This paper describes the combination of my hobbies, caving and holography.
Most traditional holography involves bringing the objects to a lab with all the necessary holography equipment mounted on a stable table. I instead bring all the equipment assembled as a portable unit to the natural formation objects in a cave with the cave itself being the stable table.
The first successes were Denisyuks made with a HeNe or laser diode and a spatial filter mounted on a tripod. For greater depth transmissions holograms were made with a DPSS laser in several configurations sometimes using fiber optics to route the reference beam and sometimes a spatial filter and mirrors.
The cave environment presents unique obstacles that have been overcome as evidenced by the beautiful holograms made.