3. Flat-grating optical assembly

3.1 Conventional plan network

Conventional flat gratings are only used for monochromators. Concave mirrors are then required for input and output collimation to obtain parallel beams. When a single concave mirror is used (on two different parts), we obtain the Ebert set-up. When two concave mirrors are used, we obtain the Czerny-Turner set-up (figure 5 ). The focal length f of the mirrors defines the focal length of the dispersive system, and the inverse 1/f defines the aperture of the system. Line selection is obtained by rotating the grating on its axis. In this case, the grating equation is used to calculate the diffraction angles, with α – β = 2i = Cte (see §...