Panoramic Multispectral Imaging photography is the method I use for art documentation as it’s fast and lightweight. I already published about it “A Practical Guide to Panoramic Multispectral Imaging” and I posted on this subject throughout my blog: “Panoramic Infrared Reflectography. Arduino electronics”, “Panoramic Infrared Reflectography for painting documentation”, “Gigapan, High Resolution Imaging made easy”
I’m addressing in this post the specific topic of lighting, specifically for Panoramic Infrared Reflectography. The idea is that we want to reduce as much as possible the amount of unnecessary radiation over the painting: ultraviolet light, visible light and thermal infrared radiation. On the other hand we want an high amount of infrared radiation in order to have a good infrared reflectogram.
So far the best lamps for infrared reflectography are the halogen ones. They emit plenty of the needed infrared light but, unfortunately, together with all the other unwanted radiations. A good improvement for the well care of the art investigated is to use a Sun light filtering screens. Indeed, they work pretty well at stopping the visible, ultraviolet and also the thermal radiation. So your painting is spared unnecessary radiation. This filters allow through the close infrared at least over 1500 nm (I tested this with a Thorlab 1500 nm filter on the InGaAs camera). As usual I made a little video and you’ll notice I’m switching to more modern sound tracks.