CN-115993727-B - Parameter-controllable random structured light generating device and method

CN115993727BCN 115993727 BCN115993727 BCN 115993727BCN-115993727-B

Abstract

The invention discloses a parameter-controllable random structure light generating device and method, wherein a light beam emitted by a laser sequentially passes through a linear polarizing plate and a beam expander and then enters a beam splitter, the light beam reflected by the beam splitter is a first path of light beam, the first path of light beam enters a digital micro-mirror device loaded with a holographic plate for modulation, a second path of light beam is obtained after modulation, the second path of light beam is then incident into the beam splitter and then enters a common path interference system after transmission, the second path of light beam passes through a first lens in the common path interference system, positive and negative first-stage light spots are filtered out through a small aperture diaphragm at the focal plane of the first lens, and the positive and negative first-stage light spots are respectively combined into a random vector light beam through a second lens and a Langmuir grating after passing through two half-wave plates. The invention can accurately generate the random structure light beam, and compared with the traditional structure light beam, the invention can regulate and control the polarization degree and the space coherence degree of the generated random structure light beam.

Inventors

ZHU XINLEI
WU JIDONG
WANG FEI
YU JIAYI
CAI YANGJIAN

Assignees

山东师范大学

Dates

Publication Date: 20260508
Application Date: 20221118

Claims (7)

1. The random structure light generating device with controllable parameters is characterized by comprising a laser, a linear polarizing plate, a beam expander, a digital micro-mirror device loaded with a holographic plate, a beam splitter and a common-path interference system, wherein light beams emitted by the laser sequentially pass through the linear polarizing plate and the beam expander and then are incident to the beam splitter, light beams reflected by the beam splitter are first light beams, the first light beams enter the digital micro-mirror device loaded with the holographic plate to be modulated, a second light beam is obtained after modulation, the second light beam is incident to the beam splitter, and the second light beam is incident to the common-path interference system after transmission; The second path of light beam passes through the first lens, positive and negative first-order light spots are filtered out through the aperture diaphragm at the focal plane of the first lens, and the positive and negative first-order light spots are combined into random vector light beams through the second lens and the Langmuir grating after respectively passing through the two half-wave plates; the hologram loaded in the digital micromirror device is called a complex screen, and contains information of a beam pattern to be generated, including the amplitude and phase of the beam; The method comprises the steps that a holographic sheet is loaded, a digital micro mirror in a digital micro mirror device is divided into two complex screens, electric fields in two directions are regulated and controlled through the two complex screens respectively and independently, the complex screens contain polarization and space coherence of light beams to be generated, the two complex screens in the digital micro mirror device are utilized to modulate first light beams respectively, and the amplitude and the phase of the light beams on the two complex screens are regulated and controlled; The modulating process comprises the following steps: two complex screens And Expressed as a product Is an inverse fourier transform of (a), given by the formula: Wherein, the Is a zero-mean unit variance, circular complex Gaussian random number U, v are discrete space indexes, m, n are discrete space frequency indexes, lx and Ly are the physical sizes of the x and y direction discrete grids respectively, Φαα is a power spectral density function; Then And The cross-correlation of (c) is: To generate cross-correlation functions The random number is represented in the form: ; on the basis of definitely setting random numbers, a Monte Carlo method is adopted to synthesize a complex screen And A corresponding hologram is generated.
2. The parameter-controllable random structured light generating apparatus of claim 1, further comprising random structured light measuring means; The device comprises a third lens and a fourth lens which form an optical 4F system, a beam splitter, a linear polarizer, a quarter wave plate and a charge coupled device; After passing through a third lens and a fourth lens which form an optical 4F system, the random vector light beams obtained through the Rankine grating are incident into a beam splitter at the back focal plane of the fourth lens, the light beams transmitted by the beam splitter are third light beams, and the light beams reflected by the beam splitter are fourth light beams; the third path of light beam sequentially passes through the linear polaroid and the quarter wave plate to be incident into the charge coupled device, and the calculation is carried out through the recorded light beam to obtain the Stokes parameter of the light beam; The fourth beam is transmitted and reflected to the corresponding charge coupled device through the beam splitter, and the mutual interference function of the beams is measured and obtained according to Hanbury Brown-Twiss principle.
3. A parameter-controllable random structured light generating method implemented by a parameter-controllable random structured light generating device according to any one of claims 1-2, comprising the steps of: The method comprises the steps that a beam emitted by a laser sequentially passes through a linear polarizing plate and a beam expander and then enters a beam splitter, the beam reflected by the beam splitter is a first path of beam, the first path of beam enters a digital micro-mirror device loaded with a hologram for modulation, a second path of beam is obtained after modulation, the second path of beam is then incident into the beam splitter, and the second path of beam is transmitted and then enters a common path interference system; the second path of light beam passes through the first lens, positive and negative first-order light spots are filtered out through a small aperture diaphragm at the focal plane of the first lens, and the positive and negative first-order light spots respectively pass through two half-wave plates and then are combined into a random vector light beam through the second lens and the Langerhans grating.
4. A method of generating a parameter-controllable random structured light as claimed in claim 3, wherein the hologram loaded in the digital micromirror device is referred to as a complex screen, said hologram containing information of the beam pattern to be generated, including the amplitude and phase of the beam.
5. The method for generating random structured light with controllable parameters according to claim 4, wherein the digital micromirror device is divided into two complex screens by loading the hologram, electric fields in two directions are regulated and controlled by the two complex screens respectively and independently, the complex screens contain polarization and spatial coherence of light beams to be generated, the two complex screens in the digital micromirror device are utilized to modulate the first path of light beams respectively, and amplitude and phase of the light beams on the two complex screens are regulated and controlled.
6. A parameter-controllable random structured light generating method according to claim 5, wherein said modulating comprises: two complex screens And Expressed as a product Is an inverse fourier transform of (a), given by the formula: Wherein, the Is a zero-mean unit variance, circular complex Gaussian random number M, n are discrete space frequency indexes, lx and Ly are the physical sizes of the discrete grids in the x and y directions respectively, and Φαα is a power spectral density function; Then And The cross-correlation of (c) is: To generate cross-correlation functions The random number is represented in the form: ; on the basis of definitely setting random numbers, a Monte Carlo method is adopted to synthesize a complex screen And A corresponding hologram is generated.
7. A parameter-controllable random structured light generating method according to claim 3, further comprising: After passing through a third lens and a fourth lens which form an optical 4F system, the random vector light beams obtained through the Rankine grating are incident into a beam splitter at the back focal plane of the fourth lens, the light beams transmitted by the beam splitter are third light beams, and the light beams reflected by the beam splitter are fourth light beams; the third path of light beam sequentially passes through the linear polaroid and the quarter wave plate to be incident into the charge coupled device, and the calculation is carried out through the recorded light beam to obtain the Stokes parameter of the light beam; The fourth beam is transmitted and reflected to the corresponding charge coupled device through the beam splitter, and the mutual interference function of the beams is measured and obtained according to Hanbury Brown-Twiss principle.

