Optical: systems and elements – Lens
Patent
1996-11-06
2000-06-13
Epps, Georgia
Optical: systems and elements
Lens
359743, G02B 300, G02B 308
Patent
active
060756527
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a convex-micro-granular surface structure which is contributory to attenuation of reflectance and/or enhancement of light collection. In further aspects, the present invention relates to a plastic lens structure for spectacle use, a process for manufacturing the same, a solar cell including a mechanism for improving the light collection efficiency, a technology for preventing surface reflection on the readout side of an optomagnetic recording medium, a photosensitive material which is chiefly used as a photographic film or printing paper, the light-receiving surface of which is provided with an antireflective function, a method and apparatus for preventing reflection of light within an irradiation light path in the fabrication of an electronic circuit including optical means, and associated products, among others.
BACKGROUND TECHNOLOGY
In diverse industrial fields, attenuation of reflection and/or enhancement of light collection efficiency has been required and a number of relevant proposals have been made to this day.
By way of illustration, spectacles are required to possess the function of correction of vision, the function to protect the eye from foreign matter and unwanted light rays, and fashionableness. Moreover, constant demands exist for ever lighter and thinner lenses, while colored lenses are valued for their fashionableness. Under the circumstances and prompted by advances in the development of polymer materials having high refractive indices, high transparency, dyeability, etc., the demand for plastic lenses has by now surpassed the demand for glass lenses. The performance characteristics required of a plastic lens are high transparency, high refractive index, light dispersion, reduced weight, safety, dyeability, and moldability, among others. At the same time, decreases in the quantity of reflected light on the lens surface and increases in the transmissivity of the lens are also important parameters. Generally the reflected light on the surface of the lens on one side amounts to 3-4% and the tendency is that the larger the refractive index of a lens, the greater is the quantity of reflected light generated. The means employed today for reducing the quantity of reflected light consists in building up a plurality of thin metal films to extinguish reflected light through the mutual interference of reflected light rays among the layers and it is common practice to construct 3-7 antireflective layers. While this construction of antireflective layers is carried out using a vacuum vapor deposition equipment, a very large equipment is required for mass processing of lenses and this entails not only a high initial investment but also a high running cost both of which lead to appreciation of the lens cost.
The quantity of reflected light across the interface between a transparent, smooth-surfaced material and the air can be decreased by varying the mean index of refraction between said surface and air continuously. This objective can be accomplished by forming a heterogeneous layer on the surface of a transparent material. The principle of this heterogeneous anti-reflective technology is now discussed. Assuming, for instance, that the surface has irregularities such as those illustrated in FIG. 9, the refractive index [nf(x)], where x represents the direction of depth of the surface layer, can be expressed by the following equation (1).
wherein ng represents the refractive index of glass, V(x) represents the volume of glass down to the depth x, n.sub.0 represents th e refractive index of air. Here, at the interface between air and the film and the interface between the film and the glass substrate, there is a discontinuous change in refractive index as illustrated in FIG. 10. writing the refractive indices at these points as n.sub.1 and n.sub.2, respectively, the index of reflection R of this layer can be expressed by the following equation. ##EQU1##
Assuming that, in this equation, n.sub.0 =1.0, n.sub.1 =1.1, n.sub.2 =1.477, ng=1.53, the lowest ref
REFERENCES:
patent: 4153654 (1979-05-01), Maffitt et al.
patent: 5189337 (1993-02-01), Endo et al.
Ono Kotaro
Sumida Kenji
Epps Georgia
Lucas Michael A
Washi Kosan Co., Ltd.
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