IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0455969
(1989-12-21)
|
우선권정보 |
JP-0325426 (1988-12-23) |
발명자
/ 주소 |
|
출원인 / 주소 |
- Minolta Camera Kabushiki Kaisha
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
17 인용 특허 :
7 |
초록
▼
An interference filter for use in a copying machine comprises a glass substrate and a plurality of high-refractive index and low-refractive index layers alternately superposed on the substrate for reducing ripples at opposite sides of the reflective range. The first and second layers counted from th
An interference filter for use in a copying machine comprises a glass substrate and a plurality of high-refractive index and low-refractive index layers alternately superposed on the substrate for reducing ripples at opposite sides of the reflective range. The first and second layers counted from the substrate have a greater optical layer thickness than λo/2. The third and fourth layers have a greater optical layer thickness than λo/4. The second top layer has a greater optical layer thickness than λo/2. The top layer has a smaller optical layer thickness than λo/4. The remaining layers have an optical layer thickness equal to λo/4.
대표청구항
▼
1. An interference filter for use in a copying machine to be positioned in an optical path of light passing through an image-forming lens for preventing transmission of light having a predetermined wavelength range about a wavelength, λo, said interference filter comprising: a substrate for carry
1. An interference filter for use in a copying machine to be positioned in an optical path of light passing through an image-forming lens for preventing transmission of light having a predetermined wavelength range about a wavelength, λo, said interference filter comprising: a substrate for carrying a plurality, N, of layers superimposed thereon; said layers including layers of a high-refractive index element arranged at odd-numbered places in order as counted from said substrate, layers of a low-refractive index element arranged at even-numbered places in order as counted from said substrate, and the Nth layer as counted from said substrate being of a low-refractive index element; wherein: the first layer as counted from said substrate has an optical layer thickness greater than λo/2, the second layer as counted from said substrate has an optical layer thickness greater than λo/2, the third layer as counted from said substrate has an optical layer thickness greater than λo/4, the fourth layer as counted from said substrate has an optical layer thickness greater than λo/4, the N-1 layer as counted from said substrate has an optical layer thickness greater than λo/2, and the Nth layer as counted from said substrate has an optical layer thickness smaller than λo/4. 2. An interference filter as claimed in claim 1, wherein the fifth to N-2 layers counted from said substrate have an optical layer thickness equal to λo/4. 3. An interference filter as claimed in claim 1, wherein the first layer has a greater optical layer thickness than the N-1 layer. 4. An interference filter comprising: a substrate for carrying a plurality, N, of layers superimposed thereon; said layers including layers of a high-refractive index element arranged at odd-numbered places in order as counted from said substrate, layers of a low-refractive index element arranged at even-numbered places in order as counted from said substrate, and the Nth layer as counted from said substrate being of a low-refractive index element; wherein: the first layer and a second layer as counted from said substrate have substantially the same optical layer thickness, the third layer and a fourth layer as counted from said substrate have substantially the same optical layer thickness, the N-1 layer as counted from said substrate has an optical layer thickness smaller than said first layer, the Nth layer as counted from said substrate has an optical layer thickness smaller than said fourth layer, and the remaining layers have substantially the same optical layer thickness which is between the optical layer thicknesses of said fourth layer and said Nth layer. 5. An interference filter as claimed in claim 4, wherein; the optical layer thickness of the first and second layers is 2.96*λo/4, the optical layer thickness of the third and fourth layers is 1.06*λo/4, the optical layer thickness of the N-1 layer is 2.24*λo/4, the optical layer thickness of the Nth layer is 0.84*λo/4, and the optical layer thickness of the remaining layers is λo/4. 6. An interference filter as claimed in claim 5, wherein said substrate is formed of glass, said high-refractive index layers are formed of zirconium dioxide, and said low-refractive index layers are formed of aluminum oxide. 7. An interference filter as claimed in claim 5, wherein said substrate has a refractive index of 1.52, said high-refractive index layers have a refractive index of 2.05, and said low-refractive index layers have a refractive index of 1.63. 8. An interference filter as claimed in claim 5, wherein the number of layers superimposed on said substrate is 20 to 40, preferably 30. 9. An interference filter for use in a copying machine as mounted on an optical path of light passing through an image-forming lens for preventing transmission of light having a predetermined wavelength range about a design wavelength, λo, said interference filter comprising: a substrate for carrying a plurality, N, of layers superimposed thereon; said layers including layers of high-refractive index elements arranged at odd-numbered places in order as counted from said substrate, and layers of low-refractive index elements arranged at even-numbered places in order as counted from said substrate; wherein: the first layer as counted from said substrate has an optical layer thickness greater than λo/2, the second layer as counted from said substrate has an optical layer thickness greater than λo/2, the third layer as counted from said substrate has an optical layer thickness greater than λo/4, the fourth layer as counted from said substrate has an optical layer thickness greater than λo/4, the fifth to N-2 layers as counted from said substrate have an optical layer thickness equal to λo/4, the N-1 layer as counted from said substrate has an optical layer thickness greater than λo/2, and the Nth layer as counted from said substrate has an optical layer thickness smaller than λo/4.
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