Colour and Near Infrared From The Same Sensor

[Mike Farley]

Olympus is developing a sensor which captures both colour and near infrared images simultaneously. While the technology has other applications, it would herald the end of expensive camera conversions to shoot infrared exclusively. That would be a great benefit for those such as myself who are into infrared photography and encourage more people to try it. Details at Amateur Photographer.

http://www.amateurphotographer.co.uk/la ... time-80006

Note that so called infrared photography does not record the infrared part of the spectrum, rather the light just beyond the red end of the visible spectrum which is known as near infrared. True infrared has a longer wavelength and is the next section along on the spectrum.

Digital sensors can already capture near infrared, but manufacturers use filters to block it as it alters colours and affects both metering and focus. Having scanned the white paper linked by the AP report, there is no mention of the last two points. With my own infrared converted camera, the metered exposure is just the starting point and the final exposure is often one or two stops different. Given that the dynamic range of sensors is around 12 - 13 stops, it would be possible to adjust the signal so that exposure would be correct for both the colour and near infrared images.

Focus is potentially more of an issue and might mean the development of new lenses. Current lenses are designed so that blue light at one end of the visible spectrum which has a shorter wavelength than red at the other end and all the wavelengths in between are brought to focus at the same point. This means that a focus adjustment is necessary when using a conventional lens to capture the longer wavelengths of near infrared. Convergence across the wider wavelengths from blue to near infrared would add to the challenges already faced by lens designers. One possibility is that this will simply be countered by utilising the increased depth of field characteristics provided by a smaller sensor to mask the problem.

As I reported recently, lenses themselves might be changing. Modern designs are essentially evolutions of glass based optics which have been employed for centuries. Maybe this will be an example of separate technologies coming together in a new kind of product. There is one thing which you can be certain of. If I have thought about the problems, those far more knowledgable guys at Olympus will be onto them and no doubt plenty of others as well.

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