Optical: systems and elements – Light interference – Produced by coating or lamina
Reexamination Certificate
1999-11-30
2001-07-17
Chang, Audrey (Department: 2872)
Optical: systems and elements
Light interference
Produced by coating or lamina
C359S585000, C359S586000, C359S360000, C359S359000, C427S162000, C427S164000
Reexamination Certificate
active
06262847
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical element (mirror) making use of internal reflection, which is used in optical instruments (optical apparatus) such as cameras, copiers, printer exposure apparatuses and so on, and a method for producing the optical element.
2. Related Background Art
There have been proposals of optical members (plane mirrors and curved mirrors) of the internal reflection type in which light was incident to one surface of a transparent substrate and in which the light was reflected inside the substrate by a reflecting film formed on the other surface of the transparent substrate.
In general, ordinary mirrors of the internal reflection type used in optical instruments are those obtained by forming a reflecting film of metal such as Al (aluminum), Ag (silver), or the like having high reflectances in the visible light region, on a substrate and then laying a protective film of a dielectric film or a metal film thereon or a protective film of a coating film thereon.
The internal reflection type mirrors of Al according to the conventional technology, however, were apt to have low reflectances throughout the entire wavelength range and particularly in the long wavelength region. Further, the Ag films had relatively high spectral reflectances, but were apt to decrease the reflectances in the short wavelength region when subjected to an ion bombardment cleaning operation or the like for enhancing adhesion. A photographing optical system using a lot of such internal reflection type mirrors had a problem that transmitted light thereby was light of colored spectral characteristics.
Also, the protective film of the coating film required a new device or jig separate from an evaporation system used for formation of the metal film. This posed problems that the production steps became complex and that the cost of the production apparatus was high.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an optical element that can be produced at low cost and simply and that has high reflectances, and a method for producing the optical element.
A further object of the present invention is to provide an optical system having the optical element with high reflectances.
An optical element of the present invention comprises a transparent substrate, an undercoat formed on the substrate, and a reflective film formed on the undercoat. The undercoat includes and the undercoat comprises dielectric multilayered films, each film having a thickness in the range of 50 to 100 nm.
A method for producing an optical element according to the present invention comprises a step of forming an undercoat on a transparent substrate and a step of forming a reflective film on the undercoat, and the steps are carried out continuously without heating the substrate.
An optical system of the present invention comprises the optical element of the present invention or the optical element produced by the method for producing the optical element according to the present invention.
REFERENCES:
patent: 5267081 (1993-11-01), Pein
patent: 5582879 (1996-12-01), Fujimura et al.
Tsukamoto Mayumi
Tsukamoto Seitoku
Canon Kabushiki Kaisha
Chang Audrey
Fitzpatrick ,Cella, Harper & Scinto
Tsukamoto Mayumi
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