Method of laser marking a body of material having a thermal conductivity approximately equal to that of glass
First Claim
1. A method of providing a body of material having thermal conductivity approximately equal to that of glass with a sub-surface mark, said method comprising directing at a surface of the body a beam of laser radiation to which the material is substantially opaque, so as to cause beam energy to be absorbed at the surface of the material in an amount sufficient to produce localised stresses within the body at a location spaced from said surface without any detectable change at said surface, the localised stresses thus produced being normally invisible to the naked eye but capable of being rendered visible under polarized light.
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Accused Products
Abstract
A method of providing a body of material (14), having a thermal conductivity approximately equal to that of glass, with a sub-surface mark. A beam of laser radiation (12) to which the material (14) is substantially opaque is directed to surface of the body, so as to cause beam energy to be aborbed at the surface of the material in an amount sufficient to produce localised stresses within the body (14) at a location spaced from the surface without any detectable change at the surface, the localised stresses thus produced being normally invisible to the naked eye but capable of being rendered visible under polarised light.
127 Citations
15 Claims
- 1. A method of providing a body of material having thermal conductivity approximately equal to that of glass with a sub-surface mark, said method comprising directing at a surface of the body a beam of laser radiation to which the material is substantially opaque, so as to cause beam energy to be absorbed at the surface of the material in an amount sufficient to produce localised stresses within the body at a location spaced from said surface without any detectable change at said surface, the localised stresses thus produced being normally invisible to the naked eye but capable of being rendered visible under polarized light.
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14. A method of providing a body of glass with a subsurface mark, comprising directing at a surface of the glass body a beam of laser radiation to which the glass is substantially opaque, so as to cause beam energy to be absorbed at the surface of the glass body in an amount sufficient to produce localised stresses within the glass body at a location spaced from said surface without any detectable change at said surface, the localised stresses thus produced being normally invisible to the naked eye but capable of being rendered visible under polarised light.
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15. A method of providing a body of plastics material with a sub-surface mark, the plastics material having a thermal conductivity approximately equal to that of glass, said method comprising directing at a surface of the body a beam of laser radiation to which the plastics material is substantially opaque, so as to cause beam energy to be absorbed at the surface of the body in an amount sufficient to produce localised stresses within the body at a location spaced from said surface without any detectable change at said surface, the localised stresses thus produced being normally invisible to the naked eye but capable of being rendered visible under polarised light.
Specification