TFT glass thickness measurement

The main activity of our Company is contractual designing, manufacturing, support of electronic devices, development of completely new technologies in the area of laser physics and radio physics. One of the main lines of research in our Laboratory is physical optics, laser interferometry, and fiber optics. Besides fundamental researches in these areas we pay much attention to the development of new optical measuring devices for practical applications.

And we glad to introduce you to one of such a devices on the basis of new interferometry method in white light is a remote optical device for continuous measurement of glass ribbon thickness, that may be used in real production at all stages of glass making.

We suggest for the application in your facilities the instrument allowing for high-precision measurements of glass thickness and detection of its defects. Instruments developed on the basis of this technology are already in operation in many glassmaking facilities making glass, and glass for TFT panels where glass quality shall be monitored with high precision.

Summary technical characteristics of the instrument:

• Measurement of glass thickness up to 1 Angstrom at the processing speed of up to 1 kHz and higher;
• Maximum distance between the head and ribbon may be up to 2.5 meters;
• Thickness measurement range: 0.05-100 mm and more;
• The instrument allows for parallel processing with higher speed at random number of channels. Extension of the number of channels does not require for substantial sophistication of the instrument, thus extension of system's channels does not increase much the cost of the instrument;
• Diagnosis of stuck tin availability for float glass. Measurement method is based on measurement of low tin film absorption by photoacoustic method. Measurement precision can be very high, up to one atomic layer;
• Measurement of glass optical heterogeneity, both float and display glass;
• Measurement of stresses in glass by measuring of birefringence value arising in the glass due to thermoelastic mechanical stresses;
• Glass thickness is measured by interferential measurement principle, and not by triangulation optical method.

Monitoring and measurement data presentation

The device is fully automated and is controlled by a specialized digital processor. Measurement data are processed by this processor and then transmitted to a control room. Besides, these data are recorded on a real time basis into factory's computer network and provide the possibility to follow up in time the line's process mode itself, and to monitor the operation of the measurement device itself. 

Device advantages:

We believe, the above results demonstrate that the new instrument is a very perspective tool for glass ribbon thickness measurement in its several points under real production conditions. In comparison with another known equivalent devices to this one, the new device offers the following advantages:

• The device in the hot area does not contain any precision optical, mechanical and electronic elements. These elements are in the measurement unit located under comfort conditions away from the hot area;
• Optical heads used for illumination of glass ribbon and capture of its reflected light are located outside the hot area. Light into this area gets through protective quartz window, therefore the optical head is practically not heated. As the experience has demonstrated, this may not need special cooling at all;
• The optical head system provides for sufficient operation stability of the device, despite fluctuations in position and inclination of glass ribbon. There is a possibility to further reduce the influence from the inclination to 10 degrees and more;
• There are no big problems for implementation of head scanning across the ribbon;
• The device is able to operate continuously during one day and requires for no adjustment when switching from one thickness to another one;
• The device has low sensitivity to electromagnetic disturbances in the measurement zone.

At our opinion, the device requires for very simple maintenance and its cost will be considerably low than of equivalent devices in case of substantial increase of its functional capabilities.

Could you, please, give consideration to our device for your application at your facilities. We are prepared to submit you more detailed information upon request.