to the field of diffraction light field regulation and control and comprises a light source, a collimating lens, a first spectroscope, a phase-type spatial light modulator, a first projection system lens, a diaphragm, a second projection system lens, a digital micromirror, a second spectroscope, a camera and the like. According to the utility model, the spatial light modulator and the digital micromirror are controlled through software to modulate the phases and the shapes of the multiple slits respectively, and any phase type multiple slits are constructed; according to the phase-type multi-slit diffraction and interference theory provided by the utility model, the device can flexibly construct multiple slits and control the spatial form of interference fringes so as to generate a target light field with multiple purposes; the experimental device has the characteristics of modularization, small occupied volume and low assembly difficulty.

Description

Technical Field

[0001] The utility model belongs to the field of diffraction light field control, and relates to a multi-slit interferometer based on spatial light phase modulation; specifically, it relates to a multi-slit interferometer based on spatial light phase modulation, in which both phase distribution and spatial distribution are flexibly adjustable. Background Art

[0002] As an important element in the field of optics, multiple slits have always received extensive attention. At present, the research on multiple slits at home and abroad mainly focuses on basic theory, preparation technology, and its application in different fields. In terms of basic theory, researchers have continuously revealed its unique physical properties by deeply exploring the interference and diffraction phenomena of light waves in multiple slits. Previous studies have mainly focused on periodic multiple slits (gratings), such as transmission, reflection and blazed gratings, which can be widely used in spectral analysis, optical interference, optical communication, sensing and imaging and other fields. However, while periodic multiple slits are easy to design, they also limit the shape of the light field, and only parallel straight stripes can be obtained when no phase is added. Therefore, the utility model expands the research to non-periodic multiple slits, and innovatively designs a device that can conveniently perform phase and spatial modulation on non-periodic multiple slits, and summarizes the qualitative relationship between the spatial distribution of multiple slits and their initial phase distribution and interference patterns, which is helpful to expand the theoretical research and application of multiple slits. Utility Model Content

[0003] In view of the above problems, the purpose of the utility model is to expand the traditional multi-slit research and provide a new idea for modulating the interference pattern of multiple slits; in theory, it helps to study the changes in the shape of the diffracted light field caused by the spatial distribution of multiple slits and their initial phase distribution; in application, as a model device for multi-slit interference applications, combined with the independently developed phase modulation program, it can quickly and conveniently carry out light field control experiments, which is helpful to promote the research in multi-slit interference application fields such as laser engraving and information encryption.

[0004] The technical solution of the utility model is: a multi-slit interferometer based on spatial light phase modulation (a multi-slit interferometer based on spatial light phase modulation with flexible and adjustable phase distribution and spatial distribution) described in the utility model comprises a collimating lens, a beam splitter, a phase-type spatial light modulator, a projection system, a digital micromirror and a camera;

[0005] The beam splitter can transmit half of the light and reflect the other half of the light, and comprises a first beam splitter and a second beam splitter.

[0006] Furthermore, the projection system is arranged between the first beam splitter and the second beam splitter, and is composed of two lenses with equal focal lengths and an aperture.

[0007] Furthermore, the two equal focal length lenses include projection system lens 1 and projection system lens 2;

[0008] Among them, the distance between the reflective surface of the first beam splitter and the mirror surface of the projection system lens 1, the distance between the mirror surface of the projection system lens 1 and the aperture, the distance between the aperture and the mirror surface of the projection system lens 2, and the distance between the mirror surface of the projection system lens 2 and the second beam splitter are the lens focal lengths.

[0009] Furthermore, a light source is provided on one side of the collimating lens, the first beam splitter is provided on the other side of the collimating lens, and the phase-type spatial light modulator is provided on the other side of the first beam splitter;

[0010] The digital micromirror is arranged on one side of the second beam splitter, and the camera is arranged on the other side of the second beam splitter.

[0011] Furthermore, the light source is placed at the front focus of the collimating lens, passes through the collimating lens and forms parallel light behind the collimating lens; the parallel light passes through the first beam splitter and is reflected on the surface of the phase-type spatial light modulator, then is reflected by the first beam splitter, passes through the projection system, is reflected by the second beam splitter, then is reflected by the digital micromirror, and passes through the second beam splitter to form interference fringes on the camera.

[0012] Furthermore, when in working state, the digital micromirror and the phase-type spatial light modulator are connected to a computer, which is controlled by the computer to load the set images respectively, and the image of the phase-type spatial light modulator is projected onto the surface of the digital micromirror through the projection system for spatial modulation, and then interference is generated from the digital micromirror to the camera distance.

