Abstract: The invention is directed to an acousto-optic dispersive light analyzer (AODLF) which is an electronically adjustable spectroscopic device capable of instantaneously monitoring many wavelengths with a fixed drive frequency. The AODLF has about a one octave range, whose center is selected by changing the RF. The resolution of the AODLF in the infrared is several thousand, and it is electronically adjustable. The acousto-optic device according to this invention is particularly useful for the detection and analysis of short light pulses. An additional capability of the AODLF is its operation in a derivative mode for enhanced SNR of coherence detection in the presence of a high incoherent background by imposing a very small frequency modulation on the RF applied to the AODLF. Then by phase locking each of the detector element signals at first the fundamental and then the first harmonic of the FM, the first and second spectrum derivatives of each resolution element can be observed.