Description

Parameter-controllable random structured light generating device and method Technical Field The invention relates to the technical field of optics, in particular to a random structure light generating device and method with controllable parameters. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. In recent years, structured light has been widely focused, and structured light has been widely used in information detection, optical imaging, optical capturing, and the like. For example, typical structured beams include vortex beams carrying helical phases, the phases with different topological charges forming infinite dimensions in the Hilbert space, thereby enabling a powerful carrier in high data rate communications, and vector beams having non-uniform spatial distribution in both complex fields and polarization, by modulating polarization, tightly focused vector beams will produce singular polarization topologies, thus yielding new optical applications, and various schemes for generating vector beams have been proposed so far. Although the operation of structured light is more and more mature at present, the development of new degrees of freedom of structured light has been an urgent pursuit in the field of optical technology, and the new degrees of freedom of structured light have profound effects on new applications. The existing research on generating the structural light beam can only generate a very limited type of random structural light beam, the spatial coherence and polarization state of the structural light cannot be accurately regulated and controlled, and random structural light with controllable all parameters and physical realizable characteristics is difficult to generate. Disclosure of Invention In order to solve the defects in the prior art, the invention provides a parameter-controllable random structure light generating device and method, which can accurately generate random structure light beams, and compared with the traditional structure light beams, the invention can regulate and control the polarization degree and the space coherence degree of the generated random structure light beams at the same time, provides a new opportunity for arbitrarily manipulating the polarization state of the internal structure light beams of the Poincare sphere, and has important application in free space optical communication and optical imaging. The first aspect provides a random structure light generating device with controllable parameters, which comprises a laser, a linear polarizing plate, a beam expander, a digital micro-mirror device loaded with a hologram, a beam splitter and a common-path interference system, wherein a light beam emitted by the laser sequentially passes through the linear polarizing plate and the beam expander and then enters the beam splitter, the light beam reflected by the beam splitter is a first path of light beam, the first path of light beam enters the digital micro-mirror device loaded with the hologram to be modulated, a second path of light beam is obtained after modulation, the second path of light beam enters the beam splitter again, and the light beam enters the common-path interference system after transmission; The common-path interference system comprises a first lens and a second lens which form an optical 4F system, an aperture diaphragm, two half-wave plates and a Langmuir grating, wherein the aperture diaphragm, the two half-wave plates and the Langmuir grating are positioned on focal planes of the two lenses and are sequentially arranged, the second path of light beam passes through the first lens, positive and negative first-order light spots are filtered out through the aperture diaphragm at the focal plane of the first lens, and the positive and negative first-order light spots are combined into random vector light beams through the second lens and the Langmuir grating after respectively passing through the two half-wave plates. Further technical proposal, the device also comprises a random structured light measuring device; The device comprises a third lens and a fourth lens which form an optical 4F system, a beam splitter, a linear polarizer, a quarter wave plate and a charge coupled device; After passing through a third lens and a fourth lens which form an optical 4F system, the random vector light beams obtained through the Rankine grating are incident into a beam splitter at the back focal plane of the fourth lens, the light beams transmitted by the beam splitter are third light beams, and the light beams reflected by the beam splitter are fourth light beams; the third path of light beam sequentially passes through the linear polaroid and the quarter wave plate to be incident into the charge coupled device, and the calculation is carried out through the recorded light beam to obtain the Stokes parameter of the light beam; The fourth beam is