ISRO has developed an optical imaging detector array for hyperspectal imaging capabilities from Earth orbit. Hyperspectral imaging captures pixel level information across the electromagnetic spectrum, beyond the wavelengths that the human eye can recognise. The development came about during the search for a suitable imaging payload for the Hyperspectral Imaging Satellite (HySIS).
The Vir-NIS payload is meant to capture hyperspectral images in the visible and near infrared regions of the electromagnetic spectrum. There are two related methods for obtaining hyperspectral images, push broom scanners and its variant, the whisk broom scanner. ISRO will be using the push broom scanning approach for this particular imaging instrument. The sensor is required to work from an orbit with an altitude of 630 km.
Initially ISRO wanted to use an off the shelf detector array from an international commercial supplier, but the shortlisted detectors did not meet the various requirements of ISRO.
So, the Space Applications Centre (SAC) and Semi Conductor Limited (SCL), an independent body under the Department of Space worked together for the indigenous development of a Frame Transfer Charge Coupled Device.
The SAC came up with the device design, chip layout, chip architecture and the package design. A testbench was also developed to check if the software, hardware and firmware were working as required. The resulting optical imaging detector array was successfully tested to meet the requirements of ISRO.