Terahertz Interferometric Detection Using Dual Combs and Electron Multipliers
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Solution Overview
Problem
Conventional terahertz wave measurement methods using lock-in amplifiers and thermal detectors require long integration times and slow response speeds, leading to prolonged measurement times.
Innovation Solution
A terahertz wave interferometric measurement device utilizing an optical pulse train generator, converters, a wave-combining optical system, and a detector with an electron emitter and multiplier to generate and detect terahertz waves at high speed, allowing for rapid detection of terahertz wave interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a lock-in amplifier is used to measure a time waveform of terahertz waves, then measurement accuracy is improved, but measurement time is prolonged
Solution Approach 1:
The patent replaces the conventional lock-in amplifier detection system with a photomultiplier tube-based detection system. The photomultiplier tube directly converts terahertz wave signals into electrical signals through photoelectric conversion, eliminating the need for mechanical scanning and long integration times required by lock-in amplifiers. This substitution of detection mechanism achieves both high measurement accuracy and short measurement time.
Solution Approach 2:
The patent employs dual-comb technology where two optical pulse trains with different repetition frequencies are used to generate terahertz waves. By modulating the optical pulses periodically and combining them, the system creates an interferogram that can be rapidly detected. The periodic modulation allows for fast signal acquisition without requiring long integration times, thus reducing measurement time while maintaining accuracy.
2Measurement precision
If a thermal detector is used to detect interference of terahertz waves, then detection capability is improved, but response speed deteriorates
Solution Approach 1:
The patent substitutes thermal detectors with photomultiplier tubes for terahertz wave detection. The photomultiplier tube uses photoelectric conversion to directly transform terahertz signals into electrical signals, achieving extremely fast response speeds on the order of picoseconds. This replacement eliminates the slow thermal response mechanism while maintaining high detection capability through the photomultiplier's high gain and sensitivity.
Solution Approach 2:
The patent changes the detection parameter from thermal response to photoelectric response. By using optical pulses to generate terahertz waves and detecting them with photomultiplier tubes, the system operates in a regime where the response time is determined by the optical pulse width rather than thermal time constants. This parameter change enables fast response speeds while preserving detection capability.
3Measurement precision
If conventional terahertz wave measurement methods are used, then measurement accuracy is maintained, but productivity deteriorates
Solution Approach 1:
The patent replaces conventional slow measurement systems with a dual-comb photomultiplier-based system. The photomultiplier tube's fast response and the dual-comb modulation technique enable rapid acquisition of interferograms, significantly increasing measurement throughput. This substitution maintains measurement accuracy through precise optical path control while dramatically improving productivity by reducing measurement time from minutes to seconds.
Solution Approach 2:
The patent implements continuous measurement capability through the dual-comb technique. Two optical pulse trains continuously generate terahertz waves that are modulated and detected in real-time. The continuous operation of the photomultiplier tube and the ongoing interference pattern generation allow for uninterrupted data acquisition, maximizing productivity while maintaining accuracy through continuous signal averaging and processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device enables significantly shortened measurement times, enabling effective dual-comb spectroscopy and Fourier spectroscopic analysis of terahertz waves, suitable for applications like spectroscopic and tomographic measurements.
Implementation Method 1
a first converter (21) that converts the first optical pulse train into a first terahertz wave
Implementation Method 2
an electron emitter that receives the third terahertz wave and emits electrons
Implementation Method 3
an electron multiplier that receives the electrons and emits secondary electrons
Implementation Method 4
a wave-combining optical system that combines the first terahertz wave and the second terahertz wave to generate a third terahertz wave
Data Source
AI summary
A terahertz wave interferometric measurement device comprising: an optical pulse train generator outputting a periodic first optical pulse train having a first repetition frequency and a periodic second optical pulse train having a second repetition frequency lower than the first repetition frequency; a first converter converting the first optical pulse train into a first terahertz wave; a second converter converting the second optical pulse train into a second terahertz wave; a wave-combining optical system combining the first terahertz wave and the second terahertz wave to generate a third terahertz wave; a trigger generator generating a trigger signal indicating a timing of detecting the third terahertz wave; and a detector having an electron emitter for receiving the third terahertz wave and emitting electrons and an electron multiplier for receiving the electrons and emitting secondary electrons, and detecting the third terahertz wave at the timing indicated by the trigger signal.