Split unit
A split unit capable of providing a stereoscopic image having less laterality is provided. The split unit includes: a beam splitter which transmits first imaging light as a part of light incident on an incident surface of the beam splitter, and reflects second imaging light as another part of the light incident on the incident surface; and a reflecting member which reflects the second imaging light reflected by the beam splitter. At least one of a reflectance of the reflecting member and a beam splitting characteristic of the beam splitter is set based on the following formulae: T=d /(1+ d ) R =1− T where T (0≦T≦1) is a transmittance of the beam splitter, R (0≦R≦1) is a reflectance of the beam splitter, and d (0≦d≦1) is a reflectance of the reflecting member.
1. A split unit comprising:
a beam splitter which transmits first imaging light as a part of light incident on an incident surface of the beam splitter, and reflects second imaging light as another part of the light incident on the incident surface; and
a reflecting member which reflects the second imaging light reflected by the beam splitter, wherein
at least one of a reflectance of the reflecting member and a beam splitting characteristic of the beam splitter is set based on the following formulae:
T=d /(1+ d )
R= 1− T
where
T (0≦T≦1) is a transmittance of the beam splitter,
R (0≦R≦1) is a reflectance of the beam splitter, and
d (0≦d≦1) is a reflectance of the reflecting member.
2. The split unit according to claim 1 , wherein
a beam splitting ratio of the beam splitter is set such that when light having a predetermined design center wavelength is incident on the beam splitter, the amount of the second imaging light reflected by the reflecting member and the amount of the first imaging light transmitted through the prism are substantially equal to each other, and when light having a wavelength in a visible region other than the design center wavelength is incident on the beam splitter, the beam splitting ratio is within a predetermined allowable range.
3. The split unit according to claim 1 , wherein
at least one of the reflectance of the reflecting member and the beam splitting characteristic of the beam splitter is set such that a difference between brightness of an image formed by the second imaging light reflected by the reflecting member and brightness of an image formed by the first imaging light transmitted through the prism is not smaller than 0% but not larger than 35%.
4. The split unit according to claim 1 , wherein
the beam splitting ratio of the beam splitter is set based on the average of transmittances of P-polarized light and S-polarized light.
5. The split unit according to claim 4 , wherein
the beam splitting ratio of the beam splitter is set based on the average of transmittances of P-polarized light beams having a plurality of incident angles and S-polarized light beams having a plurality of incident angles.