Cross pollination

Dear Sir:

With regards to your editorial "Cross pollination" (Vision Systems Design Magazine, October 2013, p. 5), the original intent of Foveon when Carver Mead founded it was to build a studio portrait camera using a 3-channel prism and a custom 4k x 4k CMOS sensor that Foveon designed. However, it became clear that this was a limited market and so Foveon acquired the technology and set out to make a commercial device for the DSLR market. This sensor (the F7) was adopted by Sigma for their first digital camera, which was introduced in September 2002. We started selling that sensor in the industrial and scientific markets in October 2003 and have been doing so ever since. It is true that the Foveon sensors have never been widely adopted but we have sold cameras from HanVision and Quest into a variety of markets. Toshiba TELI designed and sold a camera with the smaller F19 sensor into the wafer prober market. The current sensor suitable for general use is the F13 for which the field of application is limited by its lack of a global shutter to imaging either stationary or strobed (or shuttered) objects. Even so, it has been used for document capture, several scientific instruments and, possibly most interestingly, in the CLUPI camera on the ExoMars vehicle to be launched by the European Space Agency in 2018.

The use of the sensor in digital cinema has been hampered by the single-output architecture of the existing Foveon devices. They are simply too slow for this application. The maximum scan rate for 720p is about 24 fps. At 1080p it is useful only for stills. There is no reason multiple taps could not be incorporated into the sensor design but they have not been demanded by Sigma so far. However, if someone needs enough devices that include global shuttering and multiple taps, those can be supplied.

David Gilblom, President, Alternative Vision, Tucson, AZ, USA

E-mail: [email protected], www.alt-vision.com