| US 7,586,603 B2 | ||
| Method and apparatus for improved signal to noise ratio in Raman signal detection for MEMS based spectrometers | ||
| Sandip Maity, Bangalore Karnataka (India); Ayan Banerjee, Bangalore (India); Anis Zribi, Rexford, N.Y. (US); Stacey Kennerly, Niskayuna, N.Y. (US); Long Que, Rexford, N.Y. (US); Glenn Claydon, Wynantskill, N.Y. (US); Shankar Chandrasekaran, Tamil Nadu (India); and Shivappa Goravar, Laxmeshwar Karnataka (India) | ||
| Assigned to General Electric Company, Niskayuna, N.Y. (US) | ||
| Filed on Apr. 17, 2008, as Appl. No. 12/104,471. | ||
| Application 12/104471 is a division of application No. 11/459449, filed on Jul. 24, 2006. | ||
| Prior Publication US 2008/0204743 A1, Aug. 28, 2008 | ||
| Int. Cl. G01J 3/44 (2006.01) | ||
| U.S. Cl. 356—301 | 14 Claims |
| 1. A method of Raman detection for a portable, integrated spectrometer instrument, the method comprising:
directing Raman scattered photons by a sample to an avalanche photodiode (APD), said APD configured to generate an output
signal responsive to the intensity of said Raman scattered photons incident thereon;
amplifying said output signal of said APD and passing said amplified output signal through a discriminator so as to reject
at least one or more of amplifier noise and dark noise;
counting a number of discrete output pulses within a set operational range of said discriminator so as to determine a number
of photons detected by said APD; and
passing said output signal of said APD through a preamplifier so as to shape an output current pulse from said APD to a NIM
standard pulse.
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