The optical system design mainly considers the luminous flux utilization of the light source. Specific performance indicators include light intensity, uniformity, saturation, and spot size. There are two aspects that affect the above indicators: one is the light source, and the other is the optical system structure and material selection. At present, domestic and foreign manufacturers and users basically recommend OSRAM or PHILIPS 1200W short arc double-ended metal gas discharge lamps. Its characteristics are compactness, high brightness, high color temperature, good color rendering and a relatively stable color temperature during lamp dimming. The disadvantage is that the delamination of the filler in the lamp, that is, the presence of the ribbon in the arc imaging or the condensation in the arc tube, forms a shadow effect, which needs to be controlled to a minimum in the optical structure design. In the optical structure, in order to obtain a uniform mixed beam, a parabolic mirror can be used. To collect a divergent or narrow beam, a mirror with a scaled or surface texture should be selected. A reflector system made of a specularly reflective material is better than a refractive system. When it is desired to obtain several beams from a single source, a refractive system combining prisms or lenses can be employed. At present, the optical design of the 1200W moving head computer lamp at home and abroad adopts a lens combination method, and is composed of an aspherical (ie, parabolic) quartz lens.
The most important characteristic of a parabolic lens is to place a point source at the focus, which will result in a parallel beam. In the design of the optical path, it is also necessary to consider the relationship between the light intensity distribution curve, the shape and the size of the light source, the size of the aperture of the reflective lens, and the shape of the light source.