Optics: measuring and testing – By particle light scattering – With photocell detection
Patent
1998-08-19
1999-08-31
Pham, Hoa Q.
Optics: measuring and testing
By particle light scattering
With photocell detection
372 22, 2502222, G01N 1506
Patent
active
059460938
ABSTRACT:
A particle detector (10, 12, 70) employs an upconversion laser medium (22, 72) to produce emission radiation (32) at an emission wavelength (56) that is less than the wavelength of the pumping radiation (26). The shorter emission wavelength (56) provides a significant increase in the scattering intensity (I.sub.sc) detected by the particle detector (10, 12, 70), based on the equation I.sub.sc =I.sub.o k/.lambda..sup.4, where I.sub.o represents the intensity of emission radiation (32), .lambda. represents the wavelength (56) of the emission radiation (32), and k represents a coefficient related to particle size. In addition, the emission wavelength (56) of the upconversion laser medium (22, 72) can be frequency doubled to excite biological chromophores such as tryptophan, NADH, and flavin compounds that absorb in the UV spectral range and emit fluorescence at longer wavelengths that can be discretely detected to determine the presence of biological particles.
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DeFreez Richard K.
Kamalov Valey F.
Met One, Inc.
Pham Hoa Q.
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