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US 7,023,592 B2Granted
Band-pass filter and image display apparatus
AssigneeMinolta Co., Ltd.
InventorsTetsuya Noda, Yasushi Tanijiri, Takeshi Endo, Hiroaki Ueda
Life of this patent
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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.
Claims10
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 first performed and transmission is subsequently performed at different incident angles at the reflecting optical element,
- wherein a wavelength distribution of an incident light beam is narrowed when the light beam is first reflected by the reflecting optical element, and the wavelength distribution of the incident light beam is cut when the light beam is subsequently transmitted by the reflecting optical element.
A band-pass filter comprising:
- a reflecting optical element for reflecting and transmitting an incident light beam as a function of wavelength and angle of incidence, the band-pass filter being configured such that an optical path of the incident light beam causes the incident light beam to be reflected at least once by the reflecting optical element at a first angle of incidence, and to be transmitted by the reflecting optical element at least once at a second angle of incidence, the second angle of incidence being different from the first angle of incidence,
- wherein a wavelength distribution of the incident light beam is substantially narrowed upon being reflected by the reflecting optical element and the wavelength distribution of the incident light beam is cut upon being transmitted by the reflecting optical element.
A band-pass filter comprising:
- a reflecting optical element for reflecting and transmitting an incident light beam as a function of wavelength and angle of incidence, the band-pass filter being configured such that an optical path of the incident light beam causes the incident light beam to be reflected at least once by the reflecting optical element at a first angle of incidence, and to be transmitted by the reflecting optical element at least once at a second angle of incidence, the second angle of incidence being different from the first angle of incidence,
- wherein a wavelength region on a longer wavelength side of a wavelength distribution of the incident light beam is cut upon one of being reflected and transmitted by the reflecting optical element, and
- wherein a wavelength region on a shorter wavelength side of the wavelength distribution of the incident light beam is cut upon the other one of being reflected and transmitted by the reflecting optical element.
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 transmission is first performed and reflection is subsequently performed at different incident angles at the reflecting optical element,
- wherein a wavelength distribution of an incident light beam is narrowed when the light beam is first transmitted by the reflecting optical element, and the wavelength distribution of the incident light beam is cut when the light beam is subsequently reflected by the reflecting optical element.
Dependencies are inferred from the claim text.