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Měření čistoty jódu v absorpčních kyvetách pro frekvenční stabilizaci laserů
Hrabina, Jan ; Petrů, František ; Jedlička, Petr ; Číp, Ondřej ; Lazar, Josef
In the contribution we present a system for measurement of iodine purity by means excitation of a selected strong transition, measurement of induced fluorescence and evaluation by the Stern-Volmer formula. The arrangement is based on a pumping Ar-ion laser tuned to the transition of interest but its linewidth far exceeds the transition. Frequency noise of the laser is effectivelly reduced by monitoring the fluorescence in a second, reference iodine cell and together with monitoring of the laser power enables cancelation of the frequency noise influence which generates errors by demodulating on the absorption profile. The level of the scattered light is subtracted as well. All the measured data are digitally processed and the experiment is fully computer controlled.
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New trends in the metrology of geometrical quantities
Lazar, Josef
The contribution deals with an overview of trends in modern fundamental dimensional metrology. This is since the introduction of the definition of metre derived from the vacuum speed of light the domain of laser optics and interferometry. The fundamental etalons of length are highly stable optical oscillators – lasers and the primary measurements of lengths are performed by interferometers. This overview covers the newest results of development of stabilized lasers and interferometry of high resolution in the sub-nanometre range especially concerning the results achieved at the Department of Coherence Optics of the Institute of Scientific Instruments of the ASCR in this field.
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Semiconductor lasers with high coherence and their application, activities of the Coherence Optics Department in ISI, ASCR
Lazar, Josef
Pracoviště oddělení Koherenční optiky svými aktivitami navazuje na tradici výzkumu a vývoje v oblasti laserů s vysokou koherencí a jejich aplikaci především pro metrologické účely. Tým Ing. Františka Petrů, DrSc. vyvinul první plynový laser v tehdejší ČSSR a následně dovedl technologii He-Ne laserů k vysoké dokonalosti. Ve svém úsilí se soustředil na frekvenčně stabilizované lasery pro laserovou interferometrii a následně v souvislosti s definicí jednotky délky prostřednictvím rychlosti šíření světla ve vakuu též na konstrukci laseru - primárního etalonu délky, resp. optické frekvence.295 The workplace of the Coherence Optics Department continues in the tradition of the research and development in the area of lasers with high coherence and their application especially for metrological purposes. The team of Ing. František Petrů, DrSc, developed first gaseous laser in the former CSSR and then led the technology of He-Ne lasers to highest perfection. It focused its striving to the frequency-stabilised lasers for laser interferometry and then, in correspondence with the definition of the unit of length by means of light propagation in vacuum, also to the construction of a laser - primary length, i.e. optical frequency etalon.
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Measurements of Residual Reflectivity and Wavelength of Coated Laser Diodes
Růžička, Bohdan ; Lazar, Josef ; Wilfert, O.
This contribution presents experimental results obtained by deposition of double-layer system made by means of electron-beam vacuum evaporation technique. We oriented our effort to short-wavelength 633 - 635 nm laser diodes. These devices are emitting close to the wavelength of traditional He-Ne lasers with an intention to use them in extended-cavity laser design for metrological purposes. The resulting reflectivities were evaluated by measuring a testing plate of GaAs and by measuring a "modulation depth" of a coated diode emission spectra. Our best results were reflectivities well below 10 -4 and the repeatibility of the deposition process in a range not exceeding 2x10 -4 .
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Iodine stabilized He-Ne laser for testing of laser interferometers
Petrů, František ; Lazar, Josef ; Zemánek, Pavel
The iodine-stabilized He-Ne lasers are the wavelength standard for metrology of lengths in mechanical engineering and microelectronics today. The high accuracy of the frequency of this standard predetermines this laser to be the fundamental etalon for laser interferometry. In the contribution, the basic properties of iodine-stabilized He-Ne lasers designed for the wavelength calibration of lasers for laser interferometry are discussed. In addition, some measurements of the vacuum wavelength of the single-frequency lasers of a novel type stabilized to the so called central maximum of the output power used as a source of laser radiation in the interference measuring system LOS are presented.
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Laser Optics and Technology in the Institute of Scientific Instruments of AS CR Brno
Petrů, František ; Pokorný, Pavel ; Lazar, Josef ; Stejskal, Alois ; Zemánek, Pavel
Research and development is oriented to new principles of frequency stabilisation using various physical phenomena. In this field special types of frequency stabilised lasers including He-Ne iodine-stabilised laser etalons at 633 nm were built. For this purpose the technologies of special laser tubes and absorption cells were developed. High-sensitive electronic systems for frequency stabilisation were designed and constructed and computer based measurement evaluation technique was developed. An important role among our activities plays thin film deposition technology, i.e. design of interference filters and production of individual pieces or small batches of elements according to specifications. Optical multilayers are produced by electron beam evaporation.
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Řídící systém pro absolutní interferometrii s plynule přeladitelným polovodičovým laserem
Mikel, Břetislav ; Číp, Ondřej ; Lazar, Josef
In the work, we oriented to development of the absolute distance interferometer with narrow-linewidth tunable VCSEL laser (Vertical-Cavity Surface-Emitting Laser) at 760 nm and a wavelength-scanning interferometry technique improved by an amplitudě division of interference fringe. We built a high precision current source with respect to high sensitivity of the VCSEL laser diodes. An operating temperature of the VCSEL laser housed in a specially designed copper mount is stabilized below l mK by a fast digital temperature controller. With respect to a highsensitivity of the emitted wavelength to the injection current fluctuation, we provided the stabilization of laser frequency by means of an electronic frequency lock to modes of the Fabry-Perot glass etalon. The PC controls the scanning process, so that, after l nm scan of the wavelength we obtains records of coursed interference fringes and Fabry-Perot resonance modes at the same time
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