Diffraction characteristics of holographic gratings at grazing incidence

Holographic gratings with line frequencies 2100 and 2500 mm^–1 were optimized in respect of the relative diffraction efficiency at grazing incidence for their use in dye lasers. A suitable selection of the exposure and development conditions made it possible to reach an absolute efficiency of 0.2 for an angle of incidence 89°, which was close to the theoretical value. The diffraction characteristic of the gratings with the line frequency 2100 mm^–1 exhibited an anomaly at the wavelength of 488 nm. The gratings with the line frequency 2500 mm^–1 were preferable in the tuning range because of the more uniform wavelength dependence of the efficiency.