[0013] The beneficial effects of the utility model are as follows: 1. The utility model can conveniently change the shape of interference fringes and generate a target light field with multiple uses. It has the characteristics of modular experimental device, small occupied volume and low assembly difficulty; without replacing the multi-slit, the spatial light modulator and the digital micromirror can be controlled by software to modulate the phase and shape of the multi-slit respectively, construct any phase-type multi-slit, and simplify the experimental process; 2. The utility model can be used in the teaching field. As a university physics experimental teaching device, the phase can be modulated by the phase-type spatial light modulator to deepen students' understanding of the relationship between phase difference and optical path difference in interference experiments; the multi-slits are spatially modulated by digital micromirrors to control the spatial form of interference fringes, so that the distance and width of the interference slits can be changed more conveniently; more parameters in the theoretical teaching of interference experiments are reflected in this device. Through the interference experimental device provided by the utility model, students can more intuitively observe the generation and change process of interference phenomena, thereby deepening their understanding of the interference principle, and can design different experimental schemes according to their own interests and needs. Exploring different experimental phenomena effectively improves students' experimental interest and cultivates their innovative and practical abilities; 3. The utility model can be used in the field of information encryption. Through this device, an interference pattern similar to the shape of 26 English letters can be obtained. It has high application value in the field of text encryption communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the prior art;

[0015] Figure 2 It is a structural schematic diagram of the utility model;

[0016] In the figure: 11 is a light source, 12 is a collimating lens, 13 is an interference screen, and 14 is a receiving screen;

[0017] 1 is the light source, 2 is the collimating lens, 3 is the first beam splitter, 4 is the phase-type spatial light modulator, 5 is the projection system lens 1, 6 is the aperture, 7 is the projection system lens 2, 8 is the digital micromirror, 9 is the second beam splitter, and 10 is the camera. DETAILED DESCRIPTION

[0018] The specific technical scheme of the utility model is further described in detail below with reference to specific examples.

[0019] As shown in the figure, an interference experiment device based on a light modulator element described in the utility model includes a light source 1, a collimating lens 2, a first beam splitter 3, a phase-type spatial light modulator 4 (Spatial Light Modulator, SLM), a projection system, a second beam splitter 9, a digital micromirror 8 (Digital micromirror device, DMD) and a camera 10;

[0020] The beam splitter can transmit half of the light and reflect the other half;

[0021] The projection system is composed of two lenses with equal focal lengths (projection system lens 1 5 and projection system lens 2 7) and an aperture 6, wherein the distance between the reflective surface of the first beam splitter 3 and the mirror surface of the projection system lens 1 5, the distance between the mirror surface of the projection system lens 1 5 and the aperture 6, the distance between the aperture 6 and the mirror surface of the projection system lens 2 7, and the distance between the mirror surface of the projection system lens 2 7 and the second beam splitter 9 are the lens focal lengths.

[0022] The device provided by the utility model, when in working state, the digital micromirror 8 (DMD) and the phase-type spatial light modulator 4 (SLM) are controlled by a computer, and the set images are loaded respectively, and the image of the phase-type spatial light modulator 4 is projected onto the surface of the digital micromirror 8 through the projection system, and interference is generated from the digital micromirror 8 to the camera 10.

[0023] The diffraction and interference theory of phase-type multi-slits proposed by the utility model is that the distribution of interference fringes and phase difference of double slits is basically consistent; the multi-slit interference pattern can be approximately simplified to the superposition of interference patterns of all double slit combinations with smaller spacing.

[0024] The working principle of the utility model is as follows: an image is loaded into a phase-type spatial light modulator 4 and a digital micromirror 8 through a computer; the phase-type spatial light modulator 4 performs phase modulation on the collimated light source 1, so that the light irradiated on different pixel points of the phase-type spatial light modulator 4 is added with an initial phase modulated by the corresponding pixel point; the light with the initial phase is spatially modulated by the digital micromirror 8 to control the spatial form of the interference fringes; the light generates interference on the surface of the camera 10 and is displayed on the computer.

[0025] Comparative Example

[0026] See also Figure 1 , the device is a schematic diagram of an existing commonly used interference experimental device; the device includes a light source 11, a collimating lens 12, an interference screen 13 and a receiving screen 14; wherein the light source 11 is placed at the front focus of the collimating lens 12 and passes through the collimating lens 2 to form parallel light behind the lens; the parallel light passes through the interference screen 13 containing two light-transmitting slits and forms interference fringes on the receiving screen 14.

