| 摘要 |
An interferometric spectrum analyzer employs a pair of Bragg cells arranged in an optically cascaded configuration such that both the signal beam and the reference beam travel along a common optical path. The beam-modifying properties of the Bragg cells are such that within a prescribed bandwidth of operation, the deflection properties of the respective cells are frequency complementary, namely different frequencies applied to the respective cells deflect the beam passing therethrough along the same optical path, to produce a beat frequency at the Fourier transform plane. In accordance with a first embodiment, complementary deflection action is achieved by using Bragg cells having respectively different acoustic velocites. In a second embodiment, each Bragg cell has the same acoustic velocity. The deflection/frequency complementary effect is obtained by the use of a birefringent material prism interposed between the Bragg cells, which produces angular deviation that depends upon the polarization and the direction of propagation of light passing through the prism.
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