Papers by Frantisek Prochaska
Journal of Instrumentation, 2022
This work presents the development of the production process of individual parts of the Fabry-Per... more This work presents the development of the production process of individual parts of the Fabry-Perot type laser resonator. It describes the acquired knowledge in the field of production of very precise optical standards, cavities, and lenses. In addition, it describes the measurement methods used in production. The work is intended for industry and science.
Applied Optics, 2022
The evaluation of optical surface defects is an integral part of the realization of precise optic... more The evaluation of optical surface defects is an integral part of the realization of precise optical elements. In addition to the traditionally used visual inspection procedures based on MIL-O-13830A, procedures based on ISO standards, which underwent some changes in 2017, are coming to the forefront. One of these changes was the omission of equivalent radiometric sizes and their replacement by geometric dimensions. This paper focuses just on the analysis of the impact of this change on the values of specifications defining the requirements on the scratch and dig quality of optical elements. Among other things, this presents a possible way to correct specification classes based on the statistical processing of a set of parameters of imperfections detected on optical element surfaces, which have been realized in the TOPTEC Centre.
Applied Sciences, 2020
Due to the increasing demands on the quality of solid-state laser active media production based o... more Due to the increasing demands on the quality of solid-state laser active media production based on yttrium aluminum garnet Y3Al5O12 in the form of rods with precisely machined faces, the possibilities of applying subaperture 3D corrective polishing in this segment of optical production were studied. For the considered laser rod diameters of up to 10 mm, the corrective process had to be optimized to achieve a stable, suitably shaped tool influence function at the full width at half maximum of approximately 1.5 mm, enabling 3D shape corrections with sufficient lateral resolution. For this purpose, a number of experiments were performed using both tools based on a flexible elastic membrane inflated by compressed air and tools with a viscoelastic head, and the effect of the tool-polished surface interaction was studied and analyzed.
Applied Optics, 2021
Metal mirrors for precise optical applications are commonly fabricated by coating of a metal base... more Metal mirrors for precise optical applications are commonly fabricated by coating of a metal base substrate with a nickel-phosphorus alloy (NiP). The NiP layer is then processed by precision diamond turning and polishing to obtain a high-quality mirror surface. In this work, Ti-6Al-4V samples that were made by additive manufacturing, also called 3D printing, were used as a base for the development of metal mirrors. The additively manufactured samples were electroplated with a NiP coating and machined using single-point diamond turning (SPDT) to obtain a flat mirror with optical quality and low form error surface. The periodic structure of the SPDT toolmark was then removed by polishing postprocessing. Polishing optimization was first performed on NiP-coated aluminum test samples to find an optimal polishing setup. Based on this optimization, postprocessing of titanium samples was carried out by pitch polishing in combination with 1, 0.25, and 0.1 µ m diamond slurries. Using this pol...
Optical Engineering, 2019
Abstract. We focus on the subaperture polishing tool concept development for suppressing midspati... more Abstract. We focus on the subaperture polishing tool concept development for suppressing midspatial frequencies (MSF) arising from computer numerical control machining of aspherical optical surfaces. The selective effect in the MSF range is achieved by setting the tool viscoelastic properties so that rigidity increases in the frequency-domain generated by the rotational tool movement over the aspheric surface with the MSF while the tool remains flexible in the lower frequency range associated with tool radial direction movement. The mechanism of MSF removal is discussed in detail, including in terms of elasticity module frequency dependences, and is also experimentally verified. In order to monitor and optimize viscoelastic properties, especially in regard to frequency dependences, the dynamic mechanical analysis method has been developed and applied and is presented in the paper as well.
