Acousto Optical Spectrometer

The principle of an AOS is based on the diffraction of light at ultrasonic waves. A piecoelectric transducer, driven by the RF-signal (from the receiver), generates an acoustic wave in a crystal (the so called Bragg-cell). This acoustic wave modulates the refractive index and induces a phase grating. The Bragg-cell is illuminated by a collimated laser beam. The angular dispersion of the diffracted light represents a true image of the IF-spectrum according to the amplitude and wavelengths of the acoustic waves in the crystal. The spectrum is detected by using a single linear diode array (CCD), which is placed in the focal plane of an imaging optics.

Additional recommended knowledge

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Weighing the right way

Depending on the crystal and the focal length of the imaging optics, the resolution of this type of spectrometer can be varied.