In this paper we present the DAVLL (Dichroic Atomic Vapor Laser Lock) signals detection method for laser frequency stabilization which has been improved by synchronous detection system based on the surface-stabilized ferroelectric liquid crystal (SSFLC). The SSFLC cell is a polarization switch and quarter waveplate component and it replaces the well-known two-photodiode detection configuration known as the balanced polarimeter. The presented polarization switching dichroic atomic vapor laser lock technique (PSDAVLL) was practically used in VCSEL-based frequency stabilization system with vapor isotopes (85,87Rb) rubidium cell. The applied PSDAVLL method has allowed us to obtain a frequency stability of 2.7 × 10−9 and a reproducibility of 1.2 × 10−8, with a dynamic range ratio (DNR) of detected signals of around 81.4 dB, what is 9.6 dB better than obtained in the balanced polarimeter configuration. The described PSDAVLL technique was compared with 3-f (on the 3rd harmonic) and passive frequency stabilization methods. Additionally, the presented setup consists only one-photodiode detection path what reduces parasitic phenomena like offsets between photodiode amplifiers, amplifier gain changes due to ambient conditions, aging effects of electronic components etc. as a consequence leads to better frequency reproducibility, stabilization accuracy and less detection system sensitivity to ambient condition changes.
In the paper we present the prototype of a straightness measuring device that uses a frequency stabilized Zeeman He-Ne laser. The He-Ne laser line is split by Zeeman effect into two circularly polarized laser beams. The frequency of the radiations differ of 1,2 MHz. The surface stabilized ferroelectric liquid crystal cell is used to stabilize the laser frequency. As the result of the laser frequency stabilization the power of both radiation is equal. The circular polarizations of two laser beams are converted into two linear polarizations perpendicular to each other. The two laser beams pass close to the measured axis. Along the axis the analyzing probe is moved. The analyzing probe changes the ratio of the power of the horizontal to the vertical polarization. This ratio is analyzed by the receiver composed of the ferroelectric liquid crystal switcher, the polarizer and the detector. The straightness of 2 m long optical bench was measured with this techniques. The resolution of 0,1 μm and the accuracy of 0.5 μm were obtained. The accuracy of presented technique is not so good as in the methods using laser interferometer but is comparable with methods using PSD, quadrant detectors or CCD at the same time offering bigger resolution.
In the report the arrangements of laser interferometers for machine history are presented; the laser interferometer LSP30 for investigation of geometry of machine tools, the setup for inspection of ball screw and laser liner for CNC machine. Outstanding feature of the interferometers is the stabilization system of laser frequency using surface stabilized ferroelectric liquid cells (SSFLC).
The results of investigation of saturation spectrum of iodine 127I2 hyperfine transitions for 543 nm HeNe laser radiation are presented in paper. Commercially available internal mirror green HeNe laser tube emitting at 543.5 nm and short external absorption cell were used in investigations. The 19 absorption components were observed, the parameters of obtained components can be suitable for frequency stabilization of 543 nm HeNe laser.
The results of mode spectrum investigations of commercial internal mirrors 543 nm HeNe laser are presented in this paper. Measurements of the laser Zeeman frequency were done for 543 nm HeNe laser tube placed in longitudinal magnetic field. Obtained results were applied for frequency stabilization of 543 nm HeNe commercial laser.
In this paper we are presenting the prototype of laser measuring system -- namely laser liner -- for Computer Numerical Control (CNC} machine tools and for Coordinate Measuring Machines (CMM). The laser liner is an innovatory arrangement of one frequency interferometer. The two-mode HeNe laser is used as a source of radiation whereas the surface stabilized ferroelectric liquid crystal cell (SSFLCC) for stabilization of the laser frequency. Small dimensions of the arrangements facilitate mounting of the interferometer on machine tools. Worked out advanced correction procedure of length of light wave compensates in real time the influence of parameters of atmosphere on the length of laser radiation. Another possible thing is compensation of thermal expansion of a material.
In the following paper we describe arrangements of laser interferometer for investigation of screws and for inspection of ball screws. We have constructed two of them, namely: the technological setup for investigations of screw in process of production and the ball screw inspection setup. The former one is used to measure the pitch of screws. The data gathered during measurement is used to calculate the parameters for grinding machine. The later setup is used for testing parameters of complete ball screws. The software supporting this setup makes calculation of parameters of tested ball screw and creation of reports possible. Additionally, the inspection setup is the one that the torque measuring arrangements have been integrated on. Both the arrangements and the software allow for measurements of all parameters during movement of nut in full travel length of the ball screw and make charts and reports.
The calibration system used for measurements of the frequency characteristics of 633 nm He-Ne lasers light is presented in the paper. The system consists of four blocks: the iodine stabilized He-Ne at 633 nm laser frequency standard, optoelectronic unit, microprocessor system and PC compatible computer. The presented system was applied for measurements of the frequency characteristics of the frequency stabilized He-Ne lasers used in the interferometric systems. The analysis of the obtained results is discussed in paper.
The paper describes the application of a Surface-Stabilized Ferroelectric Liquid Crystal (SSFLC) cell as a polarization switch in a frequency stabilization system of a Zeeman laser interferometer. The FLC cell is used as a field-controlled (lambda) /4 plate in which the optic axis can rapidly alternate between two positions, thereby alternatively switching either of two orthogonal radiations into the same measuring channel. The high switching speed of the FLC is here a key feature as it allows several thousand such calibration measurements to be performed in a second.
The laser interferometers are intended for high-precision measurement of distances and displacements. The calibration equipment for the definition of real meaning of the laser radiation wavelength and investigation of wavelength stability and reproducibility of the laser radiation in the laser interferometers is presented in paper. The laser radiation frequency was measured with the heterodyne method using the developed laser frequency iodine standard 633 nm. The system was used for calibration the frequency of the He-Ne Zeeman laser used in the two frequency laser interferometer.
The Zeeman He-Ne laser frequency stabilization system using a surface stabilized ferroelectric liquid crystal cell for polarization switching in the frequency stabilization loop is presented. Our experiments showed that two circularly polarized laser beams with on opposite sense of circularity can be switched up to 3.7 kHz rate. No additional optical components (the quarterwave and halfwave plates) were needed in switching setup. During three hours of operation the long time stability of the laser frequency of 3 multiplied by 10-8 was achieved. The laser stabilization system is suitable for the two frequency interferometer setups.
The two frequency laser interferometer for the angle and straightness measurements is presented. The principles of the operation of this laser system is described. The system consists of the laser head, optical elements, meteo station and PC computer. The construction of the main elements of the system are discussed. The parameters of the angle and straightness measurements are presented and compared to the other systems.
The influence of the magnetic field on Zeeman frequency of the He-Ne laser is presented in this paper. The new method of frequency stabilization of He-Ne laser is proposed. The optimization procedure for obtaining optimum discrimination curve of the He-Ne laser is described.
The two frequency laser interferometer, using frequency stabilized HeNe laser 0.63 micrometers , is presented in this paper. The system consists of a laser head, meteo station, and measurement display. The laser system fundamentally measures linear displacement (distance) but can also measure velocity and angle. The resolution and the accuracy of measurements are comparable with parameters of lasers systems produced by Hewlett-Packard 5526A and Spindler & Hoyer ZLI 150.
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