Band-pass filter and image display apparatus

• US 20030099009A1
• Filed: 11/14/2002
• Published: 05/29/2003
• Est. Priority Date: 11/26/2001
• Status: Active Grant

• Current Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Original Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Inventors: Tanijiri, Yasushi, Noda, Tetsuya, Endo, Takeshi, Ueda, Hiroaki
• Granted Patent: US 7,023,592 B2
• Time in Patent Office: Days
• US Class Current: 359/15
• CPC Class Codes: G02B 5/28 Interference filters
• CPC Class Codes: G02B 5/32 Holograms used as optical elements

Abstract

A band-pass filter has a reflecting optical element having a fixed reflection angle selection region for wavelengths of a given region, and has an optical path such that reflection is performed at least once and transmission is performed at least once at the reflecting optical element.

Claims

1. A band-pass filter comprising

a reflecting optical element having a fixed reflection angle selection region for wavelengths of a given region, and has an optical path such that reflection is performed at least once and transmission is performed at least once at the reflecting optical element.

2. A band-pass filter as claimed in claim 1, wherein a wavelength of a light beam reflected by the reflecting optical element is narrowed by being cut when the light beam is transmitted.

3. A band-pass filter as claimed in claim 1, wherein the reflecting optical element is a volume-phase holographic optical element, a multilayer film or a multilayer filter.

4. A band-pass filter comprising:

at least two reflecting optical elements each having a fixed reflection angle selection region for wavelengths of a given region, and has an optical path such that the optical wave is reflected at least once by at least one of the reflecting optical elements and either reflection or transmission is performed at another of the reflecting optical elements.

5. A band-pass filter as claimed in claim 4, wherein a wavelength of a light beam reflected by the reflecting optical element is narrowed by being cut when the light beam is transmitted.

6. A band-pass filter as claimed in claim 4, wherein a wavelength of a light beam reflected by one of the reflecting optical elements is narrowed by being cut when the light beam is reflected by another of the reflecting optical elements.

7. A band-pass filter as claimed in claim 4, wherein a wavelength of a light beam reflected by one of the reflecting optical elements is narrowed by being cut when the light beam is reflected and transmitted by another of the reflecting optical elements.

8. A band-pass filter as claimed in claim 4, wherein a wavelength of an incident light beam is cut when the light beam is reflected and transmitted by one of the reflecting optical elements, and the wavelength is narrowed by being cut when the light beam is transmitted and reflected by another of the reflecting optical elements.

9. A band-pass filter as claimed in claim 4, wherein the reflecting optical elements are volume-phase holographic optical elements, multilayer films or multilayer filters.

10. A band-pass filter that comprises

at least two reflecting optical elements each having a fixed reflection angle selection region for wavelengths of a given region, and has an optical path such that the optical wave is reflected at least once and transmitted at least once by at least one of the reflecting optical elements and either reflection or transmission is performed by another of the reflecting optical elements.

11. A band-pass filter as claimed in claim 10, wherein a wavelength of a light beam reflected by the reflecting optical element is narrowed by being cut when the light beam is transmitted.

12. A band-pass filter as claimed in claim 10, wherein a wavelength of a light beam reflected by one of the reflecting optical elements is narrowed by being cut when the light beam is reflected by another of the reflecting optical elements.

13. A band-pass filter as claimed in claim 10, wherein a wavelength of a light beam reflected by one of the reflecting optical elements is narrowed by being cut when the light beam is reflected and transmitted by another of the reflecting optical elements.

14. A band-pass filter as claimed in claim 10, wherein a wavelength of an incident light beam is cut when the light beam is reflected and transmitted by one of the reflecting optical elements, and the wavelength is narrowed by being cut when the light beam is reflected and transmitted by another of the reflecting optical elements.

15. A band-pass filter as claimed in claim 10, wherein the reflecting optical elements are volume-phase holographic optical elements, multilayer films or multilayer filters.

16. A band-pass filter that comprises at least two reflecting optical elements each having a fixed reflection angle selection region for wavelengths of a given region, and has an optical path such that reflection is performed once and transmission is performed once by at least two of the reflecting optical elements.

17. A band-pass filter as claimed in claim 16, wherein a wavelength of a light beam reflected by the reflecting optical element is narrowed by being cut when the light beam is transmitted.

18. A band-pass filter as claimed in claim 16, wherein a wavelength of a light beam reflected by one of the reflecting optical elements is narrowed by being cut when the light beam is reflected by another of the reflecting optical elements.

19. A band-pass filter as claimed in claim 16, wherein a wavelength of a light beam reflected by one of the reflecting optical elements is narrowed by being cut when the light beam is reflected and transmitted by another of the reflecting optical elements.

20. A band-pass filter as claimed in claim 16, wherein a wavelength of an incident light beam is cut when the light beam is reflected and transmitted by one of the reflecting optical elements, and the wavelength is narrowed by being cut when the light beam is reflected and transmitted by another of the reflecting optical elements.

21. A band-pass filter as claimed in claim 16, wherein the reflecting optical elements are volume-phase holographic optical elements, multilayer films or multilayer filters.

22. A band-pass filter as claimed in claim 16, wherein a volume-phase holographic optical element has at least two different diffraction center wavelengths, and limits at least two wavelengths.