Tuesday, 27 February 2018

Artistic thermography

I have always wanted to have the opportunity to take images with a high resolution thermal camera. Some time ago I did do some shooting with the small Flir thermal imager that fits onto an iPhone, the Flir One, but this only has a thermal resolution of 80 by 60 pixels. My chance to experiment with a higher resolution device at IBC was thwarted by the courier company who sent it to Brussels instead of Amsterdam.

So in full envy mode I saw an excellent set of thermal images in the Guardian today. It's not easy to be artistic given the nature of the bizarre world of the far infrared, but photographer Grey Hutton has done just that. He also understands just how far infrared radiation behaves ... and, no, you can not see through walls or even glass.

I recommend you look at his images, both on the Guardian web site - Traces of warmth: thermal images of London's homeless - and his own website at www.greyhutton.com. He promises some thermal images from Berlin later, so we should keep checking. To be honest, his are the best artistic thermal images I have ever seen, and a poignant way to document homelessness at a really cold time.

In a similar vein I also found 328 of Joseph Giacomin's thermal images on the Getty stock photo site. If you search for infrared on the Getty site you will find quite a few nice images, mostly near-infrared. Here is one of Joseph's:

Embed from Getty Images

It looks as if the game is afoot for artistic thermography, despite the equipment being tens of thousands in cost. Glad to see it.

[March 21st: Grey's images from Berlin are now on his web site]

Monday, 26 February 2018

Near infrared optical coherence tomography

I recently had a bit of a false alarm, or a false positive in data terms, with my eyes. A routine eye test threw up a structural condition that could result in glaucoma and so I was sent off to visit a specialist eye clinic. As I said, the problem wasn't actually there, but in the course of the test I came across a use of near-infrared light that was new to me: OCT or Optical Coherence Tomography.

The test experience was somewhat like that slit-scan sequence from the movie 2001, with me seeing moving rectangles and triangles expanding and contracting in my field of view. The result was a cross-sectional view of my retinas looking something like this:

This is an OCT scan of the cross-section of a retina at 800nm with an axial resolution of 3µm. Near infrared will easily penetrate a few millimetres into human tissue and by using a pulsed laser and a lot of computing an image of this type (described as being like 'visual ultrasound') can be built up. If you want to see the techicalities (and some maths) then check out the Wikipedia entry. The particular equipment used for my test was by a company named Optovue.

[Image is copyright: GNU-FDL, origin medOCT-group, Dept of Med. Physics, Med. Univ. Vienna, Austria, 2004 via Wikipedia]