Patent ID: 8663754

Claim:
A method of pulsed laser deposition to produce a pattern on a medium, said medium being substantially transparent at a wavelength of said pulsed laser, said method comprising: generating pulsed laser beams from a pulsed laser source, wherein said pulsed laser source generates pulses at a repetition rate from about 100 kHz to 100 MHz; directing said pulsed laser beams through said medium and focusing said pulsed laser beams onto a target during scanning of said pulsed laser beams along a path in a scan direction, said target producing ejecta in response to an interaction of said target and said pulsed laser beams at said repetition rate; and accumulating at least a portion of said ejecta on said medium to form material deposits on said medium, and to form a spatial pattern having varying optical density that produces a visual effect of grayscale, wherein said interaction causes ejecta to expel sideways relative to said scan direction and to concentrate ejecta toward the periphery of the path of said pulsed beams such that the material deposits are formed with central low thickness portions bounded by immediately adjacent, thicker outer portions, wherein said medium and said target are spaced apart by a gap within about 100 μm, or are in direct physical contact, and the thickness of said deposits is controlled with said repetition rate and a scanning speed of said pulsed laser beams.