Just some ideas off the top of my head:
Maybe construction? I'd think it would be really useful to have a good range finding/measurement system when doing almost any kind of construction. If you could get a really good set of measurements of, say, inside of a kitchen, then you could build new cabinets at a shop (saving money vs. building them on site) and then install them with out worrying about how well they fit.
Would it be useful in emergency situations? Woodland firefighting in particular -- could it be mounted to the front of a helicopter and used to keep track of where the fire is, and how it related to the terrain? Then it all gets mapped out, along with the GPS coordinates of firefighters and equipment and you'd have a good emergency incident command system.
Could the diffraction grating idea be used to improve FLIR systems?