The invention provides a projector apparatus incorporating a prism optical system of positive refracting power working for size reductions, which apparatus comprises a display device 1, a prism optical system 3 that has positive refracting power and is adapted to enlarge and project an image on the display device, and a stop 4 located on a projection side thereof. Preferred compounds are in the family of diphenylbarbituric acid and analogs. A cap is provided, the contour of which is complementary to that of the aperture, which is mounted articulated on the cover between a service position in which it blocks off the aperture and an open raised position in which the aperture is clear. A database stores a record reflecting the second time for the second incoming telephone call. The method comprises the step of performing electron beam exposure or ion beam exposure for drawing only on a diffraction grating region on which said diffraction grating is provided in correspondence with a pattern of said diffraction grating, and masking the diffraction grating region and exposing a region other than said diffraction grating region with light or X-rays. MSA also can be converted into gasoline, olefins, or other valuable chemicals.