An extremely small optical displacement sensor using a laser diode integrated with a microlens and based on the composite cavity principle was constructed. The microlaser displacementmeter has been developed using this optical sensor. The measuring resolution of the displacement is less than 0.01 µm and it can detect very low velocities of less than 5 µm/s. The optical sensor is very small, 800 µm × 900 µm. The microlaser displacementmeter shows good linearity between relative displacement and output signal.
Laser differential interferometry is now widely used for the study of fast dynamic phenomena. The obtained interferograms provide the important data for the calculation of threshold strength in the materials under shock loading and allows to determine the beginning of their destruction. In the paper we analyse the procedure of the interferogram formation in such interferometer. The distribution of the particle velocities of the material under shock loading causes the quasi-monochromatic character of the interfering waves. In general case it occurred the result of interference of two...
This paper proposes a contactless displacement measurement system based on a temperature compensated light-to-frequency ( L / F ) converter. The optical displacement sensor is represented by the L / F converter excited by a LASER beam. To compensate the temperature drift error of the displacement sensor, an additional temperature measurement system based on a temperature transducer is required. The processing of the data delivered by the sensors is on-line performed using a neural algorithm implemented on a Digital Signal Processor. The Artificial Neural Network architecture used in the...
A measuring principle for the determination of absolute distance and thickness values is proposed. Based on the combination of laser interferometry (Michelson type) and Doppler technique the new developed devices include laser sources showing a short coherence length. This contributions aims to describe some preliminary experiments and to point out some of the main advantages of short coherence interferometry, their non-destructive and non-contact behaviour and the possibilities for self-calibration. The measurement results are mainly independent of the objects´ position and movement....
The wide scale inspection of extended technical components with respect to the recognition of typical surface features (shape, texture, roughness) needs the combined application of different measurement techniques together with new tools for the consistent analysis and description of the measuring results. The new concept of scalable topometry meets the demands of wide scale surface topometry. Controlled by the evaluation of scale-independent surface features based on fractal geometry, different measurement techniques with subsequent lateral and depth resolution are applied to the surface....
Monolithic Nd:YAG lasers are appropriate coherent light sources for measurement purposes. Measurement restrictions can be caused by laser signal instability. We discuss the influence of pump source, temperature and competing laser oscillations on signal properties of lasers with a linear resonator configuration and analyze some passive stabilization precautions. We conclude linear monolithic Nd:YAG lasers can provide high beat frequency stabilities which are comparable to optical stabilities of free-running nonplanar monolithic ring lasers.
Reflection ellipsometry is a proven optical measurement method often used to measure film thicknesses. Classical ellipsometers use an unfocused measurement beam, which causes a low lateral resolution in the order of 1 mm. To determine microstructures ellipsometrically (e.g. in the semiconductor industry), an improved lateral resolution in the order of micrometers is essential. We discuss the problems of focusing ellipsometry, occurring when a reflection ellipsometer is used to measure surface characteristics (topography, material). Different measurement setups are analyzed and compared....
Nano-CMM is required to evaluate tolerance and dimension of the component parts of micromachines by coordinate measurement of submillimeters size 3-D shapes. This paper discusses a micro-probe technique for the nano-CMM, the so-called laser trapping micro-probe. The principle to detect a three dimensional position is based on the nature of an optically trapped particle and interferometer method. An optically trapped silica particle in air is used as a micro-probe sphere. Practical positional detection method is established based on experimental analysis of fringe intensity changes while a...
Spectroscopic methods have been for years widely used in analytical laboratories. However, their application in industrial and environmental practice has been up to now relatively limited because of the high costs of spectrometric instrumentation. This is only recently that the advances of micro- and optoelectronics have made feasible integrated implementation of some spectrometric techniques and the design of low-cost spectrometers for industrial applications. The integration implies a significant reduction of instruments precision – mainly due to miniaturisation. This loss, however, may be...
The paper considers some theoretical problems, concerned with automatic correction of systematic errors, occurring in determination of real values of brightness under a nonlinear transfer function of a photoelectric transducer. A version of a solution for the problem of linearization of a general transfer function of digital brightness meters is given. The paper describes a procedure of a linearization, based on the functional-algorithmic methods, grounded on application of quantities substitution formulas. The redundant measurements equations are derived. It is shown, that it is necessary...