Femtosecond laser system for processing micro-hole array

A femtosecond laser system for processing a micro-hole array, comprising:

• a femtosecond laser, a half-wave plate, a polarizer, a concave lens, a convex lens, a diaphragm, a mechanical shutter, a phase-type spatial light modulator, a first plano-convex lens, a reflecting mirror, a second plano-convex lens, a dichroic mirror, a camera, a processing objective lens, a six-axis translation stage and a transmissive white light source;
• wherein the femtosecond laser, the half-wave plate, the polarizer, the concave lens, the convex lens, the diaphragm and the mechanical shutter are sequentially arranged on a first optical axis;
• wherein the mechanical shutter is configured to control a femtosecond laser beam to be incident on the phase-type spatial light modulator to generate a spatially shaped femtosecond laser pulse;
• wherein the spatially shaped femtosecond laser pulse sequentially passes through the first plano-convex lens, the reflecting mirror, the second plano-convex lens and the dichroic mirror to reach the processing objective lens, and is focused by the processing objective lens to be irradiated on a sample to be processed on the six-axis translation stage to form the micro-hole array for the sample;
• wherein the half-wave plate and the polarizer together constitute an energy adjustment system for adjusting energy of the femtosecond laser and making a polarization direction of the emitted femtosecond laser beam horizontal;
• wherein the phase-type spatial light modulator is configured to perform phase modulation to the femtosecond laser beam according to a phase diagram of the micro-hole array of the sample;
• wherein the concave lens, the convex lens and the diaphragm together constitute a beam expansion system for adjusting a beam waist diameter of the femtosecond laser beam, wherein a front focus of the concave lens and a front focus of the convex lens coincide with each other;
• wherein the dichroic mirror, the camera located at one side of the dichroic mirror, and the transmissive white light source constitute a front imaging unit for acquiring an image of the micro-hole array processed by the femtosecond laser;
• and
• wherein the phase-type spatial light modulator, the first plano-convex lens, the second plano-convex lens, and the processing objective lens together constitute a 4F system, and the 4F system is configured to prevent diffraction effect from happening in a light field modulated by the phase-type spatial light modulator before reaching the processing objective lens, wherein a focal length of the first plano-convex lens is same as that of the second plano-convex lens, a distance between the first plano-convex lens and the second plano-convex lens is twice as long as the focal length, a distance between the first plano-convex lens and a liquid crystal screen of the phase-type spatial light modulator is equal to the focal length, and a distance between the second plano-convex lens and the processing objective lens is equal to the focal length.