A GSTP activity under the de-risk framework wanted to address the major risks associated with the manufacture of large area 2D curved sensors.
The use of a traditional flat image sensor requires optical elements to project the image onto a flat plane. Introducing the use of an appropriately curved sensor removes the need for these optical elements. By eliminating this constraint on the design of lenses it becomes possible to design systems with reduced size and weight and improved performance.
Currently, it is difficult to manufacture these large curved lenses as there has been no assessment of the viability of a 2D curving process, no development of the basic process and packaging concept, and little evaluation of what surface forms are achievable.
The activity, with Teledyne e2v Ltd in the UK, has verified that viable process to manufacture curved visible image sensors can be established, based on additional substrate thinning after advanced back thinning processing already in place at Teledyne e2v. The programme has included the development of jigging and packaging concepts and the selection of appropriate adhesives. The curvature targeted and achieved was of concave spherical form with a radius of curvature of 500mm for a 6cm by 6cm back illuminated CCD. Evaluation of a packaging concept for suitability for use with the proposed process has been undertaken successfully, and the accuracy of the surface form established. Electro-optical testing was outside the scope of this de-risk activity, although DC testing to confirm the electrical viability has been undertaken.
The activity showed that the number of lenses in Sentinel 5 would have been halved, reducing the number from 6 to 3, with the use of a sensor of the appropriate curvature.
Now, similar benefits should be possible for the camera systems for upcoming Copernicus missions.
G617-241TAay DE-risk: Curved Sensor closed in 2019.