Optics and Measurement Conference 2014, 2015
Chromatic distortion represents a limit parameter for many optical systems. For telescope objecti... more Chromatic distortion represents a limit parameter for many optical systems. For telescope objectives low chromatic aberration is especially important. The choice of appropriate materials is therefore crucial for the production of optical elements. The S-FPL-53 glass produced by Ohara Corporation is a readily available material with low dispersion. Its high Abbe number indicates low achromatism, therefore it is used in all the above-mentioned designs to achieve good correction. On the other hand, this fluorite glass is quite soft and has a high thermal expansion coefficient, so it is really difficult to polish. In this paper possible solutions to problems related to polishing aspherical lenses applying CNC technology and to polishing spherical lenses applying classical technology are discussed. By combining various conditions it is possible to achieve required roughness and shape of the lens surface.
SPIE Proceedings, 2015
We have realized an optical design of air space doublet of 100 mm clear aperture and 520 mm focal... more We have realized an optical design of air space doublet of 100 mm clear aperture and 520 mm focal length that is optimized with respect to a quality of wavefront error better than 0.07 λ RMS for on-axis imaging at wavelengths of 633 nm and 450 nm. To minimize optical aberrations we have designed one of the four surfaces to be an aspherical. Based on a tolerance analyses those take into account planned spherical and aspherical technologies for surfaces realization and measurement equipment we have realized the doublet. In the paper there is described a technique of the optical design, tolerance analysis, technique of objective realization and results of the optical elements realization.
EPJ Web of Conferences, 2013
The aim of this article is optical surfaces polishing on the 6-axis computer-controlled (CCM) mac... more The aim of this article is optical surfaces polishing on the 6-axis computer-controlled (CCM) machine Optotech MCP 250 CNC using FEM technology, which is suitable for aspheric elements polishing. The main attention is dedicated to the choice and to the precise adjustment of major process parameters. The possibility of usage the multi wave interferometer Luphoscan as a data source for the2D surface correction is solved too.
Optics and Measurement Conference 2014, 2015
In recent times, resin bond grinding wheels have often been used for the precise grinding of asph... more In recent times, resin bond grinding wheels have often been used for the precise grinding of aspheric surfaces. In this paper, the influence of changes in the circumferential speed of the resin bond grinding wheel on the microroughness of the produced surface and also on the volume of the structures and the scratches is presented. The article also discusses how the cutting wear of the tool affects the surface quality and shows the correlation between the circumferential speed and the rate of degradation of the resin bond grinding wheel. A circumferential speed interval from 12 m/s to 24 m/s was investigated and the effect of tool degradation was observed at 1.9-hour intervals. The results of the experiment show that the optimal circumferential speed of the tool lies around 20 m/s. At this speed, the tool produces a perfectly polishable surface and tool degradation is minimized.
Optical Engineering, 2014
ABSTRACT The aim of this work was an investigation of surface microroughness and shape accuracy a... more ABSTRACT The aim of this work was an investigation of surface microroughness and shape accuracy achieved on an aspheric lens by subaperture computer numeric control (CNC) polishing. Different optical substrates were polished (OHARA S-LAH 58, SF4, ZERODUR) using a POLITEX (TM) polishing pad, synthetic pitch, and the natural optical pitch. Surface roughness was measured by light interferometer. The best results were achieved on the S-LAH58 glass and the ZERODUR T using the natural optical pitch. In the case of SF4 glass, the natural optical pitch showed a tendency to scratch the surface. Experiments also indicated a problem in surface form deterioration when using the natural optical pitch, regardless of the type of optical material. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)
Fuel, 2010
This work deals with an evaluating of the storage stability of light cycle oil (LCO) which is pro... more This work deals with an evaluating of the storage stability of light cycle oil (LCO) which is produced by a fluid catalytic cracking technology. The LCO was aged according to two methods ASTM D2274 and ASTM D4625. The first test simulates an intensive oxidation stress and the second method is suitable for a longtime storage stability testing. The acid number, the iodine number, the carbon residue and the insolubles amount were chosen as parameters for the evaluation of the stability in both tests. Only the insolubles amount and the carbon residue varied (increased) during both tests. Four types of antioxidants were used as the oxidation inhibitors but no distinct effect on the oxidation stability of the LCO was observed.
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Papers by Frantisek Prochaska