An optical superheterodyne analyzer, which is destined for high resolution spectral analysis in the optical domain, is described. The optical local oscillator of continuously variable frequency, the core of this analyzer, is obtained by means of an acousto‐optic effect. By changing the acoustic frequency linearly, and by appropriately choosing the order of diffraction, one can scan the frequency of the local oscillator beam over a range of 2.4 GHz. This optical superheterodyne system is analogous to the one used in rf receivers. By this proposed method of optical spectral analysis, we have overcome three drawbacks existing in the classical heterodyne detection. Firstly, the analyzable domain extends to 2.4 GHz instead of 400 MHz for heterodyne detection; secondly, we use a fixed frequency tuned amplifier instead of an expensive rf spectrum analyzer. Finally, there exist no