Reinforcing the safety and security of the passenger journey

http://www.airport-business.com/2020/04/reinforcing-safety-security-passenger-journey/

The global COVID-19 pandemic continues to spread at an alarming rate, causing great harm to the world economy and global aviation industry. Serving at the forefront of people flow, both airlines and airports serve as the gatekeeper to fight against the possible spread of the virus. To ensure safe travel for the general public, they are striving to help identify and take care of infected travellers, protecting and facilitating the healthy flow of passengers.

Prof. Zhiqiang Chen from Tsinghua University, Chairman, President and Chief Executive Officer, NUCTECH: “As the pandemic is ravaging the world, COVID-19 may change our perception of security once and for all. It is envisaged that airports might be tasked to guide against not only the explosives, but also the equally devastating health risk.”

“As the pandemic is ravaging the world, COVID-19 may change our perception of security once and for all,” says Prof. Zhiqiang Chen from Tsinghua University, Chairman, President and Chief Executive Officer, NUCTECH. “It is envisaged that airports might be tasked to guide against not only the explosives, but also the equally devastating health risk.”

Some experts believe that we are likely to live with the health testing, such as temperature checks, well after the pandemic is over, just as the liquids ban still exists post the foiled liquid explosive attack in 2006.

Protect by detection

The World Health Organization claims that exported cases of coronavirus were “detected through entry screening” and added that the spread of the disease could be reduced if temperature screening was used. Indeed, airports in Thailand, China and Mexico are starting to use thermal scanners on incoming passengers. Against this backdrop, NUCTECH has integrated its proprietary thermal imaging camera into its Terahertz body scanner to launch a one-stop solution for real-time people screening, helping airports, airlines and other aviation authorities to safeguard the travellers and protect their staff.

“By using the integrated solution, our Terahertz body scanner can precisely alert passengers with elevated body temperatures within 2.5 metres, assuring a smooth and non-intrusive screening for suspect patients,” Prof. Chen explains. “With no close contact needed during the process, it serves well to protect the staff by allowing them to be situated away from the passenger flow, observing social distancing while on duty. If people with abnormal temperatures are found, an alarm would be automatically triggered, and the operators are immediately notified to take on further actions, whether it be some additional check-ups of temperatures, or further inquiries of their travel or contact history.”

Located in the passage or entrance of the terminal, the integrated solution allows for an extra layer of security and safety at the airport. Finding the suspect patients early on, before they reach out to the bigger crowd at the checkpoint, can significantly decrease the risks of virus transmission.

Equipped with deep learning algorithms, the integrated solution can adapt quickly to different settings, minimise background distractions, and detect faces accurately. It also detects the body temperature of people standing still or moving around with high precision.

“The integrated solution boasts a throughput of over 2,000 persons per hour to accommodate a high footfall scenario by allowing multiple people to be screened simultaneously,” says Prof. Chen. “It eliminates the need for line-ups at temperature checkpoints, curbing the spread of any possible virus through congregation.”

To accommodate myriad scenarios, the thermal imaging module can also be integrated with a variety of NUCTECH scanners to implement a more thorough security and safety check for the travellers. “Combined with our metal detector portals, passengers can be checked for elevated body temperatures alongside any concealment of sharps or weapons, allowing for a safe, smooth and reliable screening experience,” Prof. Chen comments.

NUCTECH has integrated its proprietary thermal imaging camera into its Terahertz body scanner to launch a one-stop solution for real-time people screening, helping airports, airlines and other aviation authorities to safeguard the travellers and protect their staff.

Respond by isolation

When passengers with high temperature are detected through the integrated solution, the airport needs temporary quarantine room for those suspect patients before medical care arrives. During the waiting period, the airport is obligated to protect its staff and the general public from contracting the virus, so a quarantine area is required to isolate the patients for further medical treatment.

To help airports prepare for this situation, NUCTECH has developed a proprietary convertible quarantine room to separate suspect patients from the general public and cut off the transmission of any virus. “The walls of the chamber are made of a unique composite material to allow for a sterile environment,” says Prof. Chen. “Further equipped with an Ultra Violet module, it can be activated to disinfect the chamber thoroughly after the patient has been transferred. With the self-sterilization module in place, the quarantine room can be reused safely.”

