Polar coordinate laser pattern generator for fabrication of diffractive optical elements with arbitrary structure

Abstract

A precision laser pattern generator for writing arbitrary diffractive elements was developed as an alternative to Cartesian coordinate laser/electron-beam writers. This system allows for the fabrication of concentric continuous-relief and arbitrary binary patterns with minimum feature sizes of less than 0.6 microm and position accuracy of 0.1 microm over 300-mm substrates. Two resistless technologies of writing on chromium and on amorphous silicon films were developed and implemented. We investigated limit characteristics by writing special test structures. A 58-mm f/1.1 zone plate written directly is demonstrated at a lambda/50 rms wave-front error corresponding to a 0.06-microm pattern accuracy. Several examples of fabricated diffractive elements are presented.

The Efficiency of Optical Microstructures Formed on Molybdenum Films

“…Microstructures were formed at station of the laser record CLWS-200 [13][14] in the following sequence of technological operations: -a dusting of a thin film of molybdenum on a substrate; -formation of a test lattice by a local ablyation of a film under the influence of laser radiation. Optically smooth substrates from glass and fused quartz the size 50×50 of mm, 3 mm thick formed the basis.…”

The research of the properties of thin films of molybdenum to form the contact masks for diffractive optics elements

“…Patterns in the films formed on the laser writing station CLWS-200 [16][17][18]. Recording was conducted under the following conditions: operating wavelength of the laser radiation is 488 nm; maximum power supplied to the recording head 100 mW; record structure -concentric rings with a pitch of 3 μm and an outer radius of 3 mm; the magnitude of the power for each ring decreased from 100 % at the point of greatest radius to 0 in the centre with a step of 0.5 %.…”

Laser ablation of thin films of molybdenum for the fabrication of contact masks elements of diffractive optics with high resolution

“…A characteristic feature of the studies described in [1][2][3][4][5][6][7][8][9][10][11], is that the resistance to the subsequent chemical resistance increases for portions of film exposed to the laser radiation. In contrast to [1][2][3][4][5][6][7][8][9][10][11], we propose an approach based on evaporation (ablation) portions of the film exposed to laser radiation.…”

“…Thermochemical laser writing [1,2], the contact masks plays a decisive role for a wide range of [3][4][5][6][7][8][9] The methods of forming the microrelief diffractive optical elements. Currently, the widely used form metalized microrelief mask thin films of metals [1][2]5], in which during exposure to laser radiation is focused thermochemical conversion of the surface layer of the working material.…”

“…about 0.8 μm [10]. In this regard, the actual task is the development of technological methods for creating elements with high spatial resolution.On the basis of the above-described process sequence, for example, in [11], there has been an element size of 0.5 μm on the structure of the chromium films 50 nm thick inflicted thermal vacuum process substrates of optical glass.Patent [12] describes how to increase the resolution of the method of laser thermochemical oxidation film of titanium thickness of 3 -60 nm, deposited on the glass substrate.A characteristic feature of the studies described in [1][2][3][4][5][6][7][8][9][10][11], is that the resistance to the subsequent chemical resistance increases for portions of film exposed to the laser radiation. In contrast to [1][2][3][4][5][6][7][8][9][10][11], we propose an approach based on evaporation (ablation) portions of the film exposed to laser radiation.…”