Polarization converting apparatus and optical instrument having the same

• US 5,461,500 A
• Filed: 08/22/1994
• Issued: 10/24/1995
• Est. Priority Date: 05/08/1990
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Suzuki, Hidetoshi, Kimura, Kazumi, Mitsutake, Hideaki, Kawasaki, Shigeru, Mochizuki, Noritaka, Kurematsu, Katsumi, Tsuji, Sadahiko, Shingaki, Junko, Minoura, Nobuo
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US08/293,738
• Time in Patent Office: 428 Days
• Field of Search: 359/70, 359/487, 359/500, 359/858, 359/859, 359/48, 359/49, 359/50, 359/495, 359/499, 313/112, 313/114
• US Class Current: 349/9
• CPC Class Codes: G02B 27/283 used for beam splitting or combining

Abstract

This specification discloses a polarization converting apparatus having means emitting non-polarized light, and polarizing means having a light incidence surface and a light emergence surface, the polarizing means receiving the non-polarized light by the light incidence surface and causing polarized light to emerge from the light emergence surface, the size and shape of the light incidence surface being similar to the size and cross-sectional shape of the non-polarized light. The specification also discloses an optical instrument having such apparatus.

Claims

1. An illumination apparatus comprising:

an optical system having a rectangular incident surface for converting non-polarized light to polarized light;

a mirror having a substantially rotation-symmetrical reflection surface for reflecting light from a light source toward said rectangular incident surface of said optical system, said mirror including a rectangular opening facing said optical system for making the light from said light source pass therethrough as light beam which cross-sectional portion is substantially rectangularly shaped;

wherein said optical system comprises a polarization light beam splitter for splitting said non-polarized light into a first polarized light and a second polarized light which polarization directions are mutually intersected and

means for changing a polarization state of said first polarized light so that an illumination-objected surface is illuminated by said first second polarized lights in which the polarization directions thereof are mutually consistent.

2. An illumination apparatus comprising a rectangular image generating means for generating an image by modulating said first and second polarized light from the illumination apparatus according to claim 1.

3. An illumination apparatus according to claim 1,

wherein said polarization beam splitter splits said first and second polarized light as a reflected light and a transmitted light thereby to be directed toward mutually intersected directions and

said optical system includes a folding mirror in order that said second polarized light transmitted through said polarization beam splitter is reflected such that an optical path of said second polarized light is folded by 90°

whereby the folded optical path is made to be parallel to the optical path of said first polarized light reflected by said polarization light beam splitter.

4. An illumination apparatus according to claim 3

wherein said folding mirror includes a first reflection surface for reflecting light from said light source toward said opening and a second reflection surface for reflecting the light emitted from said light source toward outside of said opening so as to be directed to said light source.

5. An illumination apparatus comprising a rectangular image generating means for generating an image by modulating said first and second polarized light from the illumination apparatus according to claims 3 or 4.

6. An illumination apparatus according to claim 1,

wherein said polarization light beam splitter system splits said first and said second polarized light as a reflected light and a transmitted light to be directed toward mutually intersected directions, and

said optical system includes a second polarization beam splitter having construction in which the end portion of said second polarization beam splitter and that of said polarization light beam splitter are disposed so as to be mutually abutted whereby a roof-shaped portion is formed thereby

wherein said second polarization light beam splitter first transmits said second polarized light through said polarization light beam splitter after the polarization plane is rotated by said means for changing a polarization state of said first polarized light toward a direction parallel to an optical path of said first polarized light.

7. An illumination apparatus according to claim 6,

wherein said mirror includes a first reflection surface for reflecting light from said light source toward said opening and a second reflection surface for reflecting the light emitted from said light source toward outside of said opening so as to be directed to said light source.

8. An illumination apparatus comprising a rectangular image generating means for generating an image generated by modulating said first and second polarized light from the illumination apparatus according to claims 6 or 7.