Optical reflecting unit

An optical reflecting unit comprising:

• a prism having a slanting surface, said slanting surface having a longitudinal direction;
• a half mirror for folding the optical path of light which is incident upon said half mirror in the form of a scan line, and for transmitting a portion of said incident light as a transmitted light, said half mirror arranged relative to the slanting surface along the longitudinal direction;
• an extracted bore in said prism for receiving said transmitted light, said extracted bore having a surface condition wherein said transmitted light is irregularly reflected by a bottom and a peripheral wall of said extracted bore;
• and
• an irregular element, provided on the bottom and the peripheral wall of said extracted bore, for irregularly reflecting the transmitted light transmitted through said half mirror and for attenuating said transmitted light.

An optical reflecting unit comprising:

• a prism having a slanting surface, said slanting surface having a longitudinal direction;
• a half mirror for folding the optical path of light which is incident upon said half mirror in the form of a scan line, and for transmitting a portion of said incident light as a transmitted light, said half mirror arranged relative to the slanting surface along the longitudinal direction;
• and
• a through bore in said prism for receiving said transmitted light and for passing said received transmitted light outside of said prism.

An optical reflecting unit comprising:

• a prism having a slanting surface, said slanting surface having a longitudinal direction;
• a half mirror for folding the optical path of light which is incident upon said half mirror in the form of a scan line, and for transmitting a portion of said incident light as a transmitted light, said half mirror arranged relative to the slanting surface along the longitudinal direction;
• an extracted bore in said prism for receiving said transmitted light;
• a mirror within the extracted bore for reflecting said transmitted light;
• and
• a through bore for conveying said transmitted light reflected by said mirror within the extracted bore outside of said prism.

An optical reflecting unit comprising:

• a prism having a slanting surface, said slanting surface having a longitudinal direction;
• a half mirror for folding the optical path of light which is incident upon said half mirror in the form of a scan line, and for transmitting a portion of said incident light as a transmitted light, and for reflecting a portion of said incident light to a light receiving means, said mirror arranged relative to the slanting surface along the longitudinal direction;
• and
• an extracted bore in said prism for receiving light transmitted through said half mirror and having a shape which substantially prevents reflection of said transmitted light to said light receiving means.