| 摘要 |
PROBLEM TO BE SOLVED: To decrease a void state in the distributed light which enters a light guide by controlling a condenser lens group to satisfy specified conditions. SOLUTION: The illumination device consists of a lamp having a discharge type light source and a paraboloidal reflection mirror disposed in the rear of the light source, and a condenser lens group 3 composed of at least one lens to condense the light emitting from the lamp to a light guide. The device satisfies condition I: 0.5<=4fP/(ϕa×ϕn)1/2<=1.5 and condition II: 0.8<=sin tan-1(D/ fS×0.5)}/NA<=1.2, wherein fP is the focal length of the paraboloida reflection mirror, ϕa is the diameter of the aperture of the paraboloid where the light exits, ϕδn&KHgr;is the diameter of the aperture where electrodes are inserted, fS is the focal length of the final lens in the condense lens group 3. D is the diameter of the beam on the axis of the final lens, and NA is the numerical aperture of the light guide. When the condenser lens group consists of one lens, the lens is regarded as the final lens. Thus, a void state in the distributed light which enters the light guide can be decreased. |
