Features of thermal trace forming by thermochemical circular laser writing in chromium films on glass (quartz)
substrates are considered on the basis of thermal equation system solution. Linear (thermal parameters do not
dependence on temperature) and nonlinear (thermal parameters dependence on temperature) models are considered. It is
showed that linear model is enough for thermal trace broads consideration. Calculation of thermal field is provided for
wide range of linear scanning velocities (from 1.2 up to 9.4 m/sec). Dynamics of chromium film heating when laser
beam is switched on is researched. Difference of the thermal trace form in switching on area and switching off area is
showed. Also structures like chess board are synthesized for experimental investigation. Influence of thermal processes
inertness on the broadband image parameters is considered on such samples experimentally. Recommendations for
experimental selection of writing power have been done.
The results of scanning method research for testing of diffraction optical elements are shown in this paper. The diffraction efficiency of a specimen of diffraction optical element (Fresnel lens) was measured by the proposed scanning method and by direct (integral) method. Measured data are compared and analyzed. Results of efficiency measurement of diffraction optical element, that produces non-spherical wavefront transformation, are presented and discussed. The parameters of the fulfilled phase profile for these diffractive optical elements are evaluated.
Proc. SPIE. 3633, Diffractive and Holographic Technologies, Systems, and Spatial Light Modulators VI
KEYWORDS: Quartz, Glasses, Silver, Manufacturing, Photoresist materials, Transmittance, Modulation transfer functions, Fresnel lenses, Global system for mobile communications, Laser systems engineering
The perspective opportunity to fabricate gray-scale masks was given LDW-glasses (LDW--Laser Direct Writing) from Canyon Materials, Inc. LDW-glass blanks contain a large number density of coloring specks of silver in a surface glass layer. A focused laser beam is used to heat erase these coloring specks. Experiments on the influence of laser radiation on LDW-glasses was carried out using a circular laser writing system. The transmittance value from the blank of 0.1 - 5% up to 70 - 80% depending on laser beam power is obtained with the current write scheme. Results of research of LDW-glasses behavior in a wide range of laser beam scanning speeds are described. Laser pattern generation in LDW-glass including the spatial resolution is discussed. The technology of fabrication of continuous-phase diffractive elements was tested by making exemplary Fresnel lenses. Total 80% efficiency for quartz Fresnel lenses with minimal zone width of 8 micrometers was readily achieved in the preliminary experiments.
The application of continuous-tone photomasks for fabrication of diffractive optical elements with a deep phase relief is explored. Results of computer simulation for technological process are reported and compared with experiment. The experimental testing of offered technique was carried out on thick AZ4562 photoresist layers. The possibility of deep phase relief fabrication has been proven. The application of the new technique to fabrication of multiorder diffractive elements is discussed.