The World's First Transparent QCM
Now Combine Optical and Mass Measurements in One Device!
Traditional QCM's (quartz crystal microbalances) use a metal electrode on the surface of quartz blank to excite the crystal into to oscillation. While this technique has been adequate for measuring the frequency shift caused my films accumulating on the top of the crystal, it falls short in utilizes all the properties of the sensor. One such shortcoming is the ability to measure the properties of light as it passes through the depositing film, as is routinely done with optical monitoring systems that use a glass chip, light source and detector.
OptoCrystal adds a new dimension to QCM measurement. We replaced the metal electrode with a transparent and conductive layer of Indium Tin Oxide (ITO). With conductivity similar to metals, ITO allows for the passage of light through the crystal sensor while simultaneously coupling it to the oscillator used in QCM control systems. When the crystal is housed in our new Porthole TM see-through crystal sensor head, optical measurements can be made concurrent with mass measurement.
The basic OptoCrystal package for vacuum thin film monitoring consists of:
- A see through, water-cooled, Porthole TM sensor head, constructed of either aluminum or 304 SS (stainless steel).
- A 30" long Teflon coated microcoaxial cable
- A 1" bolt, KF flange, or Conflat flange vacuum feed through with water and electrical (crystal) connections.
- 5 or 6 MHz ITO coated OptoCrystal TM
A variation of the OptoCrystal TM for non-vacuum applications will soon (Spring 2005) available. This unit dispenses with the water lines and can be used in atmospheric conditions. This could be the ideal sensor for examining microbiological organisms or for examining colorimetric changes in thin films while simultaneously measuring changes in film density or mass.
This is suited for use with a Maxtek or SRS liquid QCM controller as well as vacuum deposition monitors.
US Patent Applied For