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Plotting the Journey for HAPS Exploration and Innovation

20th May 2024

If you’ve been following the current trends in aerospace engineering and technology, you’ve likely come across the buzz surrounding High-Altitude Pseudo Satellites (HAPS). Functioning within the stratosphere, these Unmanned Aerial Vehicles (UAVs) serve as indispensable tools for a multitude of tasks. In this blog, we investigate the latest advancements in HAPS developments and highlight the precision optical components integral to their design.

A 3D render of planet Earth at night


Positioned between 18 and 80 km from the Earth’s surface (conditional on model), HAPS are best solar-operated. Consequently, modern models often feature an assortment of photovoltaics (PVs), allowing them to sustain travel for prolonged periods.

These UAVs are also typically outfitted with a selection of top-performing payloads; for illustration, advanced sensors, clear imaging devices, and state-of-the-art navigation mechanisms, to name a few. Highlighting its potential, the market itself is prepared for substantial growth, and projected revenues are predicted to nearly double from USD $85m in 2023 to USD $189m by 2028 [1].

Pioneering space companies such as Airbus and BAE Systems are instrumental in evolving this tech. Airbus’ solar-generated HAPS, named Zephyr, has demonstrated day and night persistence in the stratosphere [2], and similarly, BAE Systems’ PHASA-35 successfully completed a stratospheric flight trial in June last year, surpassing a height of 66,000 feet before landing safely [3].

Cutting-edge HAPS like these are employed to undertake a variety of objectives, comprising:


Due to their vantage point, HAPS are important for extending telecommunications connectivity, particularly in hard-to-reach locations like secluded islands and rural places. By relaying signals between ground-based premises and users, employing cellular, satellite, and wireless comms, the elevated UAVs perform a critical function in connecting communities around the globe.




Japan has taken the lead in improving next-gen infrastructure. The upcoming World Expo 2025, hosted in the Japanese city of Osaka, aims to showcase success by demonstrating communications between remote islands, at sea, and digitally underserved areas by using HAPS. In 2025, the East Asian country is expected to launch UAVs from the platforms, which are reported to supply broader network coverage in comparison to existing ground stations. The news follows Japan’s proposed frequencies – 1.7, 2 and 2.6 GHz – for airborne telecommunication base stations being adopted as the global standard at the recent World Radiocommunication Conference [4].

While laser comms via HAPS may not be viable due to the adoption of radio bands, numerous prospects persist for integrating optics. To illustrate, equipping HAPS with cameras for system maintenance, LiDAR (Light Detection and Ranging) for precise topographic mapping and obstacle avoidance, and infrared (IR) optics for observing heat signatures and surveying ecological conditions.


Over in India, huge progress is underway on a fundamental scheme involving solar-powered HAPS deployed for Intelligence, Surveillance, and Reconnaissance (ISR) intentions, deemed essential for the future of combat. Unlike High-Altitude Long Endurance (HALE) drones, which suffer from limited flight durations, HAPS provide extended functionality and lower operating expenditure. For instance, while a USAF Reaper-class drone costs approximately $3500 per hour to operate, a HAPS-class vehicle is less than $500 per hour, making it an economical solution for overhead observation missions [5].

a surveillance drone flying over a sunsetThanks to their operational longevity and cost-effective nature, HAPS are garnering significant attention from armed forces worldwide for reconnaissance purposes. The capacity of HAPS to deliver persistent observation at a fraction of the price compared to traditional drones makes them an attractive option for military operations.

Of course, this variety incorporates a range of bespoke optical components to ensure accurate and high-quality observation and subsequent communication. Whether integrated with cameras, LiDAR setups, or thermal imaging, optics are poised to fulfil a critical function.

Environmental Monitoring

In addition to military data gathering, HAPS offer promising possibilities for life-saving endeavours. One such application is habitat assessment, which is crucial for successful disaster management. By evaluating environmental and climate-change-induced phenomena such as wildfires, flash floods, earthquakes, hurricanes, and severe storms, these UAVs can contribute significantly to noticing abnormalities and ensuring our safety from harm.


a satellite view of a hurricane


Here, optical technologies like photogrammetry are perhaps among the most obvious choices for integration into HAPS. They can be utilised to monitor changes in land use, analyse natural disasters, and plan conservation efforts. And again, thermography will prove invaluable in assessing thermal patterns in the environment.

Other tools also present opportunities to contribute towards ecological observation, too: 

  • Optical Gas Imaging: To catch emissions of methane and other gases, making them useful for monitoring air quality and identifying hot spots for pollution
  • LiDAR: To create high-resolution 3D maps of features to assess vegetation health, map terrain, and identify potential hazards.

Scientific Research

These techniques are paving the way for a greater comprehension of the planet we live on and its complexities. Whether it’s atmospheric studies or analysing biodiversity and oceanography, they present researchers the opportunity to comprehend the Earth’s environment in unprecedented detail.

Spectroscopy can be advantageous here. For example, HAPS equipped with spectroscopic equipment have the ability to assist scientists in studying different aspects, including atmospheric composition, pollution levels, and potentially even celestial bodies (dependent on the capabilities of the instruments and altitude).

Optical Components for HAPS

High-precision germanium windows by Knight OpticalWith an extensive array of photonics arrangements at their disposal, these innovative platforms have a heightened need for customisable optics designed to enhance comms, imaging, monitoring, and research. As the HAPS market evolves and expands with groundbreaking innovations, these tailored components play an increasingly pivotal role, enabling us to gain a deeper understanding of our universe and advancing infrastructure.

Suitable optical components include: 

  • Germanium Windows: IR-transmitting windows that are frequently utilised in thermal imaging systems and other IR instances due to their high transmission in the mid- and long-wave IR regions.
  • High-precision beamsplitters by Knight OpticalDichroic Filters: Filters that discerningly transmit or reflect light based on its wavelength. Commonly used in fluorescence microscopy, spectroscopy, and colour separation applications.
  • Beamsplitters: Optics that divide a beam of light into two or more separate beams. Found in interferometry, microscopy, and laser-based imaging systems for simultaneous observation or measurement of multiple samples. 
  • Bandpass Filters: Filters to selectively transmit light within a specific range while blocking others that are often used in spectroscopy, fluorescence imaging, and environmental monitoring applications.
  • Polarisers: Optics that manipulate the polarisation state of light for various purposes, including optical communications and glare reduction. Examples include polarisers themselves, retarders (also known as waveplates), and polarising beamsplitters.