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Temperature stabilization of semiconductor lasers for direct measurement of index of refraction of air
Matoušek, Vít
Laser interferometers are even more precise distance measurement devices with resolution in nanometer or sub-nanometer region. If interferometric measurements are carried out under atmospheric conditions (usual situation in industry), they measure optical path length of an unknown distance instead of its true geometrical value. It is caused by an index of refraction of air that introduces a multiplicative constant to measured results. If we want to obtain correct values, the knowledge of the index of refraction is necessary. Generally, the index of refraction can be measured by two ways: indirectly or directly. The first of them is based on parametric analysis of atmospheric properties as: relative humidity, pressure, temperature, concentration of CO.sub.2./sub. etc. Values of these parameters are processed then by Edlen formulas with 10.sup.-7./sup. order [1]. The direct methods are more precise then Edlen formulas (more than 10.sup.-7./sup.) but their practical implementation is more difficult. Devices that directly measure the index of refraction are called refractometers.
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Temperature stabilization of semiconductor lasers for direct measurement of index of refraction of air
Matoušek, Vít
Laser interferometers are even more precise distance measurement devices with resolution in nanometer or sub-nanometer region. If interferometric measurements are carried out under atmospheric conditions (usual situation in industry), they measure optical path length of an unknown distance instead of its true geometrical value. It is caused by an index of refraction of air that introduces a multiplicative constant to measured results. If we want to obtain correct values, the knowledge of the index of refraction is necessary. Generally, the index of refraction can be measured by two ways: indirectly or directly. The first of them is based on parametric analysis of atmospheric properties as: relative humidity, pressure, temperature, concentration of CO.sub.2./sub. etc. Values of these parameters are processed then by Edlén formulas with 10.sup.-7./sup. order [1]. The direct methods are more precise then Edlén formulas (more than 10.sup.-7./sup.) but their practical implementation is more difficult. Devices that directly measure the index of refraction are called refractometers.
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Laser head with VCSEL laser diode
Mikel, Břetislav ; Urban, F.
We describe a new laser head with Vertical Cavity Surface Emitting Laser (VCSEL) diode. The VCSEL lasers at 760 nm with mode-hop free tuning range above 1 nm are affordable now. The VCSEL's are fabricated as circulary-symetric lasers; the circular aperture is of particular value as it implies a circular beam profile. The linewidth and the optical noise of the VCSEL laser diode depend on the stability of the current source controller and on the quality temperature control system. We developed a digital temperature control system with temperature stability below 1 mK and high stability current source conttroller.
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Construction of laser source for precision measurements
Mikel, Břetislav ; Urban, F. ; Číp, Ondřej
We describe a new laser head with Vertical Cavity Surface Emitting Laser (VCSEL) diode. The VCSEL lasers at 760 nm with mode-hop free tuning range above 1 nm are affordable now. The VCSEL's are fabricated as circulary-symetric lasers; the circular aperture is of particular value as it implies a circular beam profile. The linewidth and the optical noise of the VCSEL laser diode depend on the stability of the current source controller and on the quality temperature control system. We developed a digital temperature control system with temperature stability below 1 mK and high stability current source controller.
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New method for direct measurement of refraction index of air with He-Ne lasers
Matoušek, Vít ; Číp, Ondřej
Interferometer methods are used for the high accuracy measurement of distance by specifying the measurement of the air index, since the measurement of the refraction index of air is in atmosphere, the refraction index of air is dependant upon temperature, pressure and humidity. For the measurement of the refraction index of air, Eden's formula is usually used. The formula depends upon the atmospheric values and the CO2 concentration.
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Vláknové mřížky pro zvýšení stability polovodičových laserů
Mikel, Břetislav ; Číp, Ondřej
The industrial production of Vertical Cavity Surface Emittíng Laser (VCSEL) diodes started several years ago. They have a wide range of applications in laser interferometry and spectroscopy. At present VCSELs become very attractive in optical communications in Wavelength Division Multiplexing (WDM) systems. The influence of the external optical feedback on spectral characteristics of VCSELs has been studied. At present the most interesting solution of this external feedback is to use an external fiber with fíber grating. Thanks to advances in technology of fabrication of fiber gratings they can be used as the external cavity for edge emitting laser diodes and as well as for VCSELs. Study of linewidth improvement, frequency stability, and mechanical stability are growing in importance in connection with fiber gratings
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