IDM: Inkjet Droplet Measurement
Droplet size and velocity spray distribution measurements
Artium has been providing instruments for the development of inkjet printer technology for over two decades beginning with delivery of instruments to IBM and Hewlett Packard. The phase Doppler technology which is the basis of these instruments was invented by our senior scientist and first developed by our previous company, Aerometrics, Inc. Artium has continued the development with funding from NASA and the U.S. Army The method has proven to be ideal for inkjet printer development. Our Inkjet Droplet Measurement (IDM) instruments measures droplet size, velocity, and angle of trajectory simultaneously in real-time. Measurements are easily performed in situ and nonintrusive without interfering with the droplet stream. The TK line of IDM instruments are very easy to use and have a very long lifetime.
Over the past decades, the instrument has been thoroughly evaluated for inkjet spray applications and with proven high resolution, accuracy and reliability. Currently, we are supplying instruments for development and quality control applications to a major supplier of OLED display fabrication systems. The instruments measure at rates of 10,000 droplets per second (or greater) while continuously scanning large arrays of inkjet droplet streams.
Why Analyze Droplets In-Situ?
Nozzle consistency: Some inkjet heads feature individually addressable nozzles. In-situ drop analysis can be used to optimize individual nozzle voltages for highly consistent performance across the head.
Wetting problem identification: High magnification cameras identify wetting problems in early stages of development.
Drop characteristic verification: For many application, a particular drop volume of velocity is required. Jetting parameters and ink formulations may be adjusted until in-situ analysis determines that the desired characteristics have been achieved.
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
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.
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.