European Facility For Airborne Research

European Facility For Airborne Research May 29, 2022, 10:58

Instrument: Manchester 2D-S (stereo) Optical Array Probe

Name Manchester 2D-S (stereo) Optical Array Probe
Acronym SPEC-2DS
Manufacturer Stratton Park Engineering Company Inc.
Manufacturer website
Operated by UNIMAN
Operated onboard

Instrument type

Name Optical Array Probe (OAP)
Acronym Optical Array Probe

Principle of operation

Measured parameter Particle shadow area/diameter
Operating principle

Optical array probe. Cloud particle enters field of view passing through a laser beam. Particle shadow falls on a collecting optical array (normally a photodiode array). This is sampled at a rate such that the pixel resolution in time is the same as that in the across-array dimension. This forms a digitized shadow image of the particle.
From this size and shape are determined, and bulk parameters such as concentration and size spectra derived. Empirical relationships are used to calculate the mass of irregular particles (and hence the ice water content).

Measurement(s) Clouds & Precipitation

Dimension and weight

External dimension PMS/DMT canister mounting instrument
Weight 15.0


Operating mode In situ






Operational restriction

Operational requirements

Certification approvals

Certifed on FAAM BAe146 aircraft

Additional information

This is an updated version of the Optical Array Probe principle. It employs ultra-fast detectors so that 10 micron resolution at sampling speeds up to 200 m/s is possible. By recording the full diffraction image of particles away from the focal plane of the imaging system, estimation of their true size and depth-of-field is possible.

Access, host and processing


Available on the FAAM BAe146 aircraft, operated by University of Manchester

Could also fit on any aircraft having the following characteristics

General description

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