Circularl polarization-type polarization diversity element, scanning element using same, and lidar

Abstract

In the prior art, a scanning element used in the autonomous driving car technology of Lidar has inertia due to continuously rotating a mirror or the like by MEMS, and thus is for a raster scan that scans a scene all at once. Such a scanning element was not capable of moving discontinuously from an arbitrary point to another arbitrary point, and performing a high-speed scan that is programmable toan arbitrary frequency and an arbitrary pattern and equivalent to the raster scan. According to the present invention, a Lidar is manufactured comprising a scanning element in which: two polarizationgratings, which have a double refraction director with a thickness corresponding to a half-wavelength plate and rotate with a period ^, are used spaced apart at a desired interval; and a polarizationdiversity method, in which the half-wavelength plate is inserted in the path of one among two light beams, that is, a clockwise-circularly polarized light beam and a counterclockwise-circularly polarized light beam, separately emitted according to the rotation direction of the circularly polarized light, is adopted to achieve a conversion into parallel and proximate circularly polarized light beams having the same rotation direction, wherein the scanning element combines structures in which pairs of a polarization switch and the polarization grating are connected in multiple stages.

Description

Technical field [0001] The invention relates to a circularly polarized light element and a beam digital scanning element, as well as a laser radar and scanning method using the same. Background technique [0002] figure 1 This is an example of polarization diversity as a conventional polarization control technology (Patent Document 1). After being split into two orthogonal linear polarized lights by the polarization beam splitter 102, they are rotated by the polarization rotating element 107 in one optical path, so that the polarization of the light transmitted in the two optical paths is the same (here, the linear vibrating in the vertical direction). Polarized light). However, this polarization diversity method is effective for devices that operate by linear polarization, and devices that operate by circular polarization cannot be used. [0003] on the other hand, figure 2 The configuration of a laser radar using a microelectromechanical mirror 8 as a conventional scanning ele...

AI Technical Summary

Problems solved by technology

However, in the above-mentioned conventional scanning device, the same scanning is performed, and high-speed scanning of any point cannot be programmed with any frequency and any pattern.

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