NUCTECH has developed a proprietary convertible quarantine room to separate suspect patients from the general public and cut off the transmission of any virus.

Combined with data processing technology, the quarantine room also enables non-contact investigation of the passenger’s identity, travel history or possible connection with confirmed cases, etc. “With the two-way intercom system integrated, the quarantine room can better support airport staff to do their job without risking their own lives to be exposed to dangers,” Prof. Chen explains. “By adopting a modular design, the compact quarantine room is easy to set up or relocate to other hotspots around the airport, addressing ever-changing needs from different locations. Experienced staff can complete the installation within half an hour. Just basic training would be sufficient to make it work.”

Non-contact journey

The impact of COVID-19 on aviation is potentially huge and longstanding. Even after the crisis, we might see the travel experience quite different from what existed before. “Security might be redefined as something more than a freedom from dangerous items, but a more comprehensive notion encompassing physical and pathological dimensions,” says Prof. Chen. “To cope with this new trend, airports and industry need to collaborate hand-in-hand to get our aviation sector fully prepared for the post-COVID-19 era.”

In addition to the widespread temperature checks, the future travel experience might also include contact-free processing to avoid transmission of any virus or bacteria in the airport. Prof. Chen explains that more high-tech solutions could be introduced to the passenger journey, including automatic self-check-in, self-bag drop or paperless identity authentication. “As for the security checkpoint, promising technologies would also be more widely adopted to minimise unnecessary physical contact, without compromising security.” These may include:

• “Checkpoint CT scanners, allowing passengers to keep liquids and laptops in their bags. Much fewer trays would be required, reducing the possibility of infection via physical touch.”
• “Automated tray return systems free staff from the troublesome and now dangerous tray moving.”
• “Checkpoint CT scanners and next-generation body scanners, reducing the need for pat downs or physical searches, and minimising close contact between passengers and officials.”
• “Remote screening, allowing for social distancing by enabling the screener to be situated in a separate location away from the hustle and bustle of the checkpoint, as well as the possible transmission of any dangerous viruses. It can effectively protect its workforce from the health risk while at the same time ensuring the efficiency of the security check.”

“By using the integrated solution, our Terahertz body scanner can precisely alert passengers with elevated body temperatures within 2.5 metres, assuring a smooth and non-intrusive screening for suspect patients,” says Prof. Zhiqiang Chen from Tsinghua University, Chairman, President and Chief Executive Officer, NUCTECH.

High power laser sources at exotic wavelengths

Members of the team in the lab at Tsinghua (from left) Xiaojian Wang, Doudou Gou, Lei Zhang and Sigang Yang

High power laser sources at exotic wavelengths may be a step closer as researchers in China report a fibre optic parametric oscillator with record breaking efficiency. The research team believe this could lead to new light sources for a range of biomedical imaging applications.

: http://phys.org/news/2014-04-high-power-laser-sources-exotic.html#jCp

Discrete ranges

Mature commercial laser platforms are available for common output wavelengths. Some applications, however, require wavelengths that cannot readily be produced with established technologies. Several of these are in the field of biomedical imaging and spectroscopy (e.g. coherent anti-Stokes Raman scattering microscopy and optical coherence tomography). In such systems if the wavelength of light used can be optimised for the biological environment the performance can be greatly improved.

For fibre lasers the most commonly available outputs are around 1.06, 1.5 or 2.0 µm. Developing materials that can provide gain in less conventional wavelength bands is difficult and it is easier to employ conversion from the wavelength of a more conventional laser source.

Fibre optical parametric amplifiers (FOPAs) can convert optical energy from conventional wavelengths and a fibre optical parametric oscillator (FOPO) based on the gain from a FOPA can generate tuneable radiation. Theoretically, FOPAs could provide optical gain at nearly any wavelength and so FOPOs could emit laser beams in nearly any wavelength. However, low conversion efficiencies limit the usefulness of FOPOs as light sources.

