A miniature laser Doppler probe includes a laser, lens, another lens with a diffraction grating etched thereon, and a focusing lens. The focusing lens focuses the diffraction grating on an interrogation volume which has the particles whose movement is to be detected.
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of the U.S. Provisional Application No. 60/102,151, filed on Sep. 28, 1999.
A compact computer-controlled fully-packaged apparatus providing reliable multi-dimensional characterization of spherical objects in a field environment is disclosed. The apparatus has a rugged, free-space, integrated optical system with up to three lasers that generate at a laser-specific wavelength the coherent light with substantially high pointing stability. The apparatus also has a receiver. Each laser generates a pair of beams crossing each other at a predetermined laser specific angle to form a sample volume such that beams from all lasers coincide in the same spot. The receiver has photodetectors to sense the light scattered from a spherical object. Three photodetectors measure a size and one of the three photodetectors measures a first velocity component, a fourth photodetector measures a second velocity component, and a fifth photodetector measures a third velocity component of the spherical object. The velocity components are orthogonal to each other.
Machine-implemented methods and apparatuses to automatically set-up a signal processing system are described. The signal processing system is set to a first bandwidth. A sampling frequency of the signal processing system is set to a first sampling frequency. Next, first samples of first signals are received at the first bandwidth and the first sampling frequency. First parameters of the first signals based on the first samples are determined. Next, a second sampling frequency is determined based on the first parameters to sample second samples. The first parameters of the first signals may be a mean transit time, a minimum transit time, a mean frequency of the signals, and a standard deviation of the frequency of the signals. Next, a mixer frequency is determined based on the first parameters. A low pass filter is set based on the mixer frequency.
A heat producing device is placed in contact with a heat exchanger that is fluidically coupled to a fluid pump. The fluid pump operates to pumps fluid through a closed fluidic system between the heat exchanger and a spot where the heat can be dissipated. In an aspect, an actuator forces fluid to be pumped without passing through a wall of the pump. One aspect uses an impedance pump as the pumping element.
