A ring laser goniometer was investigated in different applications of precision angle measurement, such as the calibration of optical polygons and optical encoders, external angle measurement of rotatin g objects and inertia l angle measurement by rotatio n of the goniometer itself. The results agree with standard methods of angle measurement to about 0,5 m rad (0,1 ). Further im provem ent in accuracy is expected mainly from the reduction of noise in the mechanical and electrical setup of the measurement system.

Equations previously derived for the volume and internal energy of a simple monatomic liquid, using approxlmate geometric theory, are used to calculate the specific heats Cv, Cp and volume V of liquid argon as a function of pressure and temperature. A Lennard-Jones 12-6 interatomic pair potential is used. The results are compared with the correspondmg experimental curves. The qualitative features of the (P, V ) isotherms are reasonably reproduced, and at high pressures the densities are within 25% of the experimental values. The agreement of the specific heats is poorer, although the correct order of magnitude is predicted by the theory.

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This paper presents an inertial system for railway track diagnostics. The key element of the system is a set of inertial measurement units (IMUs) based on MEMS gyros and accelerometers, which are mounted directly on the axle boxes (bearing covers) of the wheel pairs. The system made it possible to investigate how the car-track dynamic interaction affects measurements of geometrical deformations and to determine parameters, such as defects of rail treads.

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The main application of a ring laser gyroscope is navigation. It is currently the most widely used device for strapdown inertial navigation systems. However, it is also applicable for high-precision angle metrology systems. This paper discusses the properties of a laser dynamic goniometer (LDG) based on the ring laser gyroscope and designed for the calibration of optical polygons and digital angle converters, and for the measurement of angles between external mirrors (theodolite operating mode). We consider the main sources of uncertainty, such as the ring laser gyro bias due to an external magnetic field and the instability caused by the velocity of rotation along with applicable methods of their compensation. The reversal method providing separation of uncertainties of the LDG and the calibrated angle converter is analyzed in detail. The simplified cross-calibration method is also considered. The results of calibration of optical encoders of various designs—with and without their own rotors (on-axis and off-axis in Euramet terminology)—are presented. Some results of the dynamic goniometer for the measurement of angles between external mirrors are presented. It is shown that the LDG in this mode of operation demonstrates better accuracy than modern theodolites and total stations.

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