SEM image of a cross section of the phonic crystal fibre created for the fibre optical parametric oscillator

Designed gains

In the work reported in this issue of Electronics Letters, a team from Tsinghua University in Beijing present a photonic crystal fibre (PCF) FOPO with high conversion efficiency, to show the feasibility of FOPOs as practical light sources.

"Energy conversion efficiency up to 36% is achieved." said team member Dr Lei Zhang. "That means a high output power can be obtained at the new wavelengths. Potentially, lasers with high power can be obtained in a wide wavelength regime. This is the first time that a high efficiency FOPO is achieved by using a PCF as the gain medium."

The Tsinghua team attribute the high efficiency of their design to three factors. Firstly, large parametric gain provided by an optimized PCF, achieved through careful design of the dispersion and nonlinear properties of the fibre. The PCFs, fabricated and tested by FiberHome Telecommunication Technologies, were shown to be able to provide large gain in a very wide wavelength range. The second factor is walk-off effect, which has a critical influence on the optical gain. To minimize walk-off, they use a 'homemade' picosecond mode-locked fibre laser as the pump, instead of a femtosecond unit, giving a wider pulsewidth. The interaction length between the signal and the pump in the gain fibre is longer, so more of the pump energy can be converted to the signal wavelength.

The third key factor cited by the team is a concentration on minimising losses in the laser cavity by using an all fibre FOPO configuration, given a dramatic improvement in efficiency compared to their previously reported results. In their previous configuration a free-space optical time delay line was placed in the oscillator cavity to tune the cavity length, incurring a 4 dB loss. To avoid this, in the current work a specific length of optical fibre is used to adjust the cavity length.

Filling in the gaps

The team expect the first applications of their work will be in bio-medical imaging, as the radiation their design can produce is well matched with the requirements of emerging technologies in this area. However, to achieve high efficiency output across a wide wavelength range the cavity length needs to be tuneable. "In the FOPO configuration, the signal pulse needs to be synchronized with the pump pulse. So an optical cavity with adjustable length is preferred. In our experiment, the cavity length cannot be tuned, so at some wavelengths the signal cannot be tuned to synchronize with the pump. It is not a continuously tuned source. So it is important to develop an optical delay line with low loss at a wide wavelength regime." Said Zhang.

The team are now working to improve conversion efficiency in the signal and idler simultaneously by making a double-rings cavity FOPO that allows the signal and idler to oscillate simultaneously. They are also working to extend the output wavelength range. "Our research interests also focus on terahertz generation based on difference frequency generation from FOPO and terahertz parametric oscillators." said Zhang. "We think in the next decade, the operating wavelength of FOPOs can be extended to, for example, generate mid-infrared light and even terahertz. And the conversion efficiency will be higher. Eventually I think it will be possible to tune a FOPO in a wavelength region over 1000 nanometers."

Polymer pipes support singlemode terahertz transmission

By Gail Overton
Senior Editor

http://www.laserfocusworld.com/articles/print/volume-49/issue-11/newsbreaks/polymer-pipes-support-singlemode-terahertz-transmission.html

Tsinghua University and Capital Normal University (both in Beijing, China) researchers have demonstrated that large-diameter polymer light pipes can transmit singlemode terahertz radiation when fabricated with the proper physical parameters.

Fabrication begins with a single polymethylmethacrylate (PMMA) hollow tube that is filled with seven small PMMA hollow tubes and drawn into polymer light pipes with two layers. The outer pipes are 3–4 mm in diameter with 200 μm wall thickness, which support the hexagonal inner pipe by six thin walls. Experimental and theoretical modeling of the configuration as a function of the radius of the inner pipe (r) show that singlemode guiding of a terahertz wave is accomplished when the radius value is near 1 mm. This is because in this condition, only the HE11 mode field concentrates in the inner pipe, whereas the fields of all the higher modes expand to the space between the inner and outer pipes leading to high attenuations in these modes. For a 15-cm-long sample of the polymer pipe transmitting a 3.1 THz light beam, the insertion loss was measured at 5.34 dB including the coupling loss at the input end. Contact Wei Zhang at zwei@tsinghua.edu.cn.