A simple technique for wavelength modulation of optical spectra.

A technique for wavelength modulation of optical spectra easily applicable to any type of monochromator is described. The device consists of a blade of transparent material fastened on a piezoelectric transducer; this assembly is mounted behind the entrance slit of the monochromator. Structure in a spectrum is enhanced by the wavelength modulation technique, even if it is superimposed on an intense background. Important features of this device are that it does not alter the adjustment of any element in the monochromator, its effect on the alignment of the monochromator is negligible for most applications, and it can be very easily removed from the monochromator. Examples of its use are given and the electronic equipment is described.