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CN-122015645-A - Ultra-high-speed dynamic light projection method and system based on laser array

CN122015645ACN 122015645 ACN122015645 ACN 122015645ACN-122015645-A

Abstract

The invention relates to the technical field of structured light projection, in particular to an ultra-high-speed dynamic light projection method and system based on a laser array, wherein the method comprises the steps of constructing a plurality of paths of coherent light sources, carrying out beam combination treatment on outgoing lasers of the plurality of paths of coherent light sources, and forming combined lasers propagating along the same optical axis along a second direction; the method comprises the steps of utilizing a phase modulator to apply controllable phase modulation to laser beams to generate modulated laser beams with different phase states, enabling the modulated laser beams to be incident to a diffraction optical element, enabling the incident modulated laser beams to be diffracted along a second direction to form periodic structure light stripes, enabling the structure light stripes to generate equivalent continuous or stepping phase translation in the second direction by controlling the phase modulator to switch between different preset phase states, enabling the structure light stripes to be projected to the surface of a measured object, and synchronously collecting structure light images modulated by the surface of the object under different phase states.

Inventors

  • HU XIAOWEI
  • YANG XINJIE

Assignees

  • 苏州朗伯威智造科技有限公司

Dates

Publication Date
20260512
Application Date
20260206

Claims (9)

  1. 1. The ultra-high-speed dynamic light projection method based on the laser array is characterized by comprising the following steps of: Combining the outgoing laser beams of the multiple coherent light sources to form combined laser beams propagating along the same optical axis along a second direction, wherein the second direction is perpendicular to the first direction; Applying controllable phase modulation to the combined laser by using a phase modulator to generate modulated laser with different phase states; The modulated laser is incident to a diffraction optical element, and the incident modulated laser is diffracted along a second direction to form periodic structure light stripes according to a grating structure of the diffraction optical element with specific phase distribution; The phase modulator is controlled to be switched between different preset phase states, so that the structural light fringes generate equivalent continuous or stepping phase translation in a second direction; And projecting the phase-shifted structured light stripes to the surface of the object to be measured, and synchronously collecting structured light images modulated by the surface of the object in different phase states.
  2. 2. The ultra-high-speed dynamic light projection method based on a laser array according to claim 1, wherein the step-by-step beam combination processing is performed on the outgoing laser beams of the multiple coherent light sources by using a polarization beam splitter, and the method is specifically as follows: the polarization direction of partial emergent laser light in the laser array is rotationally controlled through the half wave plate, so that the polarization states of the emergent laser light output by adjacent lasers are orthogonal; The method comprises the steps that a first path of emergent laser is incident to a first polarization spectroscope from the side face, a second path of emergent laser is incident to the first polarization spectroscope from the front face, and the first polarization spectroscope outputs first-level combined laser; taking the first-stage combined laser as a light source, entering a second polarization spectroscope from the side surface, entering a third-way emergent laser from the front surface to the second polarization spectroscope, and outputting the second-stage combined laser by the second polarization spectroscope; and sequentially combining the beams step by step until the final polarization spectroscope outputs the combined laser beams of all the coherent light sources.
  3. 3. The ultra-high speed dynamic light projection method based on laser array according to claim 1, wherein the diffractive optical element is designed to simultaneously generate at least two periodic structured light stripe patterns having different spatial frequencies, and the periodic values corresponding to the different spatial frequencies are mutually identical.
  4. 4. The laser array-based ultra-high speed dynamic light projection method according to claim 1, wherein the phase modulator is controlled to switch between different preset phase states by a preset N-step phase sequence.
  5. 5. The ultra-high-speed dynamic light projection method based on the laser array according to claim 1, further comprising the step of obtaining the absolute phase of the measured object by combining structured light images of the surface of the measured object with at least two different periodic stripes and performing image processing calculation.
  6. 6. The ultra-high-speed dynamic light projection method based on a laser array according to claim 5, wherein the image processing calculation is performed to obtain the absolute phase of the measured object, and the operations specifically include: Each image acquired by the imaging acquisition module simultaneously contains two sets of stripe information with different periods, and the intensity information of the two sets of stripes is separated from a single image through a frequency domain filtering or demodulation algorithm; independently calculating wrapping phase maps phi 1 and phi 2 corresponding to the period P1 and the period P2 respectively for the image groups acquired by each phase shift sequence; The unambiguous absolute phase map Φ abs over a larger synthetic period is directly calculated from Φ 1 and Φ 2 using a dual frequency phase unwrapping algorithm.
  7. 7. The ultra-high-speed dynamic light projection system based on the laser array for realizing the ultra-high-speed dynamic light projection method based on the laser array according to claim 1 is characterized by comprising a system controller, and a laser array, a beam combining optical component, a phase modulator, a diffraction optical element, a projection lens group and an imaging acquisition module which are sequentially arranged along an optical axis, wherein the system controller is respectively and electrically connected with the laser array, the phase modulator and the imaging acquisition module; the system controller is used for controlling the phase switching sequence of the phase modulator, synchronously triggering the structured light images of the detected object collected by the program collecting module under different phase states, obtaining the structured light images collected by the imaging collecting module, and carrying out image processing to calculate the absolute phase of the detected object; a laser array for generating multiple independent laser beams; the beam combining optical component is used for combining the multiple paths of laser beams into coaxial laser beams; The phase modulator is used for applying phase modulation to the coaxial laser emitted by the beam combining optical component; a diffraction optical element for diffracting the phase-modulated light beam in a specific direction to form a periodic structured light stripe; the projection lens group is arranged behind the light path of the diffraction optical element and is used for projecting the structural light stripes to the surface of the object to be measured; The imaging acquisition module is used for acquiring the structured light images of the surface of the object to be measured under different phase modulation states and transmitting the acquired structured light images to the system controller for image processing.
  8. 8. The ultra-high speed dynamic light projection system based on a laser array according to claim 7, wherein the beam combining optical component adopts a multi-stage polarization beam combining structure, and the multi-stage polarization beam combining structure comprises a plurality of polarization beam splitting prisms.
  9. 9. The laser array based ultra high speed dynamic light projection system of claim 7, wherein the phase modulator is an acousto-optic modulator and/or an electro-optic modulator.

