Light source devices for endoscopes

A light source device for endoscopes comprising:

• a light source and a collector optical system of said light source device for collecting rays emitted from said light source onto an end surface of incidence of a light guide fiber bundle:
• wherein said collector optical system satisfies the following condition (1) and comprises lens components which have aspherical surfaces at least on the side of said light source, and an aspherical lens component disposed on the closest to said light source satisfies the following condition (3):
• sin.theta..ltoreq.G(.theta.)<tan.theta. (1)
• 0.6<(n-1)f/r.sub.1 '<15 (3)
• wherein the reference symbol n represents a refractive index of said aspherical lens components, the reference symbol r.sub.1 ' denotes a radius of curvature on a reference sphere of said aspherical surface, the reference symbol f designates a focal length of said collector optical system as a hole, the reference symbol h represents a height of incidence of a ray which is emitted from said light source in parallel with an optical axis and made incident on said collector lens system, the reference symbols .theta. denotes an angle of emergence, from said collector optical system, of said ray which has the height of incidence h, the reference symbol G(.theta.) represents a quotient of h/f, and wherein said aspherical surface has a shape which is expressed by the formula shown below:
• X=CY.sup.2 /(1+(1-PC.sup.2 Y.sup.2).sup.1/2)+BY.sup.2 +EY.sup.4 +FY.sup.6 +GY.sup.8 +HY.sup.10 +IY.sup.12
• wherein the X axis is taken as the optical axis, the Y axis is taken on a plane parpendicular to the optical axis, the origin is taken as an intersection between the optical axis and the aspherical surface, the reference symbol C represents a curvature of a reference sphere of said aspherical surface, and the reference symbols P, B, E, F, G and H designate coefficients for expressing said aspherical surface, whereas r.sub.1 ' is expressed as 1/2B when both C and P are zero.