Illumination optical system for endoscopes

An illumination optical system for an endoscope comprising:

• a light emitting means and an illumination lens system that comprises a positive lens component for directing rays emitted from said light emitting means to an object to be observed;
• wherein said positive lens component comprises an aspherical surface having such a shape as to have curvature which becomes lower than that on a reference sphere thereof as portions of said aspherical surface are farther from an optical axis,
• wherein said light emitting means has a light emitting surface extending in a direction perpendicular to the optical axis of said illumination lens system,
• wherein said illumination lens system satisfies the following condition:
• h=f.cndot..theta.
• wherein the reference symbol h represents a height of incidence, on said illumination lens system, of a ray which is emitted from said light emitting means in parallel with the optical axis of said illumination lens system, the reference symbol .theta. designates an angle of emergence, from said illumination lens system, of the ray having the height of incidence h and the reference symbol f denotes a focal length of said positive lens component, and
• wherein said illumination lens system further satisfies the following conditions:
• ##EQU16## wherein the reference symbol F(h) represents a function for expressing a shape of said aspherical surface, the reference symbol D designates a maximum value of said height of incidence ray, the reference symbol f.sub.1 denotes a focal length of a lens component having the aspherical surface when the aspherical surface is replaced with the reference sphere thereof, and the reference symbol n represents the refractive index of the lens component having the aspherical surface.

An illumination optical system for endoscopes comprising:

• a light emitting means and an illumination lens system comprising a positive lens component for directing rays emitted from said light emitting means to an object to be observed;
• wherein said illumination lens system comprises an aspherical surface having such a shape as to have curvature which becomes lower than that on a reference sphere thereof as portions of said aspherical surface are farther from an optical axis,
• wherein said illumination optical system satisfies the following conditions:
• ##EQU17## wherein the reference symbol h represents a height of incidence, on said illumination lens system, of a ray which is emitted from said light emitting means in parallel with the optical axis of said illumination lens system, the reference symbol .theta. designates an angle of emergence, from said illumination lens system, of the ray having the height of incidence h and the reference symbol f denotes a focal length of said positive lens component, the reference symbol F(h) represents a function for expressing said aspherical surface, the reference symbol D designates a maximum value of said height of an incidence ray, the reference symbol f.sub.1 designates a focal length of a lens component having the aspherical surface when said aspherical surface is replaced with, a reference sphere thereof and the reference symbol n represents the refractive index of the lens component having said aspherical surface.

An illumination optical system for endoscopes comprising:

• a light emitting means and an illumination lens system including a positive lens component for directing rays emitted from said light emitting means to an object to be observed;
• wherein said illumination lens system comprises an aspherical surface having such a shape as to have a curvature which becomes lower than that of a reference sphere thereof as portions of said aspherical surface are farther from the optical axis, and
• wherein said positive lens component further satisfies the following conditions:
• ##EQU18## wherein the reference symbol F(h) represents a function for expressing a shape of said aspherical surface, the reference symbol D designates a maximum value of the height of incidence h, the reference symbol f represents the focal length of a lens component having said aspherical surface when said aspherical surface is replaced with a reference sphere thereof and the reference symbol n represents a refractive index of a lens component having said aspherical surface.

An illumination optical system for endoscopes comprising:

• a light emitting means and an illumination lens system which comprises a positive lens component and serves for directing rays emitted from said light emitting means to an object to be observed;
• wherein said illumination lens system comprises an aspherical surface having such a shape as to have a curvature which becomes lower than that of a reference sphere thereof as portions of said aspherical surface are farther from an optical axis,
• wherein a positive lens component is disposed between said lens component having the aspherical surface and said light emitting means, and
• wherein said illumination optical system satisfies the following condition:
• .phi..sub.3 <.phi..sub.2
• wherein the reference symbol .phi..sub.2 represents a refractive power of a reference sphere of a surface, disposed on the side of said light emitting means, of the lens component having said aspherical surface and the reference symbol .phi..sub.3 designates a refractive power of a reference sphere of an object side surface of said positive lens component disposed between said lens component having the aspherical surface and said light-emitting means.