Terahertz Spectrometer

Content
1. What is terahertz spectrometer?
    1.1 What is terahertz?
    1.2 Working principle of terahertz spectrometer
2. Terahertz spectrometer application
3. How to purchase terahertz spectrometer?

Terahertz spectrometer (THz spectrometer) is a physical property testing instrument used in the field of physics, surveying, and mapping science and technology.

There is a vacuum in the electromagnetic spectrum that has not been effectively understood and utilized by human beings, with a frequency range of 100 GHz-10 THz (Terahertz, 1×10e12 Hz), located between microwave and infrared radiation, which is the "terahertz gap". For a long time, while microwave, visible light, and infrared technologies have been widely used, terahertz has lagged relatively behind in scientific research and applications, and the reason is the lack of effective terahertz detectors and emission sources. In recent years, with the improvement of scientific research tools, research in this field has developed significantly. This particular waveband is considered to be the frontier of the century's technological revolution.

Due to the special location of terahertz waves in the electromagnetic spectrum, they have many unique advantages compared to other bands of radiation.

a. Compared with microwaves and millimeter waves, terahertz has a very high frequency, so its spatial resolution is also very high.

b. Terahertz pulses are short, so they have a higher temporal resolution.

c. Compared with infrared radiation, terahertz waves can pass through sand, dust, and smoke more easily, are less affected by harsh weather conditions, and have a wider field-of-view search range.

d. Compared to X-rays, terahertz energy is small and does not have a destructive effect on matter.

e. Terahertz waves can penetrate most non-polar materials, and the resonant frequencies of vibrations and rotation frequencies of biological macromolecules are in the terahertz band, making them suitable for the biopsy of biological tissues.

f. The above-mentioned properties of terahertz have broad application prospects in the fields of spectral imaging, nondestructive testing, security inspection, biomedicine, classified radar, radio astronomy, broadband communication, etc.

Terahertz is a "top-down" region in the electromagnetic spectrum. In a broad sense, the terahertz frequency range is from 0.1 THz to 10 THz and sometimes refers specifically to electromagnetic waves in the frequency range of 0.3 THz to 3 THz.

The wavelength on the left side of the terahertz wave in the long-wave direction belongs to the microwave category, and microwave technology is quite mature as far as it is concerned. The short-wave direction on the right side of the terahertz wave belongs to the infrared range, and the higher frequency belongs to the visible range, using optical theory can explain the optical phenomena very well. Terahertz wave is located in the far infrared and microwave between the "awkward" section of electromagnetic waves. It combines the intersection of several disciplines such as optoelectronics, semiconductors, and materials science, and is a field that is currently under intense research and development. Until the 1980s, the development of this band was greatly limited by the lack of stable terahertz radiation sources and sensitive terahertz detectors in the hardware, known as the terahertz gap.

In recent decades, with the intensive research in the field of photonics and electronics, advances in ultrafast laser technology, nonlinear optics, and microelectronics have led to the rapid development of terahertz wave radiation and detection technology. The development of terahertz technology has led to the application of terahertz waves in various fields and has become a research hotspot in the world today.

Due to their special position in the electromagnetic spectrum, terahertz waves also have the dual characteristics of both macroscopic classical theory and microscopic quantum theory. The unique properties of terahertz waves are as follows.

The quantum energy of terahertz waves is very low (the quantum energy of terahertz waves with a frequency of 1 THz is only 4.1 meV) and does not cause harmful ionization reactions.

Good penetration of most dielectric materials and non-polar liquids. For example, terahertz waves can penetrate objects of opaque materials such as paper, knitted fabrics, plastics, ceramics, and wood to detect their internal structures.

The frequency band of terahertz pulses can cover the range of 0.1-10 THz, and many substances have rich spectral information in the terahertz band, and the composition of substances can be judged based on the rich absorption characteristics of these substances in the terahertz band.

When a terahertz light source is scanned against a sample object, all materials will absorb specific wavelengths and the rest will reflect or transmit, just as the human eye sees various colors. When a terahertz pulse irradiates a sample, different materials absorb and reflect terahertz waves differently, so it is possible to distinguish isomeric materials that cannot be identified with the naked eye based on different absorption or reflection profiles. Each material has a different absorption and reflection rate for different wavelengths of light, resulting in a specific spectral pattern, which is called a material-specific fingerprint spectrum.

Currently, two excitation sources can excite terahertz waves and complete the spectral detection: microwave terahertz and laser terahertz.

a. Higher power output in single or narrow-band cases due to the electronic device that generates the microwave.

b. The high signal-to-noise ratio of the terahertz source allows for a clearer view of the results when the sample is detected, without interference from the bottom noise.

c. In the case of some single wavelength or narrow-band wave absorption rate of more than 80% or even 90%, the signal feedback can be obtained by increasing the output power and observing the response results.

a. As the microwave can output a narrower spectral width, the observable range for the object is relatively small. Only a single material can be identified to respond.

b. If the tested sample does not reflect specifically on the band, then when the body is examined in the narrow band detection wave range of absorption reflectivity differences tend to zero while other bands will have large differences, and the terahertz detection graph by microwave excitation will appear to be identical wave pattern, which cannot be found by the results of the differences in the graph.

The laser-excited terahertz light source can output a relatively wide spectral range, enabling more accurate identification of the fingerprint spectrum of the scanned body in a wider range with higher resolution, accuracy, and general applicability. It can identify fingerprint spectra of many different materials and can be compared horizontally.

Due to the need to take into account the simultaneous output of multiple wavelengths, the laser terahertz excitation source is not able to achieve the maximum level of microwave output power. This results in the detection process, the laser terahertz wave in the case of a material for a particular wavelength absorption rate is high, the returned optical signal may be drowned in the bottom noise difficult to be identified.

Terahertz wave is one of the most successful applications of using fluoroscopic imaging technology to make various security monitoring devices. It can be used for security inspections at airports, stations, and other places. The high resolution of terahertz waves can identify dangerous goods not only in form. And it can also identify the type of dangerous goods, especially since it is of great use in detecting and identifying plastic murder weapons, ceramic pistols, plastic bombs, fluid explosives and suicide bombs, and drugs.

The principle of fluoroscopy-based imaging technology is simply that the terahertz emission source is placed on one side of the object being detected, and the receiver and imaging device are placed on the opposite side of it. If the object absorbs fewer terahertz waves, such as plastic, the wave can pass through the problem, and the wave transmission is relatively large; if the object absorbs more terahertz waves, such as water, the terahertz wave at this time attenuates inside the object and passes through, and the transmission is relatively small. According to the amount of transmission, not only the shape of the object can be determined, but also the type of material. The display content is determined according to the purpose of detection.

If terahertz quality inspection equipment is installed on the production line, the quality of the product can be greatly ensured. In the case of pharmaceutical production lines, it is possible to detect in time those products with excessive moisture content. In the production line of fiber materials for timely detection of quality defects. In the production line of plastic products, timely detection of defects such as bubbles and delamination. Detecting product quality on the production line of composite ceramics and ceramic bearings. This terahertz fluoroscopic inspection is a non-destructive inspection technique and is easy and timely.

There are various methods used for non-destructive testing, such as X-ray, infrared, light wave, microwave, terahertz wave, and ultrasonic. The choice of which wave to inspect depends on the purpose of the inspection and the performance of the wave.

If you are interested in our terahertz spectrometer or have any questions, please write an e-mail to [email protected], we will reply to you as soon as possible.