Patent ID: 7274012

Claim:
A light detection device, comprising: a light source to emit light; a wavelength controller to control a wavelength of the light emitted from the light source so as to form the light spot in a desired shape; an optical fiber probe that includes an optical fiber including a core through which the light emitted from the light source travels; and an optical probe configured to emit the light from a projecting end portion of the core; a movement controller to move either one of the optical fiber probe and a sample in a direction toward and away from the other one such that a light spot of propagating light traveling through the core is formed on a surface of the sample to be measured; and a detector to detect light returning from the surface to be measured; wherein an inclination angle of a normal line of a part or all of a surface of the optical probe with respect to an optical axis of the propagating light that travels through the core is smaller than a total reflection angle of the propagation light but greater than zero degrees.