1,720,987 research outputs found
High-performance front-end electronics for frequency-modulated continuous-wave interferometers
No full textA high-performance analog electronic circuit for processing the signal from an absolute distance meter based on a frequency-modulated continuous-wave (FMCW) interferometer is presented. The front-end electronics includes a derivative block followed by a the time-variant baseline restoration of the photodetector current. A high signal-to-noise ratio is ensured by avoiding the use of a resistive transimpedance preamplifier and subsequent voltage processing. The paper details the electrical scheme of the preprocessing chain as well as the experimental results from an actual prototype of a distance mete
Analog signal pre-processing for performance enhancement of a distance meter based on frequency-modulated continuous-wave interferometry
No full textA method for the processing of signal from an absolute distance meter based on a frequency-modulated continuous-wave (FMCW) interferometer is presented. FMCW is implemented using a laser diode driven by a current waveform obtained as the superposition of a triangular signal to a bias current kept well above the diode lasing threshold. The analog signal pre-processing includes a derivative block followed by the time-variant baseline restoration of the photodetector current. A high signal-to-noise ratio is ensured by avoiding the use of a resistive transimpedence preamplifier and subsequent voltage processing. The paper details the scheme of the pre-processing chain as well as the experimental results from an actual prototype of a distance meter
Absolute distance meter based on a frequency-modulated laser diode
No full textThis article describes a distance measuring instrument based on a frequency-modulation continuouswave interferometer implemented in a compact setup suitable for industrial applications. Theprototype uses a visible laser diode that is frequency-modulated with a triangular wave form.Measurements carried out with a cooperative target show a measuring range from 130 to 300 mmwith a relative accuracy of 1200 ppm
Dispersive white light combined with a frequency-modulated continuous-wave interferometer for high-resolution absolute measurements of distance
No full textA nonincremental interferometer for the absolute measurement of distances is presented. The measuring technique is based on both dispersive white-light (DWL) interferometry and frequency-modulated continuous-wave (FMCW) interferometry. The proposed configuration integrates both techniques in the same interferometer by use of a single laser diode. This solution enables the results from the coarse measurements from the FMCW interferometer to be combined with the fine readouts from the DWL interferometer. Preliminary experimental results confirm the capability of the system to combine the advantages of the two techniques. (C) 1997 Optical Society of America
Innovative applications of semiconductor laser diodes
No full textNon-contact, non-incremental, and highly accurate distance measurements over both short and extended ranges are required by a number of industrial and medical applications where compact and robust measuring devices suitable for in-field usage are needed. We can find applications in dimensional quality control systems; in both macro and micro profilometry, in wide structure monitoring, in robot tracking, in high precision machining, optical tomography etc..
In this context, we show that new commercial semiconductor laser diodes are suitable for non-incremental absolute distance measurements based on low-coherence and optical frequency modulation.
Even if the knowledge of the coherence properties of these device is of great importance, this information is usually not available in the standard device data sheets. Therefore we present a thorough characterisation of the coherence properties of some commercial visible and near-infrared laser diodes performed using basically a Michelson interferometer.
As example two interferometric systems, based on laser diode sources, are proposed; the main characteristics of these systems are (i) high accuracy combined with an extended measuring range, (ii) simple optical layout, (iii) small dimensions, (iv) low cost
Absolute distance measurement using comb-spectrum interferometry
No full textA measurement technique is proposed based on dispersive interferometry using a comb-spectrum source: dispersive comb-spectrum interferometry (DCSI). The configuration proposed processes the Michelson interferometer output by a dispersive grating in the Littrow configuration. Using a commercial low-cost laser diode source, the non-ambiguity measuring range was measured to be 1.6 mm, whereas the maximum permissible working distance, including ambiguity was measured to be 1.2 cm. The linearity error and stability were measured to be and 32 nm, respectively
Development of an optical sensor for the measurement of surface roughness and waviness
No full textDevelopment of an optical sensor for the measurement of surface roughness and wavines
Dispersive comb-spectrum interferometer: metrological characterization
No full textThe paper reports results of an investigation on the main measurement uncertainty sources in a novel distance meter based on dispersive comb-spectrum interferometry. The light source is a commercial laser diode operating at 670 nm driven under the threshold condition, and emitting a beam with a comb-shaped spectrum. Sensitivity of the measurement to the operating conditions has been evaluated. Results from an experimental activity aimed at characterizing the laser and to measure the performance of a prototype implementation are also presented. The system can perform unambiguous nonincremental distance measurements over a range of 0.8 mm with a total uncertainty of about 1.5 ?
Metrological characterization of a novel absolute distance meter based on dispersive comb-spectrum interferometry
No full textThe paper reports results of an investigation on the main measurement uncertainty sources in a novel distance meter based on dispersive comb-spectrum interferometry. The light source is a commercial laser diode operating at 670 nm driven under the threshold condition, and emitting a beam with a comb-shaped spectrum. Sensitivity of the measurement to the operating conditions has been evaluated. Results from an experimental activity aimed at characterizing the laser and to measure the performance of a prototype implementation are also presented. The system is suitable to perform unambiguous non-incremental distance measurements over a range of 0.8 mm with a total uncertainty of about 1.5 mu m
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