1Defined as a ratio of photons gathered inside the FWHM with and without optics. 2Defined as a ratio of photons gathered inside the FWHM with and without optics. deg FOV, cm, both approaches scaled to fit these criteria. deg FOV, cm, both approaches scaled to fit these criteria. Au coated, microroughness Å. The rating of this property is disputatious: larger FOV results in smaller number of modules to build and test, on the other hand, if anything goes wrong, larger part of the sky will be uncovered and higher costs for insitu repair is demanded. Depends on the PSF blurring by distortions, backgroung estimates….