Wow, it has been a long time since I last posted!  Well, what has been a very busy uni year is over now, so I will try my very best to post a bit more frequently, at least until the next academic year starts!!  To kick off I thought I would describe how to put together an infra red light source.  I had a surprisingly difficult time finding what I needed to know to do this so I thought I would post what I found out in case it helps anyone else.  To prevent the post getting too long I have split it into two parts, the first just describing what I ended up deciding to do to in order to get hold of an infrared light source and in the next post I will describe how to actually put the thing together.

During the year I needed to film some of my experiments in complete darkness and so looked into getting some infrared lights.  There are a lot of web cams on the market that use infrared these days so I thought it would be easy. It turns out that there are two ways of producing infra red light.  One is to use a light source that produces light in the infra red part of the spectrum such as that produced by infra red LEDs, the alternative is to use a white light source and fit it with a filter to cut out all wavelengths except for infrared.

The latter could be done by buying long pass filter glass such as RG850 by Schott (eg www.galvoptics.fsnet.co.uk/rg850.htm) and having it cut to fit halogen floodlights from Bunnings (see picture below).

The floodlight only costs about $26.00 from Bunnings, but for one 165mm x 165mm sheet of RG850 filter glass, 3-4mm thick, cut into three 76×41mm pieces that would replace the glass in the floodlights, it would cost $779.90.  Why it needed to be so expensive is beyond me, but that is science for you.

Looking into infrared emitting lights didn’t seem that much better.  An exhaustive search didn’t turn up that many options.  The best were also quite expensive, though not as bad as the Schott filter glass.  A light capable of illuminating to ~30 metres was $US150, which wasn’t too bad.

My lab funding didn’t extend quite that far so I was looking at cheaper options and settled upon Infrared LED light sources.  There are security lights made with LED’s  (eg www.wirelesshouse.com.au/p1623/s932/IR_Lamp_PRH_5218) but those were still around $150.00.

Jay car had a smaller version (www.jaycar.com.au) which was only $49.95 but I thought only 18 LEDs would be a bit dim.

In the end I decided that it would probably be easier if I just made it my self.  I found the ideal kit at Oatley Electronics (oatleyelectronics.com) which was only $29.00 and let you build a 140 LED light source.  I decided to make 2 so I bought two of those.

The kit came with only 35 LEDs that emitted light at 880nm.  I had tested the camera I was going to use (a JVC Everio GZ-MG30 hard drive camera) and 850nm seemed to be picked up better by the CCD chip, so I also bought 280 x 850nm LEDs from Futurlec (www.futurlec.com) which cost $65.00 ($56.00 for the LEDs, $9.00 postage)

So that is how I came to be building my own infrared light source.  Part two of this post will be instructions on how to assemble the kit.  This is both to explain to those interested how it is done, but also because  as a result of some confused marketing decision there were no instructions with the kit itself…

The second part of this post can be read here.