Illumination optical system for endoscope, optical adapter for endoscope, and optical element

An optical adapter configured for use with an endoscope, the optical adapter comprising:

• an optical element comprising:
• an incident surface configured to connect to a distal end portion of an insertion section of the endoscope, light from the distal end of the insertion section being made incident on the incident surface as incident light, and
• an emission surface for emitting the light as illumination light;
• and
• an illumination window for emitting the illumination light emitted from the emission surface of the optical element,
• wherein the emission surface includes a diffusing section that diffuses the emitted light,
• the diffusing section includes a plurality of convex-shaped sections extending in a predetermined direction on the emission surface, and
• each of the convex-shaped sections comprising:
• a total reflection surface having a first angle with respect to the emission surface, the total reflection surface totally reflecting the incident light, and
• a transmission surface having a second angle smaller than the first angle with respect to the emission surface, the transmission surface transmitting and emitting reflected light totally reflected on the total reflection surface and the incident light.

An optical element comprising:

• an incident surface on which light is made incident as incident light;
• and
• an emission surface for emitting the light as emitted light,
• wherein the emission surface includes a diffusing section that diffuses the emitted light,
• the diffusing section includes a plurality of convex-shaped sections extending in a predetermined direction on the emission surface, and
• each of the convex-shaped sections comprising:
• a total reflection surface having a first angle with respect to the emission surface, the total reflection surface totally reflecting the incident light, and
• a transmission surface having a second angle smaller than the first angle with respect to the emission surface, the transmission surface transmitting and emitting reflected light totally reflected on the total reflection surface and the incident light.