Would infrared photography help enhance details in old tombstones?

I doubt it, because the carvings won’t have differentiated heat signals from the rest of the stone.

I would think you would have more success using a technology similar to Ground Penetrating Radar, which has applications in a variety of media, including rock, soil, ice, fresh water, pavements and structures. In the right conditions, practitioners can use GPR to detect subsurface objects, changes in material properties, and voids and cracks.

A very sensitive form of this technology should be able to pick up the subsurface and peripheral disturbances caused by the impact when data was carved into the stone, thus defining the surface characters that have been eroded by the elements.

Rather than light, a GPR transmitter emits electromagnetic energy in the form of high-frequency (usually polarized) radio waves within in the range 10 MHz to 1 GHz, aka the “microwave” band.

Would it help to take photos from several angles and try to combine them attempting to get more definition in the carvings?
@Espiritus_Corvus something similar to Lidar perhaps? Bet that equipment is cheap!

@rojo Lidar would be helpful in constructing imagery by detecting the differences in depth of the worn surface characters vs. the surface itself. This would be worth looking into.

I’m still stuck on the GPR idea and it has led to some interesting stuff in the last hour or so. Commercial GPR units cost in the tens of thousands of dollars. However, if you were feeling McGiverish, theoretically you could make a GPR system from an old microwave oven’s generator, focus the radio waves with a 4N25 opto-isolator, read the signals with a… I’m way out of my depth here, but here’s the description of the project and here’s a google page with a bunch of pdfs, etc., on similar projects. The five main electronic components used to build one of these are small and cheap—compared to the cost of a commercial GPR system.

The deal is this: microwave ovens typically generate at 2.45Ghz which isn’t great for depth, but will penetrate rock to about 12”, which is perfect for your purposes. One of the papers I read while researching this stated, “The most difficult part in building and operating a GPR is the signal processing of the reflected signals and not the transmitter.”

There was also this unsurprising warning:
CAUTION: 2.45 GHz can penetrate the human body and powers at the level produced by microwave ovens are dangerous to human tissue and internal organs, especially the eyes which can turn cloudy when heated as egg whites do.

They show you how to build an effective protective casing for the generator.

I love the net. Idiots like me can now get the info to re-use trash in projects that can lead to a new realm of learning experiences, whether that project succeeds or not. With very little money, the net, YouTube videos, related pdfs, and overnight delivery, anyone can go into their garage and become a mad scientist – and possibly learn how to re-use and convert valuable parts that are thrown away all over America on daily basis into viable, cheap, practical instruments and maybe even start a small niche business.

Ha. I think I’ve had enough coffee for today.

I think black and white photos would be better, diffused light, no shadows.

Infrared does not need heat. Different surfaces reflect the light differently. Vegetation is very light (it reflects infrared well), so there is possibility that it might help on the headstones.

Example here:“https://commons.wikimedia.org/wiki/File:Rudin-house.jpg”

Also, colored filters may help with a regular black & white visible light photo. A green filter would make the green moss and algae look lighter, a red filter would make them darker.

I’m not sure if this will help, but I’ve seen some rubbings of old headstones that seemed to bring out some details that were not apparent by just looking at the marker itself.