
A wavelength monitoring device for monitoring a beam of light is disclosed having a beam splitter, with opposing first and second spaced apart faces, for receiving optical radiation from the beam of light to be monitored. In operation the first face reflects a first portion of the optical radiation to a first photodiode. The second face includes a grating for reflecting a second portion of the optical radiation to the first photodiode. The grating also reflects a third portion of optical radiati...











