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PDI: Phase Doppler Interferometer
Droplet size and velocity measurements
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Measurements are based on the wavelength of light that is known to high accuracy and does not change due to environmental conditions
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The size of the sample volume can be easily controlled and made as small as the largest droplet to be measured (or even smaller)
![Droplet image](https://static.wixstatic.com/media/ee8bc1_2fd5b12d1dd74ae0b50f418cb2dbc824~mv2.png/v1/fill/w_280,h_205,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/pdi%20droplet%20image.png)
Advantages of the PDI Method for Particle Sizing
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Response is to ballistic or singly-scattered photons; secondary light scattering is not detected
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Signals have a unique sinusoidal character making them easily detectable with high reliability using digital techniques
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Simultaneously measures the size, velocity, and time-of-arrival of every drop
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Forms a direct measurement of the size distribution
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Droplet size range capability of 0.5 μm to 2000 μm or greater
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LWC capability from 0 to 100g/m3 or larger
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Measures in droplet number densities to 100,000/cc, depending on droplet size
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High data rate capability of >100,000 drops/second without loss of readings
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In situ measurements of the sample volume size allowing determination of droplet number density, flux and LWC
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Reliable detection and rejection of ice particles from the droplet size measurement
Key features that are unique to Artium’s PDI include:
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Built-in, high-powered DPSS lasers to enable backscatter measurements through contaminated windows.
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Automated instrument setup features to simplify instrument operation in difficult environments (U.S. Patent 7,564,564, 2009)
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Digital signal detection and full complex Fourier transform signal processing for frequency and phase
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Automatic selection of size range through computer selection of beam intersection angle and beam expansion
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Automatic selection of size range through computer controlled mask selection in the receiver covering at least three size ranges
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Signal intensity validation logic
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Three phase measurements for improved particle measurement reliability and accuracy and rejection of trajectory errors
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Option fourth phase measurement for improved measurement accuracy in dense spray application
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Full complex Fourier transform signal processing with up to 100,000 samples in the signals
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Advanced signal validation logic including tests for variations in frequency and phase over the duration of the Doppler signals (U.S. Patent Pending)
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Computer selectable sample volume size to minimize coincidence errors