[0027] Example

[0028] See also Figure 2 , which is a schematic diagram of the utility model device. The device includes a light source 1, a collimating lens 2, a first beam splitter 3, a phase-type spatial light modulator 4, a projection system lens 1 5, an aperture 6, a projection system lens 2 7, a digital micromirror 8, a second beam splitter 9 and a camera 10, etc.;

[0029] Among them, the light source 1 is placed at the front focus of the collimating lens 2 and passes through the collimating lens 2 to form parallel light behind the lens; the parallel light passes through the first beam splitter 3 and is reflected on the surface of the phase-type spatial light modulator 4, is reflected by the first beam splitter 3, passes through the projection system (projection system lens 1 5, aperture 6, projection system lens 2 7), is reflected by the second beam splitter 9, is reflected by the digital micromirror 8, passes through the second beam splitter 9, and forms interference fringes on the camera 10.

[0030] Experimental procedures

[0031] Step 1: Light path construction:

[0032] Reference Figure 2 , build the optical path; install the optical elements in sequence according to the serial numbers in the figure. Taking into account the error caused by the difficulty of light strictly passing through the center of each element, each optical element is set on an optical platform. The three-dimensional coordinates and pitch angle of the optical element can be fine-tuned by adjusting the knob to reduce experimental errors.

[0033] Step 2: Image loading

[0034] The preset or customized images are loaded onto the phase-type spatial light modulator 4 and the digital micromirror 8 respectively on the computer through the Python-based graphical user interface (GUI) software developed in conjunction with the computer; both devices have the ability to load images through computer control, allowing users to adjust the image content according to experimental requirements.

[0035] Step 3: Image acquisition:

[0036] Light carries different initial phase and intensity information during propagation, causing interference on the camera surface. The result of the interference is manifested as specific interference fringes or images formed on the camera 10. The camera 10 transmits the captured interference image back to the computer for display and processing.

Claims

1. A multi-slit interferometer based on spatial light phase modulation, characterized in that: It comprises a collimating lens (2), a beam splitter, a phase-type spatial light modulator (4), a projection system, a digital micromirror (8) and a camera (10); The beam splitter can transmit half of the light and reflect the other half of the light, and comprises a first beam splitter (3) and a second beam splitter (9); A light source (1) is provided on one side of the collimating lens (2), the first beam splitter (3) is provided on the other side of the collimating lens (2), and the phase-type spatial light modulator (4) is provided on the other side of the first beam splitter (3); The digital micromirror (8) is arranged on one side of the second beam splitter (9), and the camera (10) is arranged on the other side of the second beam splitter (9).

2. A multi-slit interferometer based on spatial light phase modulation according to claim 1, characterized in that: The projection system is arranged between the first beam splitter (3) and the second beam splitter (9), and is composed of two lenses of equal focal length and an aperture (6); The two equal focal length lenses include projection system lens 1 (5) and projection system lens 2 (7); The distance between the reflection surface of the first beam splitter (3) and the mirror surface of the projection system lens 1 (5), the distance between the mirror surface of the projection system lens 1 (5) and the diaphragm (6), the distance between the diaphragm (6) and the mirror surface of the projection system lens 2 (7), and the distance between the mirror surface of the projection system lens 2 (7) and the second beam splitter (9) are the lens focal lengths.

3. The multi-slit interferometer based on spatial light phase modulation according to claim 1, characterized in that: The light source (1) is placed at the front focus of the collimating lens (2), passes through the collimating lens (2) and forms parallel light behind the collimating lens (2); the parallel light passes through a first beam splitter (3), is reflected on the surface of a phase-type spatial light modulator (4), is then reflected by the first beam splitter (3), passes through a projection system, is reflected by a second beam splitter (9), is then reflected by a digital micromirror (8), passes through the second beam splitter (9), and forms interference fringes on a camera (10).

4. The multi-slit interferometer based on spatial light phase modulation according to claim 1, characterized in that: When in working state, the digital micromirror (8) and the phase-type spatial light modulator (4) are connected to a computer, which is controlled by the computer to load set images respectively, and the image of the phase-type spatial light modulator (4) is projected onto the surface of the digital micromirror (8) through a projection system to perform spatial modulation, and then interference is generated at the distance from the digital micromirror (8) to the camera (10).

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