Spectroscopic characteristics acquisition unit, image evaluation unit, and image forming apparatus

摘要

A spectroscopic characteristics acquisition unit includes a light emitting unit to illuminate a measurement target; a lens array including lenses to receive reflected light reflected from the measurement target; a light blocking member having a pinhole array including openings; a focusing unit to focus light coming from the pinhole array; a diffraction unit to diffract the light to different directions depending on wavelength of light received by the focusing unit; and a light receiving unit to receive the reflected light diffracted by the diffraction unit. The light receiving unit includes a spectroscopic sensor array having spectroscopy sensors including pixels. Each of the lenses constituting the lens array corresponds to one of the openings of the pinhole array. The numerical aperture NA of the lens in the arrangement direction in the lens array satisfies the formula NA>sin(thetamax) with respect to the maximum angle of view thetamax of the focusing unit.