Electric heating – Metal heating – By arc
Reexamination Certificate
2001-07-03
2003-05-20
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
Reexamination Certificate
active
06566626
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to imprinting images in transparent media. More particularly it relates to method and apparatus for imprinting color images in transparent medium, and in particular in transparent light-sensitive glass.
BACKGROUND OF THE INVENTION
Colorless marking of images on or within glass is known. Description of a method and equipment for generating of colorless marks at or underneath glass surface with a laser beam, with energy density generated in its focus point sufficient to form an increased opacity area relative to the visible spectrum part in transparent material, can be found in U.S. Pat. Nos. 4,467,172 and 5,206,496.
In RU Pat. No. 2008288 a description of a technique of generating 3-dimensional patterns in glass, in which the pattern formation while retaining the transparency of the specimen surface is achieved by exceeding the threshold value of the volumetric glass breakdown while simultaneously displacing the specimen with respect to the focused laser beam. However, the patterns generated in the glass using the mentioned methods are colorless and are of low-contrast, which strongly impairs the product consumer's features and appeal.
Color patterns in porous glasses can be generated using the method described in U.S. Pat. No. 4,403,031, in which the liquid that fills the quartz glass pores and contains organic and metal compounds is colored due to photolytic reaction activated by irradiating it with light whose wavelength is in range between 230 to 400 nm.
According to the method described in European Patent application No. 98940718.4, colored three dimensional (3D) images can be generated in transparent porous glasses by focusing laser radiation of wave length of 1060 nm irradiated on the material contained within the pores, which is capable of irreversible color change under the action the optical breakdown factors and subsequent treatment (chemical, thermal, light or acoustical). In porous glasses light-sensitive components do not constitute a part of their chemical composition, but rather they are added to the substance, filling the pores. Moreover, the light transparency coefficient of these glasses is lower in comparison with normal glasses, because the porous glasses are, in reality, a multiphase substance. As a result the field of application of products with colored patterns in porous glasses is limited.
Alternatively the special features of light-sensitive glasses, including polychromatic glasses can be used to obtain color markings. Light-sensitive glasses include light-sensitive components that are a part of their chemical composition. As a result these glasses gain color under the action of actinic (UV, X-, &ggr;-) radiation with subsequent thermal treatment. For example, Stookey (U.S. Pat. No. 4,266,012) suggests a photo-process in which 3-8 colored micro-mosaic filters are designed from different shape polychromatic glass plates or 0.01-1.5 mm films.
In order to make use of the known correlation between light-sensitive glass color and actinic radiation exposure time for generating colored images in such glasses Luers developed a photo-process of generating a black & white negative (U.S. Pat. No. 4,302,235) and semi-transparent net patterns (U.S. Pat. No. 4,295,872).
A color-shaded pattern is obtained by light irradiation on polychromatic glass via a negative or different templates in the wave lengths range of 280 to 320 nm and with total intensity range of 0.4-2.4 Joule/cm
2
, and subsequent thermal treatment at a temperature between the transformation point (log &eegr;=13,4 P) and the glass softening point (log&eegr;=7,6 P).
Light-sensitive glasses or their more advances type—polychromatic glasses, which can be colored upon cyclic irradiation of UV radiation and mandatory thermal treatment, contain light-sensitive metals (e.g. Au, Ag) and light-sensitivity sensitizers, such as optical (e.g. CeO
2
) or thermal ones (e. g. SnO, Sb
2
O
3
). Numerous studies were dedicated to the compositions of light-sensitive glasses (e.g. U.S. Pat. Nos. 4,017,328, 4,057,408, 4,092,139, 4,134,747, and 4,328,299). In spite of a great number of known compositions their elaboration is being continued nowadays and is aimed at optimizing light-sensitive glass features needed to obtain the required color shades customized to a variety of purposes and the techniques of generating colored images.
For example, U.S. Pat. No. 5,078,771 describes compositions of polychromatic glasses, which are being synthesized and placed as a 0.1&mgr; layer at the surface of glass matrix during the course of ions exchange, taking into consideration the chemical composition of specifically adopted bath. Under the action of high-energy laser beam in the wavelength range of 200-300 nm digital or other visual information can be recorded and later developed by thermal treatment and etching in hydrofluoric acid. Such information carriers in a form of products with surface topography can be applied in electronics and computer technologies.
Description of similar technology of etching of parts made from light-sensitive glass in hydrofluoric acid, which were irradiated with UV—laser pulse radiation and underwent subsequent thermal treatment, can be found in U.S. Pat. No. 5,322,538. Products manufactured using this technology were offered for use in high-quality heads of printing devices.
In the coloring methods described in the above references colored information in light-sensitive glass is generated either in a form of marks (patterns) at the surface or penetrating from the surface to the material depth. Namely, these methods cannot be used for generating color patterns localized in light-sensitive glass volume and not related to the product surface.
Furthermore the methods described in the prior art utilize external UV radiation in order to acquire color images within the sample, and as a result there always exist traces of color going from the surface inwardly.
A main object of the present invention is to provide a method and apparatus for generating colored marks (patterns) localized in the volume of light-sensitive glass but not related to the product surface i.e. there is no contact of colored image with the surface of specimen.
BRIEF DESCRIPTION OF THE INVENTION
It is therefore thus provided, in accordance with a preferred embodiment of the present invention, a method for generating colored images of at least one of a plurality of colors within a light-sensitive glass sample that contains light-sensitive chemical components that acquire at least one of a plurality of colors in response to actinic radiation and subsequent heating to a temperature that causes color to appear, the method comprising:
providing pulsed laser beam source having a radiation off the range of ultraviolet spectrum;
providing a focusing device for focusing said pulsed laser beam at a predetermined focus point within the glass;
providing a displacing device for providing relative predetermined displacement between the focus point and the glass sample;
focusing the laser beam to a target location within the glass;
irradiating a plurality of pulses of the pulsed laser beam focused in the target location within the glass sample so as to generate a zone of increased opacity to the visible light at the target location and a resultant localized actinic radiation at that zone;
displacing the focus point of the laser beam and the glass sample relative to each other by the displacing device in a predetermined manner so as to produce a plurality of zones of increased opacity that form an image; and
heating of the sample to a temperature that causes color to appear at the zones of increased opacity.
Furthermore, in accordance with another preferred embodiment of the present invention, the method further comprises performing, after a first color was obtained at the zones of increased opacity at least one cycle of the following steps:
irradiating the pulsed radiation by focusing the laser beam within the sample in said zones of increased opacity to the visible light; and
perfo
Dmitriev Vladimir
Gaissinsky Grigory
Guletsky Nikolay
Kopelev Stella
Kopelev Victor
Heinrich Samuel M.
Laserglass Ltd.
Saltamar Innovations
Wertsberger Shalom
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