Patent ID: 6930776
Filing Date: 2005-08-16
Classification: G01J

Abstract:
1. A dual-channel, double-filtering, multi-pass optical spectrum analyzer comprising: (i) a diffraction grating (DG); (ii) first and second input ports (P (iii) polarization-decomposing means (PDM) for decomposing a single light beam into first and second components having mutually-orthogonal linear states of polarization and supplying said first and second components to said first and second input ports as said first and second input light beams (LR, LT), respectively, (iv) a retroreflector means (RAM (v) first and second intermediate output ports (P (vi) first and second secondary input ports (P (vii) first and second output ports (P (viii) means (TT) for rotating at least one of the first retroreflector and the grating to effect wavelength scanning; (ix) first and second detectors (D′, D″) for receiving the first and second light beams from the first and second output ports (P (x) microprocessor means (MP) coupled to said rotating means (TT) and to the detectors (D′, D″) for controlling rotation of the first retroreflector (RAM the arrangement being such that, each time the first and second light beams are incident upon the diffraction grating, their linear states of polarization are substantially parallel to each other and the dispersion planes for all wavelengths within an operating band of the optical spectrum analyzer.