Sources for Terahertz imaging scanner
TeraSense offers two types of generators, both based on IMPATT technology. Our Type I generator has a horn antenna with a specially designed PTFE refractive optical system. The configuration of the PTFE lenses ensures proper focusing of the THz beam onto the linear window of the camera. The Type II generator is an upgraded version of the THz source. It utilizes our most recent breakthroughs in THz technology which enables the enhanced performance of the THz imaging scanner. The Type II module includes our novel reflective THz optics based on our specially configured high-gain horn antenna in combination with a metallic mirror. The Type II sources are made from exceptional IMPATT diodes that deliver significantly more power than the average diode. The Type II generator considerably improves the THz imaging capabilities of our linear scanner by increasing the amount of power reaching the sensor array.
Comparison of THz generators
|Source Type I||Source Type II|
|Frequency||100 GHz||100 GHz|
|Power per pixel||20 µW||140 µW|
|Imaging system dynamic range||24 dB||30 dB|
|Optical system||PTFE optics||Reflection optics|
Below are two THz images obtained as a result of comparative imaging test aimed to show the difference in performance between terahertz imaging scanner equipped with Type I and Type II generators. Four flat figures were cut of metallic foil and placed underneath paper stacks of thickness ranging from 1 to 4 cm. Imaging scanner with Type I source can penetrate only paper stacks 1 and 2 and reveal foil figures hidden underneath the paper. The penetration depth of THz imaging setup with Type II source is much deeper. We can discern fairly clear images of the letters hidden under paper stack 3 and even 4.
Paper stacks of varying thickness with flat metal foil figures underneath
|THz images obtained with Type-I and Type-II generators|