One-meter double-pass monochromator

Summary form only given. The registration of optical spectra of atoms and molecules with high resolution combined with low stray light and flexibility of the apparatus in a wide wavelength region is usually satisfied by double monochromators. These instruments, however, are larger, more complex and more expensive than the single-pass apparatus These shortcomings could be avoided by repeating using of only one dispersion element. There are several types devices to realise this idea. Among them, the Walsh (1952) system of mirrors, placed near to the focal plane of single-pass monochromator is most promising. Thus, by turning back the optical beam, the dispersion is doubled. A substantial reduction of stray light can be achieved by mounting an intermediate slit between two Walsh mirrors. We report the design and construction of a one-meter double-pass monochromator in order to study the instrument from the point of view of the compromise of the spectral resolution and luminosity. We use the Czerny-Turner system, since it has low inherent aberrations and it was optimised by a modified version of the ray tracing program. According to theoretical optimisation a double-pass spectrometer was constructed. A 1200 gr/mm diffraction grating with 100×100 mm area is used. A computer controlled sine drive set up and photocounting registration was used. Using the Ne spectrum (5872.8 Å and 5872.1 Å spectral lines) from a hollow cathode lamp the spectrometer resolution was estimated to be about 0.13 Å