Laser speckle suppression device and method for 3D vision

Abstract

The invention relates to a laser speckle suppression device and method for 3D vision, and the device comprises a laser, a first optical element which is used for collimating a laser line width direction, a second optical element which is used for collimating a laser line length direction, and a movement mechanism. The whole or part of the second optical element is driven to generate relative displacement relative to the first optical element in the line length direction and / or the direction in which the laser is transmitted to the working face, so that the laser generates relative movement on the working face in the line length direction, and the emitting position of the laser on the laser emitting face of the second optical element is changed. The laser generates relative motion on the working surface along the line length direction, the position and shape of the speckle on the working surface are changed, the speckle effect is inhibited, the line width of the laser line is not changed, the beam quality of the laser in the line width direction is not worsened, and the measurement precision is not influenced.

Description

technical field [0001] The invention relates to the technical field of 3D vision, in particular to a laser speckle suppression device and method for 3D vision. Background technique [0002] Lasers are widely used in various fields due to their high coherence, high collimation and high brightness. But not in all applications, these properties of the laser have a positive effect. For example, in the field of 3D measurement using laser triangulation, the high coherence of laser light will lead to a decrease in measurement accuracy. This is because after the laser is irradiated on the rough surface, it will form countless independent scattering surface elements after reflection. Due to the high correlation of the laser, these scattered light will interfere in the process of spatial propagation, forming a granular speckle pattern—— Laser speckle. The principle of laser triangulation is to use the position of the laser on the target surface of the camera to determine the height...

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Problems solved by technology

[0003] There are two existing laser speckle suppression methods: one is the static speckle elimination method, such as splitting the laser beams and then recombining them, which is complicated to operate, large in size, and poor in stability; the other is the dynamic speckle elimination method For example, by changing the temperature of the laser to change the output wavelength of the laser, on the one hand, this method has a small range of changes in the wavelength of many lasers with temperature, and the effect of dispersing spots is not increased; on the other hand, it will increase the wavelength of the light source FHWM, thereby increasing the filter The FHWM is not conducive to the ambient light resistance of the shooting system

There are also some manufacturers who adopt the scheme of rotating or vibrating scatterers (frosted glass), such as the low speckle laser emitter device disclosed in the patent CN211904057 U. The central axis rotates, but when this method suppresses the speckle, it also deteriorates the beam quality in the laser direction, resulting in poor measurement accuracy. Although the patent uses an aperture to reduce the influence of the laser in the line width direction, But also cause loss of laser energy

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