Method for production of laser-induced damage images with special characteristics by creating damages of special space shape
AssigneeTroitski
InventorIgor Troitski
Life of this patent
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Abstract
A method for production of laser-induced damage images, which are able to change their optical characteristics depending on bopresight allocation and which are looked like iridescent images laying out white light incident upon them. These images are created by laser-induced damages of special space form. These damages are produced by creation of two areas (the first and the second) surrounding the pre-set points: the first area is essentially large than the second area, having form like desirable damage. The pulse laser radiation creates under critical electron density in the first area and initiates the breakdown in the second area.
Claims15
1 A method for production of laser-induced damages with special characteristics by creating damages of special space shape, comprising:
- production of images, which are able to change their optical characteristics depending on bopresight allocation and direction of light;
- production of images comprising etch points which can appear and disappear during all-round surveillance;
- production of multicolor images, which can have areas with different spectral characteristics.
2 A method in accordance with claim 1 wherein the said laser-induced damages are created by special space distribution of laser radiation in the areas of the pre-set points, comprising:
- division of an area of every pre-set point into two areas (the first area and the second area) so that the first area is essentially larger than the second area and it involves the second area;
- the second area has the form which is desirable for damage production;
- creation of under critical electron concentration inside the first area by the pulse laser radiation;
- creation of the breakdown inside the second area by the pulse laser radiation of energy, which exceeds the breakdown threshold by a negligible manner.
3 A method in accordance with claim 2 wherein the said laser-induced damages of spherical form without star structure are produced by an optical system focusing laser radiation into a small spherical spot and a large area containing the said small spot so that electron density of the spherical spot exceeds the breakdown threshold but electron density of the ambient space is smaller than the breakdown threshold density.
A method in accordance with claim 2 wherein the said laser-induced damages are created like patches of planes, so that they together with a flat surface of an article lay out white light incident upon them into spectrum.
5 A method in accordance with claim 2 wherein the iridescent laser-induced damages are produced so that every of them is an arrangement of separate cracks, which lay out white light incident upon them into spectrum.
6 A method in accordance with claim 2 wherein creation of the said two areas surrounding the pre-set points is produced by two independent (incoherent) laser beams.
7 A method in accordance with claim 2 wherein creation of different spectrum characteristics of different areas of the said laser-induced damages is controlled by orientation of laser-induced damages inside said areas.
8 A method in accordance with claim 2 wherein dynamical color variation of the said laser-induced damage images is produced by changing an angle of highlight radiation.
9 A method in accordance with claim 2 wherein the said laser-induced damages lay out white light incident upon them into spectrum by small diffraction gratings contained inside the damages.
10 A method in accordance with claim 9 wherein the said diffraction grating inside laser-induced damage is produced inside whatever transparent material using the breakdown phenomenon created by special space distribution of laser radiation so that laser energy increases breakdown threshold only in separate parallel planes.
11 A method in accordance with claim 10 wherein the said separate parallel planes are determined so that the distance between adjacent parallel planes is easily more than critical distance under which crash is happened.
12 A method in accordance with claim 11 the said distance between adjacent parallel planes and thereafter the said critical distance are reduced by using two areas surrounding the re-set point so that the diffraction grating area is placed inside the area, which essentially larger than diffraction grating area and which has under critical electron density.
13 A method in accordance with claim 9 wherein expansion of efficiency of the said diffraction grating inside laser-induced damage is produced by using the phenomenon of self-trapping (or self-focusing) of laser beam increasing the diffraction grating length.
14 A method in accordance with claim 9 wherein controlling brightness of laser-induced damages is produced by changing the depth of the area where gratings are created.
15 A method in accordance with claim 6 wherein the said each laser-induced damage is created by two coherent laser beams (the first and the second beams) generated by division of the basic power laser beam, comprising:
- division of the basic power laser beam into two laser beams (the first and the second beams) so that the first laser beam has the first energy level and the second laser beam has the second energy level;
- the first beam is “tightened” so its diameter is not larger than transversal sizes of the damage, which should be created;
- the first laser beam is directed in pre-determined transparent material area so that it passes through the pre-determined point;
- the first energy level of the first laser beam has enough grate value to create self-trapping phenomenon but a little smaller than breakdown threshold;
- the second laser beam has smaller power density than the first beam so it can not create self-trapping phenomenon and breakdown effect;
- total value of the first and the second beams is enough grate to create breakdown in the interference bands in the intersect place of the first and the second beams;
- the second beam is directed to self-trapping area of the first beam;
- the right brightness of the damage is controlled by second beam diameter;
- the first and the second beams are crossed under such angle so that distance between adjacent interference bands is larger than a minimum distance under which internal split is occurred.
Dependencies are inferred from the claim text.