Promising Test Results for Ceramic Tiles Industry
TeraSense, as a leading manufacturer of affordable and compact equipment for terahertz imaging, constantly improves its original patent-protected technology and continues series of tests of newly developed product for various industrial applications.
This time we tried a new "Type II" terahertz source, which features enhanced output power characteristics as a part of our High Speed Linear Scanning System for test of ceramic tile samples. The 4-x increase of THz power per pixel of the new Type II source extends our Terahertz High Speed system's capabilities in terms of penetration depth of various visually opaque materials including ceramic tiles.
The samples used for the tests were 'green' and 'finished' ceramic tiles in order to define various defects along different stages of production process, i.e. uneven moisture, cracks and thickness differentiation.
Samples:
“Green” ceramic tiles, 6.5 mm thick, of following quantities:
1) 0.3% moisture – 6 pcs.
2) 5% moisture – 6 pcs.
Measurement equipment:
1) TeraFAST high-speed linear sub-THz camera, integrated into conveyor system.
2) Tera-1024 sub-THz camera.
3) Type I sub-THz source (100 GHz output frequency).
4) Type II sub-THz source (100 GHz output frequency).
Test results:
All samples and stacks of up to six similar samples were tested for sub-THz signal attenuation @ 100 GHz frequency. Test results are summarized in Fig. 1.
From the results obtained we get the following values for signal attenuation (dB/mm) per unit length:
Fig.1: Signal attenuation vs. moisture.
Conclusion and recommendations:
Dry (0.3% moisture) tiles show medium signal attenuation @100 GHz and are suitable for measurements at existing conveyor-based imaging system: TeraFAST + Type I sub-THz source. Wet (5% moisture) tiles have strong signal absorption @100 GHz, and only thin (6-8 mm) tiles could be measured at TeraFAST + Type I sub-THz source imaging system.
For 5% moisture tiles we offer the new Type II / Type III sub-THz sources, providing higher power density of probing sub-THz signal.
Type II sub-THz source (now available for order) and Type III sub-THz source (forthcoming model, now available for pre-order). Optimal tile thickness range for different moisture and measurement system types are given in table below:
