Ultra-High Sensitivity Aerosol Spectrometer

The UHSAS-G is an optical-scattering, laser-based aerosol particle spectrometer for sizing particles in the 0.06 µm to 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-G ideal for aerosol research and filter testing.


Get accurate sizes for even the smallest particles, and eliminate sizing uncertainty associated with scattering spectrometers that measure at sizes larger than the excitation wavelength.

Categorize particles by size in up to 100 bins (user selects number of bins and boundaries), and count up to 3,000 particles per second.

Rely on the aerosol spectrometry technique with two detection systems: a primary, highly sensitive APD-based system to size smaller particles and a secondary PIN photodiode system to size larger particles.

Compensate for small drifts in laser power via automatic gain control.

Get an on-board computer, built-in monitor, and powerful LabVIEW-designed software for easy, real-time data analysis.

Particle light-scattering

  • A solid-state Nd3+:Y LiF4: ~1054 nm laser illuminates particles.
  • Scattered light is collected by two pairs of Mangin optics – highly sensitive APD-based system to size smaller particles, and a secondary PIN photodiode system for larger particles.
  • Amplification allows detection of particles as small as 60 nm.
Parameter Specification
Auxiliary Parameters


Derived Parameters

Particle diameter

Number Concentration Range

3,000 particles/second

Particle Size Range

60 nm – 1 µm

Aerosol Medium

Air, 0 – 30 °C (32 – 86°F)


Solid-state Nd3+:Y LiF4: ~1054 nm, 1 kW/cm2 intracavity circulating power

Pump Laser: ~797 nm, 1.6 W

Number of Size Bins

100 max:
99 standard bins (98 if both overflow and underflow are enabled)
One overflow bin and one underflow bin

Sample Flow

Standard option: 1 – 100 standard cm3/minute (typically 50)
Other options available

Flow Control

Controlled from software; can also be manually adjusted via mass or volume flow controller

Front Panel Display

Built-in monitor, 2 USB 2.0 ports

Rear Panel Connections

System power switch, system power connection, Ethernet, exhaust vent, exhaust port, serial stream connection

Computer System

On-board Intel®Celeron™ CPU
504 MB RAM
80 GB hard drive for data storage
User interface via standard keyboard, mouse, and built-in monitor (included)


Executable program written in LabVIEW

Data Recording

Output file written to computer hard drive
Output data sent to serial port

Communications Output

Serial, Ethernet, USB

Power Requirements

100-240 VAC, 47-63 Hz, 200W


56 cm L x 43 cm D x 24 cm H

Environmental Operating Conditions

Temperature: 0 – 30°C (32 – 86°F)
RH: 0 – 100% RH non-condensing
Altitude: Sea level to 4 km

Rack mountable unit (standard 19” instrument rack)
External laptop (for remote applications, replaces flat screen display)
Particle-by-particle (PBP) feature (supplies information on individual particles, including inter-particle times)
Bidirectional serial stream communication control

Droplet offers a three-year service plan to ensure that your UHSAS-G continues to deliver high-quality data. This plan locks costs upfront at the time of funding application and covers annual calibration, alignment, cleaning, wear-item replacement, calibration documentation, and shipping. Specific services provided for the UHSAS-G include:

  • Shipping to and from Droplet facility for service
  • Incoming instrument evaluation and health check
  • Full system leak test
  • Filter check
  • Laser power and beam image
  • Power supply and electronics verification
  • Voltages set and verified
  • Optical cleaning
  • Crystal and output coupler alignment
  • Laser alignment
  • Mode match optics alignment
  • O-ring replacement
  • Hardware replacement
  • Jet alignment
  • APD alignment
  • Pulse widths, thresholds, and configuration settings set and verified
  • Flow measurements and coefficients calibration
  • Laser temp set point calibration
  • Current set point calibration
  • YAG reference monitor calibration
  • Pump burn-in
  • Laser burn-in
  • Baseline voltages set and verified
  • Sizing & distribution calibration using Aerosol Generator and PSL’s
  • Ambient distribution
  • Zero count test
  • Data processing
  • 100% unit functionality test
  • Software, firmware, and antivirus update
  • Calibration data, Calibration Report, Certificate of Calibration provided

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