A Design Of A System For Pyroelectric Terahertz Detectors Based On Lithium Tantalate

Terahertz wave refers to the electromagnetic radiation whose frequency is between 0.1THz and 10 THz. It locates between microwave and infrared. Because of its particular frequency, terahertz wave has many special properties such as transmittance, coherence, transient, low-energy and so on. Terahertz wave is widely used in many fields like biomedicine, communications, public safety, nondestructive testing and military. Due to the development of new technologies and new materials, terahertz technology is getting more and more popular and a terahertz research boom has been brought out around the world. Although great progress has been made in studying and understanding of terahertz radiation, the terahertz is still very hard to be detected.Under the above background, the 32-channel terahertz pyroelectric detector has been taken as the main study object. The analog to digital conversion and high speed transmission of the terahertz signals have been achieved by using the FPGA(Field-Programmable Gate Array) as the logic control unit and through the ADC chip AD7490 and Ethernet transmission chip DM9000 A underlying program development and design. Finally the software platform of the terahertz detection system corresponding with the hardware has been successfully developed through the use of MFC library. The details are as follows:Firstly, the working principle of pyroelectric terahertz detectors were introduced and then a preparation method of pyroelectric terahertz detectors with 32 channels based on lithium tantalate films by using the ways of mechanical polishing and semiconductor processing has been put forward.Secondly, a terahertz detection hardware system including a preamplifier module, an analog to digital conversion module, a data transmission module and a control module based on FPGA was built, and then the underlying driver of the chips and the control logic of the system were completed by finishing the design of FPGA. In terms of data transmission, the ethernet transport solution with high transmission speed, compatibility, and low cost was chosen as the data transmission mode of detection system by comparing with serial transmission and PCI-E transmission.Finally, a software platform of the THz detection system was built by using the Microsoft Foundation Class Library, which has realized the reception of terahertz data, finished the real-time display and completed the drawing of the histogram and V-T images by using double-buffered graphics technology. What is more, the operating skills and specific functions of this software were also been introduced.It was verified that the pyroelectric terahertz detection system with good stability, low cost, portability and other characteristics was able to meet the requirements for terahertz detection.