Device and method for simultaneously inspecting defects of surface and subsurface of optical element

A device for simultaneously inspecting defects of a surface and a subsurface of an optical element, comprising a laser excitation device, a laser interference inspection device, a laser scattering inspection device, a motion platform and a sample table, wherein:

• the laser excitation device and the laser interference inspection device adopt lasers of different wavelengths;
• the laser interference inspection device and the laser scattering inspection device adopt lasers of same wavelength;
• the sample table is connected with the motion platform;
• and a sample to be tested is placed on the sample table;
• the motion platform drives the sample to be tested to move in a three-dimensional space of X, Y and Z, so that a surface and a subsurface of the sample to be tested are scanned and inspected;
• the laser excitation device comprises an exciting laser device, a scanning galvanometer, and a micro-objective, wherein:
• the exciting laser device generates a pulsed exciting laser;
• the scanning galvanometer deflects the exciting laser by a certain angle in a scanning plane, and the exciting laser is incident on the micro-objective in different angles;
• the laser interference inspection device comprises an inspection laser device, a Fabry-Perot resonant cavity, a dichroic mirror, an interference photoelectric detector, and an interference signal sampler, wherein:
• the inspection laser device generates continuous inspection lasers;
• the Fabry-Perot resonant cavity comprises a collimating lens, a beam splitting prism, an interference prism, and a piezoelectric ceramic phase shifter;
• the interference photoelectric detector is arranged on a wall of the Fabry-Perot resonant cavity;
• a detecting surface of the interference photoelectric detector is parallel with a surface of a mirror of the piezoelectric ceramic phase shifter, and the two surfaces are distributed at two sides of the interference prism;
• and
• the inspection laser after being emitted by the inspection laser device enters the Fabry-Perot resonant cavity;
• the beam splitting prism splits the inspection laser into two beams, wherein one beam is an interfering inspection laser, and the other beam is a scattering inspection laser;
• the interfering inspection laser is further split into two beams after passing through the interference prism, wherein one beam is a phase shifting laser, and the other beam is a detecting laser;
• the phase shifting laser is vertically incident on the piezoelectric ceramic phase shifter and then returns;
• the detecting laser is emergent through the Fabry-Perot resonant cavity, and then is reflected onto the surface of the sample to be tested by the dichroic mirror;
• the detecting laser, after being reflected by the surface of the sample to be tested, is reflected back to the interference prism by the dichroic mirror, and produces an interference with the phase shifting laser.