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TIRI x NLPI Special Exhibition: Unboxing Taiwan's One and Only Large Aspheric Mirror

The National Science and Technology Council (NSTC) hopes to help young students build knowledge in science and technology through activity early so they can have the ability to one day shape the future. In light of this policy, the Taiwan Instrument Research Institute (TIRI) of NARLabs has cooperated with the National Library of Public Information (NLPI) to launch the special exhibition 'Fact, Not Fiction: Unboxing Taiwan's Only Large Aspheric Mirror.' The exhibition is on display at NLPI's Digital Art Center (2F) from Nov. 14, 2023, to March 17, 2024. The exhibition aims to help young students and their parents understand Taiwan's longstanding achievements in precision optical technology and introduce basic scientific knowledge from the field.

Optics is a basic science that permeates our everyday lives. For example, cameras, microscopes, LED lights, lasers, spectrometers, and telescopes are just a few of the optical technologies or instruments that we can frequently see. In the production of optical systems used for astronomical observation and remote sensing satellites, large aspheric mirror technology is a major bottleneck. This is because the necessary components, most of which are internationally regulated exports, cannot be purchased for any amount of money, meaning that the technology must be developed independently. This exhibition highlights the large aspheric mirror for satellite remote sensing systems developed by TIRI's technology team.

The main reason why satellite remote sensing systems use aspheric mirrors is that when light passes through a spherical lens, the light from the center and the edges of the lens cannot converge at the same focal point, resulting in "spherical aberration," which makes the edges of an object look slightly blurry. An aspheric lens, on the other hand, eliminates spherical aberration through change in the radius of curvature. This way, light from the center and the edges of the lens converge at the same focal point, impROVing the quality of the image. In comparison, aspheric lenses are more efficient than spherical lenses in correcting aberration and impROVing optical quality, and a fewer number of them are required in an optical system.

Since the curvature of the aspheric lens is continuously changing, it is not possible during manufacturing to polish its large area with fixed curvature grinding tools as with traditional spherical lenses. Therefore, it is necessary to rely on the experience of optics technicians as well as advanced computer numerical control (CNC) technology to gradually polish and correct the lens, greatly increasing the difficulty of research and development. Production time for the lens is very long, and testing is stringent and requires special technical assistance. Overall, the process of designing, manufacturing, and testing large aspheric lenses is very complicated. TIRI, however, worked through the polishing and testing technologies step by step and was able to complete its own large aspheric lens for satellite remote sensing systems.

The "Fact, Not Fiction: Unboxing Taiwan's Only Large Aspheric Mirror" exhibition will allow the public to see for themselves this satellite-grade, internationally regulated optical component – something that could previously only be seen in textbooks – as well as the fantastic images that it can help produce. In addition, a reflecting telescope, which was invented by Isaac Newton, and a Maksutov telescope, invented by former Soviet optician Dmitry Dmitrievich Maksutov, are also on display, allowing children and adults to see the distant forest close at hand.

TIRI, in collaboration with NLPI, has organized several special exhibitions related to optics in the past. These include "Instrumentation Dream Factory: From Microscope to Space Telescope" in 2019, which allowed the public to get up close and personal with telescopes, as well as "Experts in Optical Solutions" in 2022, which put on display a large-aperture high-resolution optical microscope lens used for brain science research, which has helped scientists to more deeply explore the microscopic realm. This year, with the key optical component of a satellite optical remote sensing system – the large aspheric mirror – TIRI has launched its latest special exhibition. At this fascinating venue, visitors can explore how TIRI's optics experts analyze the art of space lens processing and measurement. All are welcome to come visit NLPI and learn about the imaging of a variety of telescopes, as well as understand how TIRI mastered the technology of large aspheric lenses and independently developed the primary and the secondary mirrors of a satellite remote sensing system.