FAAM CORE Cloud Imaging Probes (CIP-15 & CIP-100)

CIP

FAAM has 4 Cloud Imaging Probes which are wing mounted single particle optical array probes with grayscale imaging capability and ancillary metrics (TAS, T, Rh, LWC). Manufactured by Droplet Measurement Technologies, the CIPs' fulfil the core requirement for particle sizes over the range of 15μm to 930μm at 15μm resolution (CIP-15) and 100μm to 6200μm at 100μm resolution (CIP-100).

Contents

Instrument specifications

Size range 15 to 930 μm or 100 to 6200 μm
Sample area 40 x 0.93 mm or 70 x 6.20 mm
Number concentration range 0 - 500 cm-3
Number of size bins 62
Sampling Frequency 0.1Hz - 10Hz (1D histogram), PbP 2D image data
Air speed range 0-200 ms-1
Laser Wavelength 658 nm
Temperature -50 to +50 degrees C
Altitude 50,000 ft
Auxiliary parameters Temperature, Pressure, Airspeed

Instrument description

A diode laser produces an oval 50mW beam which passes between the probe arms and illuminates a 200 micron pitch, 64 element diode array

Whenever a particle passes through the beam between the arms, a shadow is generated aacross the diode array.

The diode signal is read and recorded producing an image slice 1 pixel long.

By refreshing the diode array at a multiple of airspeed an image of a particle can be made in multiple slices.

A digital signal processor sizes the particles by slice count and stores the cumulative number of particles of each size in 62 bins.

Data is compressed using run-length encoding and sent to the host computer for real-time display.

Asynchronous image data is transmitted to the host computer whenever the compressed data fills a 4096 byte buffer, the host computer then decompresses a portion of this data for image display, and stores the entire compressed information to disc.

All FAAM CIPs have been upgraded to grayscale imaging providing 3 levels of detail in images. Grayscale levels are nominally set at 30, 50, and 70 % shadowing with sizing being from 50 % shadowing (as per monoscale probes).

All CIPs are fitted with anti-shatter Korolev tips which minimise the effects of particle shattering which can contaminate the sample area. The CIP-15 tips have a short arm-width length of 40mm, and the CIP-100 has a longer arm-width length of 70mm.

Calibration

Post cleaning

The CIP requires no calibration as such being a single particle instrument, though the sizing and imaging performance is checked regularly by use of a spinning disc with known dot size. The spinning disc has calibrated spots of various sizes which pass through the sample beam at 25 ms-1 and should be imaged and sized accurately by the instrument.

Data

CIP data are valid with the standard operating envelope of the aircraft and the raw data are made available to the scientific community via the Centre for Environmental Data Analysis (CEDA). The CIPs' are set to collect data at 1Hz, over 62 size bins. The electronic features include user programmable sample parameters and the software enables real-time monitoring of household variables such as laser operating current, diode voltages and internal temperatures.

Documentation

DMT CIP Grayscale Manual. http://www.dropletmeasurement.com/resources/manuals-guides.

Further details

Contact Dr Chris Reed at FAAM