Patent ID: 8804118

Claim:
A spectral module comprising: a substrate, having first and second surfaces, for transmitting light and for receiving light incident on the first surface; a light transmitting unit having a third surface and a fourth surface, wherein the third surface receives light from the second surface of the substrate; a spectroscopic unit, formed on the fourth surface of the light transmitting unit, for internally reflecting and spectrally resolving light incident from the second surface of the substrate, wherein the transmitting unit receives the spectrally resolved light internally reflected from the spectroscopic unit and transmits it back to the second surface of the substrate; and a photodetector, disposed on the first surface of the substrate, for detecting the light spectrally resolved by the spectroscopic unit that is received from the light transmitting unit and transmitted through the substrate from the second to the first surface; wherein the second surface is provided with a recess, adapted to mate with the light transmitting unit through an optical resin agent, having a predetermined positional relationship with a reference unit for positioning the photodetector with respect to the substrate; wherein the recess is provided with a first mating section adapted to mate with the light transmitting unit in an extending direction of a grating groove of the spectroscopic unit and a second mating section adapted to mate with the light transmitting unit in a direction substantially orthogonal to the extending direction of the grating groove; and wherein the second mating section and the light transmitting unit have a gap therebetween smaller than that between the first mating section and the light transmitting unit, and wherein the components of the spectral module are configured and arranged so that light propagates through the system in the following way: light incident on the first surface of the substrate is transmitted through the substrate to the second surface of the substrate; light transmits from the second surface of the substrate into the light transmitting unit through the third surface of the light transmitting unit; light transmits through the light transmitting unit and encounters the spectroscopic unit that is disposed on the fourth surface of the light transmitting unit, is internally reflected therefrom and thereby becomes spectrally resolved; the spectrally resolved light propagates back through the light transmitting unit and enters the substrate through the second surface of the substrate; and the spectrally resolved light propagates through the substrate from the second to the first surface and is detected by the photo detector on the first side of the substrate.