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IDM: Inkjet Droplet Measurement
Droplet size and velocity spray distribution measurements

Inkjet Droplet Measurement System

Proven Capabilities

  • Fast and accurate measurements of droplet streams in real-time

  • Droplet size, velocity, and angle of trajectory measurements for each droplet

  • Very high droplet size and velocity resolution and accuracy (drop size to +/-0.05 μm, velocity to +/-0.05mm/s)

  • Droplet volume down to 0.0005 picolitre (drops size 1 μm)

  • Allows continuous scanning of large numbers of inkjet droplet streams for quality control

  • Highly developed hardware and software for easy integration with inkjet printer systems

  • Very compact and stable optical system design using relatively low power lasers for safety

  • Measurements can be made very near the injector exit and at positions downstream

  • Measures transparent droplets and/or droplets containing solid material with high reliability

  • Allows measurements to ensure perfect location of droplets on the target material

Measurement Method

The IDM instrument is based on the phase Doppler interferometry method. Phase Doppler interferometry uses the wavelength of light as the measurement scale to measure the droplet velocity from the Doppler shift in light frequency and the phase shift of scattered light to measure the droplet size.  Our engineers have developed this method for a wide range of applications including fuel spray combustion, cloud measurements from aircraft, inhalable medical aerosols, and numerous other applications.

Instrument Description

The TK series of IDM instruments consists of a sealed optical head that uses the latest developments in diode pumped solid state lasers (DPSS, miniaturized photodetectors, and electronics). These systems have proven reliability and longevity with expected lifetimes of 20,000 hours. The instruments are factory calibrated and require little or no maintenance or re-calibration. The signal processing electronics are made very compact and reliable by using state-of-the-art large scale integrated circuits and dedicated optical interfaces to the data management system.

The IDM instruments have been demonstrated to be capable of long periods of operation when installed on inkjet printer systems. Continuous scans are performed during system checks at droplet arrival rates as high as 30,000/sec without missing droplets. Proven measurement resolution of better than +/0.05 μm is typical of this instrument’s capability. As described in our patent disclosure (US 7,126,694 B1), simultaneous measurements of drop size and up to three components of velocity are possible to provide droplet size and trajectory for each droplet.

The IDM instruments offer permanent optical alignment for long term use in laboratory and industrial environments. Custom optical designs are available to ensure compatibility with a wide range of inkjet R&D and quality control situations.

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