1,721,131 research outputs found
Optical flow sensor through near-field grating diffraction
No full textA novel optical flow-meter has been developed, especially designed for very-high flow speed. The system is a variant of laser Doppler velocimeter (LDV), realized by means of an optical phase-grating. Standard LDV generates a fringes pattern by means of two laser beams, intersecting at an angle. For fast flow
rates, the fringe period has to be very long, in order to avoid too high output frequencies, therefore a very low angle is required. For the realization of such pattern we propose a different approach, employing an optical grating, working in the near-field range. This technique has been demonstrated by measuring the flow-speed distribution in a water-jet machine
Dual Wavelength Moisture Meter for Clay
No full textAn optical sensor for measuring the moisture level of clay has been realized by a couple of telecommunications lasers at 1300 and 1550 nm. The sensor can operate directly during building material production. The measurement principle is based on the measurement of the optical reflection at different wavelengths in the infrared region. Custom low-noise electronics allows rejecting disturbances of ambient light, and a digital processing makes the system independent on the clay distance. By means of a proper calibration, the sensor can monitor the moisture level during brick production, without moving parts or optical filters
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