Custom CCD Image Sensors
In the late 1990s and early 2000s, high performance CCD image sensors were not very common. The Jet Propulsion Laboratory had design, packaging, and test expertise, but was looking for a wafer foundry to build a custom CCD image sensor that would fit the application.
In terms of process, Teledyne DALSA engineers went with a conservative and simple approach, with just enough innovation to get a high-performance CCD without taking risk for reliability. For example, minimum feature size was not pushed to the limit, and material selection for some layers was made to avoid potential reliability problems. CCDs were chosen because they are a robust technology and are qualified for space travel. The CCD is well known for its superior image quality, which is often preferred over speed.
Eventually custom design was matched to custom process, to build 1k by 1k frame-transfer CCDs. After approximately three years of development, a batch of CCDs was made, and they passed all tests for the Spirit and Opportunity rovers.
Custom-manufactured CCD image sensors from Teledyne DALSA proved their reliability in these previous Mars Exploration Rover missions, and the components were chosen once again to function as the imaging technology for the Curiosity rover’s navigational eyes.
Teledyne DALSA engineers reviewed the design with NASA engineers, proposed changes, made masks to build the devices, and fabricated and tested the wafers. Then the wafers were sent to NASA, where the CCD was tested and assembled.
The Mission Continues
The Curiosity rover has captured the minds of many, and even has its own Twitter and Facebook accounts to share information and photos via social media. Signals from the Curiosity’s cameras take about 14 minutes traveling at the speed of light to reach Earth, and then they must be downloaded and processed. Amazingly, these images can be shared very quickly with the public.
Soon after the landing, the Curiosity rover started looking around at its environment and sending images back to Earth. As this mission to Mars continues to search for past or present conditions favorable for life, the imaging components on the rover support the exploration by helping the Curiosity to safely navigate the Red Planet’s surface.
This article was written by Robert Groulx, CCD Product Engineer, and Raymond Frost, Senior Process Integration Scientist, at Teledyne DALSA Semiconductor (Waterloo, Ontario, Canada). For more information, visit http://info.hotims.com/40440-142.