Description

Ultra-high-speed dynamic light projection method and system based on laser array Technical Field The invention relates to the technical field of structured light projection, in particular to an ultra-high-speed dynamic light projection method and system based on a laser array. Background In the fields of industrial three-dimensional measurement, machine vision, on-line detection and the like, structured light projection technology is widely applied due to the high precision and non-contact characteristics. Currently, the mainstream structured light projection system mainly adopts a digital micromirror Device (DLP) or a liquid crystal silicon device (LCOS) structured light projection system. These systems acquire the three-dimensional topography of an object by time-sequential loading of different gray scale fringe patterns in combination with a phase shift algorithm. However, the prior art suffers from the following significant drawbacks: Phase shift speed bottleneck-DLP/LCOS systems rely on physical flipping or state change of the micromirror or liquid crystal cell to switch patterns, the refresh rate of which is limited by the response time of the device itself. In order to generate high-quality sine fringes, multi-frame image synthesis is generally required, so that the effective three-dimensional frame rate is greatly reduced, and the real-time measurement requirement of a high-speed moving object is difficult to meet. The light energy utilization rate is low, a large amount of light energy is deflected to a light trap by a micromirror to be lost in a DLP system, the LCOS system has polarization dependent absorption and reflection loss, the overall light efficiency is low, and a high-power light source is often required to be used for obtaining enough signal-to-noise ratio, so that the problems of heat dissipation, power consumption and service life are caused. System stability and complexity micro-electromechanical system (MEMS) based DLP light engines suffer from thermal drift and long term reliability problems at high speed operation. Meanwhile, in order to correct projection nonlinearity and gamma effect, complex calibration and compensation algorithms are required, and correction parameters are easy to drift along with time and environmental changes. The multi-period projection has low efficiency, and a plurality of groups of stripes with different periods are required to be projected for realizing unambiguous phase unwrapping. In time-sequential projection schemes, this increases the projection and data acquisition times by a factor, reducing the measurement efficiency. Therefore, a method for fundamentally breaking the phase shift speed limit, improving the light energy utilization rate, enhancing the system stability, and efficiently realizing the multi-periodic structure light projection is needed. Disclosure of Invention In order to solve the problems in the prior art, the method has the core concept that the spatial morphology generation and the time phase modulation of the structural light fringes are decoupled, namely, the static diffraction optical element is utilized to generate high-quality periodic fringes in a spatially fixed mode, and the wave front phase of the incident laser is subjected to rapid and accurate electric control modulation through the high-speed phase modulator, so that the spatial equivalent translation of the fringes is realized, and any spatial pattern is not required to be refreshed. In one aspect, the present invention provides a laser array-based ultra-high speed dynamic light projection method, including: Combining the outgoing laser beams of the multiple coherent light sources to form combined laser beams propagating along the same optical axis along a second direction, wherein the second direction is perpendicular to the first direction; Applying controllable phase modulation to the combined laser by using a phase modulator to generate modulated laser with different phase states; The modulated laser is incident to a diffraction optical element, and the incident modulated laser is diffracted along a second direction to form periodic structure light stripes according to a grating structure of the diffraction optical element with specific phase distribution; The phase modulator is controlled to be switched between different preset phase states, so that the structural light fringes generate equivalent continuous or stepping phase translation in a second direction; And projecting the phase-shifted structured light stripes to the surface of the object to be measured, and synchronously collecting structured light images modulated by the surface of the object in different phase states. The emergent laser of the multipath coherent light source is subjected to step-by-step beam combination treatment through a polarization spectroscope, and the method comprises the following steps: the polarization direction of partial emergent laser light in the laser array is rotationa