Astronomy & Space Sciences
Title : | Development of 1.2-meter aperture CFRP mirror for visible/optical wavelength application |
Area of research : | Astronomy & Space Sciences |
Focus area : | Composite Components Development and
Fabrication |
Contact info : | jaimin_desai@sac.isro.gov.in |
Details
Executive Summary : | Space based camera uses Telescope that consists of Reflective mirrors. It is the prime goal for any space based camera/telescope to be of light weight coupled with ease of Assembly, Integration and testing. SAC unit of ISRO at Ahmedabad is mainly responsible for the development of space based earth observation cameras with varied applications for missions like Chandrayaan, Mars orbiter mission, INSAT VHRRs, Cartosat series, Resourcesat series, OCM series etc. The space based telescope needs the mirrors with high dimensional stability (insensitive to temperature excursions- almost zero CTE- co-efficient of thermal expansionmaterials). We have been using Zerodur as glass mirrors materials of construction. This material is low CTE material but has disadvantage of very poor strength with high brittleness, which adds to the long realization time. With the increased high resolution requirements of the order of 1 meter and better, the main aperture size of the telescope increases, which adds to the weight and fragile materials (Zerodur Glass) handling complexity. CFRP- carbon fiber reinforced plastic- is a special type of material with Carbon fibers being used as a structural – load carrying member. The Carbon fiber at an individual level is having low and negative CTE of the order of @ (-2 to 0) X 10-6 /cent. By properly mixing matrix and carbon fibers, we can achieve near zero CTE. CFRP is a light weight, high stiffness, high strength material apart from low CTE material. Thus, CFRP is a prime candidate and is a material of construction for optical mirrors being used in present days. Surface figure/profile accuracy requirement for 1.2meter primary aperture is Lambda/20 rmsand @ Lambda/6 p-v at 633 nm. The surface roughness requirement is up to 2 nm maximum. The values are kept coarse at the initial stage, however, after gaining confidence from process and other parameters point of view, the final value shall be communicated which shall be more stringent. |
Co-PI: | Shri Jaimin Desai, Space Applications Centre (SAC), Ahmedabad |
Organizations involved