Researchers devise new membrane mirrors for big space-based telescopes | Information Releases

4 April 2023

Researchers devise new membrane mirrors for big space-based telescopes

Light-weight versatile mirrors might be rolled up throughout launch after which exactly reshaped after deployment

WASHINGTON — Researchers have developed a brand new approach to produce and form massive, high-quality mirrors which might be a lot thinner than the first mirrors beforehand used for telescopes deployed in house. The ensuing mirrors are versatile sufficient to be rolled up and saved compactly inside a launch car.

“Launching and deploying house telescopes is an advanced and expensive process,” stated Sebastian Rabien from Max Planck Institute for Extraterrestrial Physics in Germany. “This new method — which could be very totally different from typical mirror manufacturing and sprucing procedures — may assist resolve weight and packaging points for telescope mirrors, enabling a lot bigger, and thus extra delicate, telescopes to be positioned in orbit.”

Within the Optica Publishing Group journal Applied Optics, Rabien experiences profitable fabrication of parabolic membrane mirror prototypes as much as 30 cm in diameter. These mirrors, which might be scaled as much as the sizes wanted in house telescopes, had been created through the use of chemical vapor deposition to develop membrane mirrors on a rotating liquid inside a vacuum chamber. He additionally developed a way that makes use of warmth to adaptively appropriate imperfections that may happen after the mirror is unfolded.

“Though this work solely demonstrated the feasibility of the strategies, it lays the groundwork for bigger packable mirror methods which might be inexpensive,” stated Rabien. “It may make light-weight mirrors which might be 15 or 20 meters in diameter a actuality, enabling space-based telescopes which might be orders of magnitude extra delicate than ones at the moment deployed or being deliberate.”

Making use of an outdated course of in a brand new means

The brand new methodology was developed through the COVID-19 pandemic, which Rabien says gave him some further time to suppose and check out new ideas. “In a protracted collection of exams, we researched many liquids to seek out out their usability for the method, investigated how the polymer progress will be carried out homogeneously, and labored to optimize the method,” he stated.

For chemical vapor deposition, a precursor materials is evaporated and thermally cut up into monomeric molecules. These molecules deposit on the surfaces in a vacuum chamber after which mix to type a polymer. This course of is usually used to use coatings corresponding to those that make electronics water resistant, however that is the primary time it has been used to create parabolic membrane mirrors with the optical qualities mandatory to be used in telescopes.

To create the exact form mandatory for a telescope mirror, the researchers added a rotating container full of a small quantity of liquid to the within of the vacuum chamber. The liquid varieties an ideal parabolic form onto which the polymer can develop, forming the mirror base. When the polymer is thick sufficient, a reflective steel layer is utilized to the highest through evaporation and the liquid is washed away.

“It has lengthy been identified that rotating liquids which might be aligned with the native gravitational axis will naturally type a paraboloid floor form,” stated Rabien. “Using this primary physics phenomenon, we deposited a polymer onto this excellent optical floor, which fashioned a parabolic skinny membrane that can be utilized as the first mirror of a telescope as soon as coated with a reflecting floor corresponding to aluminum.” 

Though different teams have created skinny membranes for related functions, these mirrors are sometimes formed utilizing a high-quality optical mildew. Utilizing a liquid to type the form is way more reasonably priced and will be extra simply scaled as much as massive sizes.

Reshaping a folded mirror

The skinny and light-weight mirror created utilizing this method can simply be folded or rolled up through the journey to house. Nevertheless, it could be almost unattainable to get it again to the right parabolic form after unpacking. To reshape the membrane mirror, the researchers developed a thermal methodology that makes use of a localized temperature change created with mild to allow adaptive form management that may carry the skinny membrane into the specified optical form.

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The researchers examined their method by creating 30-cm diameter membrane mirrors in a vacuum deposition chamber. After a lot trial and error, they had been in a position to produce top quality mirrors with a floor form appropriate for telescopes. Additionally they confirmed that their thermal radiative adaptive shaping methodology labored properly, as demonstrated with an array of radiators and illumination from a digital mild projector.

The brand new membrane-based mirrors may be utilized in adaptive optics methods. Adaptive optics can enhance the efficiency of optical methods through the use of a deformable mirror to compensate for distortion in incoming mild. As a result of the floor of the brand new membrane mirrors is deformable, these mirrors might be formed with electrostatic actuators to create deformable mirrors which might be inexpensive to make than these created with standard strategies.

Subsequent, the researchers plan to use extra refined adaptive management to review how properly the ultimate floor will be formed and the way a lot of an preliminary distortion will be tolerated. Additionally they plan to create a meter-sized deposition chamber to higher research the floor construction and packaging and unfolding processes for a large-scale main mirror.

Paper: S. Rabien, “Adaptive Parabolic Membrane Mirrors for Massive Deployable Area Telescopes,” Utilized Optics, vol. 62, problem 11, pp. 2836-2844 (2023).

DOI: https://doi.org/10.1364/AO.487262

Utilized Optics

Utilized Optics publishes in-depth peer-reviewed content material about applications-centered analysis in optics. These articles cowl analysis in optical expertise, photonics, lasers, info processing, sensing and environmental optics. Utilized Optics is printed 3 times per 30 days by Optica Publishing Group and overseen by Editor-in-Chief Gisele Bennett, MEPSS LLC. For extra info, go to Applied Optics .

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