Patent ID: 11872655
Assignee: HAMAMATSU PHOTONICS K.K.
Field: Machine tools (Mechanical engineering)
Classification: CPC B  C | IPC B

Claim 1:
2. A laser processing device for performing laser processing on an object to be processed by applying laser light of a first wavelength from a first surface side of the object to be processed to the object to be processed, the laser processing device comprising:
a laser light source configured to output the laser light;
a converging unit configured to converge the laser light toward the first surface to form a converging point;
a camera configured to image reflected light of the laser light from the first surface;
a spatial light modulator configured to modulate the laser light according to a modulation pattern; and
a controller configured to execute acquisition processing of applying the laser light to the first surface by controlling the laser light source and imaging the reflected light by controlling the camera to acquire a reflectance of the first surface with respect to the first wavelength,
wherein before executing the acquisition processing, the controller executes modulation processing of causing the spatial light modulator to present the modulation pattern for lowering a power density of the laser light on the first surface,
wherein as the modulation processing, the controller causes the spatial light modulator to present a spot deformation pattern as the modulation pattern for changing a spot shape of the laser light on the first surface,
wherein the power density is lowered as the spot size of the laser light is expanded based on the spot deformation pattern,
wherein as the acquisition processing, the controller executes
first processing of imaging the reflected light from the first surface by controlling the camera to acquire a first light amount as an amount of the reflected light from the first surface,
second processing of applying the laser light from a side of a reference surface, of which reflectance for the first wavelength is known, to a reference object having the reference surface by controlling the laser light source and imaging reflected light from the reference surface by controlling the camera to acquire a reference light amount as an amount of the reflected light from the reference surface, and
third processing of calculating a reflectance of the first surface for the first wavelength based on the reflectance of the reference surface for the first wavelength, the first light amount, and the reference light amount,

as the modulation processing, the controller causes the spatial light modulator to present the modulation pattern so that a spot shape of the laser light on the first surface in the first processing is different from a spot shape of the laser light on the reference surface in the second processing, and
wherein the power density is lowered as the spot size of the laser light is expanded based on the modulation pattern.