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Ultra High Sensitivity Aerosol Spectrometer (UHSAS)


Operated By: 

The UHSAS (top right) and 2DC (bottom left) mounted under the wing of the

The UHSAS is an optical-scattering, laser-based aerosol particle spectrometer for sizing particles in the 0.06 – 1 μm range. The instrument counts particles in up to 100 user-specified sizing bins, with a resolution as fine as 1 nm/bin. This high sensitivity makes the UHSAS ideal for aerosol research and filter testing.

A laser illuminates particles, which scatter light that is then collected by two pairs of Mangin optics. One pair of optics images onto a highly sensitive avalanche photodiode (APD) for detecting the smallest particles. The other pair images onto a low-gain PIN photodiode for detecting particles in the larger size range of the instrument. Each detector is amplified in a current-to-voltage stage that feeds into the analog electronics system. The amplification allows the system to detect particles as small as 60 nm.

Instrument Type: 
Global Hawk - AFRC, Gulfstream V - NSF
Point(s) of Contact: 
Darrel Baumgardner (Prev PI), David Rogers (POC; PI)