A system with grazing incidence on a grating was developed for precisi
on scanning of the emission Frequency of a dye laser. A glass wedge wi
th a specially selected angle and thickness was located between the gr
ating and an non-transmitting mirror. Rotation of the wedge made it po
ssible to vary the laser frequency so that there was no hopping of the
longitudinal resonator cavity modes, This tuning mechanism made it po
ssible to relax significantly the requirements that the frequency vari
ation system had to satisfy.