Abstract: A high resolution multiple channel imaging spectrometer employing a pair of reflective gratings to create and separate, respectively, a spectrum of discrete spectral channels having high throughput and good channel isolation.

Abstract: Laser beam divergence control is achieved by interposing a pair of optical wedges (41,42) in the beampath of a laser between a pair of lenses (33, 35) of a beam expander (31). The expanded beam has a reduced tendency to jitter during divergence control and the wedges (41, 42) cause a change in divergence by adjusting the optical separation of the lenses (33, 35). By the use of wedges (41, 42) optical length adjustments do not significantly affect directional stability of the beampath.

Abstract: A wavelength monitor (25) uses a diffraction grating (35) and a beam splitter (31). Light from a superluminescent diode (SLD) is supplied to the beam splitter (31) and is projected onto the grating (35).The grating is formed by holographically projecting a diffraction pattern onto a polished surface which is then photoetched, thereby creating a blazed diffraction grating corresponding to the projected pattern. The etched grating is used as a master, wherein the etched grating is coated with reflective material. The reflective material is then transferred to a prepared substrate that has an ultra-low thermal expansion coefficient to form a low cost replica diffraction grating. The grating (35) formed in this manner becomes a very stable and efficient dispersive element that forms a spectrum of the SLD output that is free of ghost images and accurately deproduces the spectral distribution. A pair of optical sensors (41, 42) detect an imbalance in reflected light, providing an indication of wavelength deviation.