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Building a multispectral infrared camera: my visit to Andover Corporation

Deanne Rogers

by Deanne Rogers

Assistant Professor of Geosciences at Stony Brook University.

As someone who is usually sitting in front of a computer, making interpretations about remote planetary surfaces using spacecraft data, I am particularly excited for the chance to apply my skills on the ground in a real field environment. One of the main objectives of RIS4E Theme 2 is to test out a variety of hand-held scientific instruments in the field, with the goal of making informed recommendations about which instruments will be most useful for astronauts when choosing rock samples and documenting their context. For me, this will be an exciting chance to make a contribution towards the success of future human exploration of our solar system.

Testing out field instruments and carrying out sample collection involves a series of steps, beginning with analysis of satellite infrared imagery, followed by ground-based spectral imaging, and then “contact” measurements of rock chemistry and mineralogy (where the instruments actually touch rock surfaces). Most of our equipment is already in possession by our team, but one item we lacked is a multispectral, thermal infrared camera. Multispectral infrared imaging allows us to distinguish different rock types much better than we can with our eyes. Many rocks are shades of black and brown, but despite similar colors, their compositions can be very different! Using infrared imagers, however, different rock types appear as different “infrared” colors. With handheld spectral imagers, astronauts exploring planetary surfaces should be able to more quickly and easily find the most interesting as well as the most representative rock types.

View of Hawaiian lava flows in visible color (left) and in multispectral thermal infrared color (right). Data are from Digital Globe and the Thermal Infrared Multispectral Scanner.

View of Hawaiian lava flows in visible color (left) and in multispectral thermal infrared color (right). Data are from Digital Globe and the Thermal Infrared Multispectral Scanner.

To save on costs, rather than purchase a new multispectral imager, we decided to retrofit an existing thermal camera with custom-made thermal infrared filters of differing wavelengths. By taking multiple images of the same location, switching out filters in between, it should be possible to build a multispectral image of the scene of interest. After researching several companies, I chose Andover Corporation, based in Salem, NH, to manufacture the filters.

Because the design engineers had never produced filters for my particular camera model, there was some initial uncertainty about how the filters would actually attach to the camera. I decided to travel with the thermal camera to Andover for a day, and meet with the design team. When I arrived, I met with my technical sales contact in the lobby, received a visitor’s badge, and walked with him to the conference room. I was introduced to five enthusiastic engineers, and asked to describe my needs and expected use for the filters (It turns out, that group of five engineers included both the president and vice-president of the company! It was not until lunch, an hour later, that I realized this.)

The engineers talked excitedly about possible ways to attach the filters – I’ll skip the details, except to say that it was fun to have a chance to talk with such a creative group of people. After lunch, the company president, Richard Bennett, gave me a tour of their facilities. (Thankfully, by that time, I had realized who he was). The highlight of the tour was peering through the windows of one of their vacuum chambers and seeing a substrate coating in progress (to make the filters, they have to put thin coatings on glass-like material so that only certain wavelengths can pass through). This image should give you an idea of what I saw through that window. They use several different processes, this one in particular was “magnetron sputtering”. I also learned that essentially all steps involved to produce the filters are done in-house, from the substrate production, coating process, quality control and testing. They also manufacture all of their own vacuum chambers, which are quite large. Needless to say, I was very impressed!

Deanne shows off one of the infrared camera filters manufactured by Andover Corporation.

The filters just arrived this week.  Stay tuned for some multispectral thermal infrared science!

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