Light modulating device and laser processing device

A light modulating device comprising:

• a light source unit for emitting a laser beam and illumination light having respective wavelengths different from each other onto the same optical path;
• a first dielectric multilayer film mirror, formed on a first light transmitting member transparent to the illumination light, for receiving the laser beam and illumination light emitted onto the same optical path from the light source unit, reflecting the laser beam, and transmitting therethrough the illumination light;
• a reflective spatial light modulator for receiving obliquely in front thereof the laser beam from the first dielectric multilayer film mirror, and modulating the laser beam for each of a plurality of two-dimensionally arranged pixels while reflecting the laser beam;
• a second dielectric multilayer film mirror, formed on the first light transmitting member or a second light transmitting member transparent to the illumination light, provided separately from the first light transmitting member, for reflecting the laser beam received from the spatial light modulator and transmitting therethrough the illumination light transmitted through the first dielectric multilayer film mirror, and transmitted through at least the first light transmitting member, onto the same optical path as with the reflected laser beam;
• and
• a light collecting lens for receiving the illumination light and laser beam emitted onto the same optical path from the second dielectric multilayer film mirror and converging the illumination light and laser beam,
• wherein the first light transmitting member is constituted by a prism,
• the first dielectric multilayer film mirror is formed on a first surface of the prism,
• the second dielectric multilayer film mirror is formed on a second surface of the prism and
• the illumination light is entered from the first surface and totally reflected at a third surface of the prism, and the illumination light that is totally reflected propagates to the second surface through the prism.