Device and method for preparing optical gratings by ultrafast laser direct writing

Abstract

The invention discloses a device and a method for preparing optical gratings by ultrafast laser direct writing, and relates to the field of laser processing optical gratings. A laser beam emitted by alaser is expanded by a beam expanding system, is focused by a focusing system and is irradiated on a workpiece; the laser beam is diverged by a concave lens at first, and then the beam is converted into parallel beams by a convex lens; and the focusing lens comprises a plurality of focusing lenses. The method comprises the steps of: the laser beam is expanded by using a flat concave lens and a flat convex lens, when the expanded parallel laser passes through the focusing system, the focusing system comprises a plurality of focusing lenses, the laser is focused separately to form a plurality of focal points; and according to the same and different focal lengths of the plurality of focusing lenses, the optical gratings are divided into two types. One type is simple periodic gratings capableof being directly written, in which the focal lengths are the same and the focal points are located on the same horizontal line; and the other type is complex periodic gratings capable of being directly written, in which the focal lengths are different and the focal points not located on the same horizontal line. The device provided by the invention overcome the problems that micron optical gratings cannot be easily prepared due to the interference of multiple beams of laser, and that the direct writing efficiency of a single beam are overcome.

Description

technical field [0001] The invention relates to the field of laser processing gratings, in particular to a device for preparing gratings by ultrafast laser direct writing. Background technique [0002] As an important diffractive optical element, gratings are widely used in many fields such as geophysical surveying, seismic observation, ocean research, spacecraft temperature measurement, 3D photography technology, photoacoustic imaging, and solar cells. At present, common grating preparation methods include mechanical scribing, electron beam exposure, focused ion beam etching, optical etching, and laser direct writing. [0003] The mechanical scribing method is a method of directional processing on the surface of a material with a knife. When this method is used to process gratings, the requirements for the knife are very high. It needs a sharp blade, high hardness, wear resistance, high temperature resistance, and Corrosion, etc., generally use diamond tools. The mechanic...

AI Technical Summary

Problems solved by technology

However, single-beam direct writing has low efficiency and low processing precision. It is necessary to develop a direct writing method with high writing efficiency and suitable for micron-scale gratings.

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