## Iqf1

Fig. 4.31. "Lensm" design of Su [4.64] for an ADC integrated into a doublet corrector for a 5 m, f/2 to f/4.5 strict RC (Cassegrain) focus. The glasses are from the Chinese glass catalogue

BaK4l paper. Su gives spot-diagrams for two dispersion rotations. The individual spot-diagrams are within 0.5 arcsec for a field diameter of 45 arcmin, most of them being much smaller. The largest total dispersion from 350 to 1014 nm is 7.6 arcsec, sufficient for Z ~ 70°. Su also gives a diagram of secondary spectrum errors compared with the atmospheric dispersion function.

In 1990 this work was followed up by a detailed analysis by Wang and Su [4.65] of similar fully integrated ADC in PF correctors. All cases concerned correctors for a 7.5m, f/2 'paraboloid. Three types of lensm corrector were used, two of which are shown in Fig. 4.32. These are based on standard types of corrector of the sort proposed by Faulde and Wilson [4.30] and Wynne [4.28] respectively.

Figure 4.33 shows the field points for the calculation of spot-diagrams. Spot-diagrams are reproduced for lensm corrector type I in Fig. 4.34 for a field diameter of 45 arcmin and zero dispersion. The significance of the vertical scale of 6 arcsec is that this represents the maximum dispersion of the lensm corrector for the wavelength range 350 to 1014 nm. The mean diameters of the spot diagrams for 434 nm, 350 nm and 1014 nm respectively are 0.29,

Type I Type n

Fig. 4.32. Two types of lensm corrector designed by Wang and Su [4.65] for the PF of a 7.5 m, f/2 paraboloid

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