Terahertz time-domain spectroscopy system for realizing terahertz quick imaging by using frequency optical comb

Abstract

The invention discloses a terahertz time-domain spectroscopy system for realizing terahertz quick imaging by using a frequency optical comb. The system combines different structural units into the same region according to a transmittance characteristic of a periodic structure to obtain a transmittance spectrum with stacked transmittance peaks; the stacked transmittance spectrum forms a frequency optical comb in a frequency spectrum; a transmittance characteristic of an imaging optical comb is related to a space arrangement position of the periodic structure; based on the relevance, a large-light-spot terahertz light beam can enter the imaging light comb and an object to be measured; and a transmittance signal is collected by spot detection. Transmittance characteristic space distribution information of the object to be measured is extracted through data processing, so that quick imaging can be realized. The terahertz time-domain spectroscopy system is suitable for wide-band terahertz imaging; compared with the conventional point-to-point scanning imaging system, the terahertz time-domain spectroscopy system has the advantages that the imaging time is greatly saved; a new concept is supplied to terahertz imaging detection; and the terahertz time-domain spectroscopy system has a great significance for large-scale application of terahertz safety detection and identification.

Description

technical field [0001] The invention relates to the field of terahertz applications, in particular to a terahertz time-domain spectroscopy system for realizing terahertz fast imaging by using a frequency optical comb, and also relates to the design, processing and imaging method of the terahertz imaging optical comb. Background technique [0002] As THz science and technology are getting more and more attention, it has entered the stage of practical application in communication, radar, detection and imaging. The transmission-reflection properties of metal periodic structures show great potential in the realization of THz devices, such as filters, switches, polarizers, phase retarders, etc. The advantages of studying the transmission properties of metal periodic structures in the THz band are: 1) Most metals almost behave as perfect conductors in the THz band, and the difference in conductivity of different metals will not affect the transmission properties of metal periodic ...

AI Technical Summary

Problems solved by technology

At present, terahertz time-domain spectroscopy system imaging generally adopts a point-by-point scanning imaging method, using a focused terahertz spot to perform two-dimensional scanning on the sample surface. According to the size of the sample and the size of the terahertz spot, this method takes a very long time to operate.

And this scanning requires the use of a focused terahertz spot, and the imaging system requires four parabolic mirrors

When measuring, the sample is placed vertically on the focal point of the parabolic mirror, otherwise it will have a relatively large impact on the experimental results, and the two-dimensional translation stage is used to control the sample position, the experimental system is complicated, the technical difficulty is high and the test cost is relatively high, which limits its large scale. scale application

In addition, the use of detector arrays can achieve fast imaging, but the size of the terahertz detector unit limits the size of each imaging unit, the imaging resolution is limited, and the terahertz detector itself is expensive, and the cost of the detector array is too high, which is not suitable for Large-scale practical application

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