The leaves are telling you otherwise
Look at the picture you posted. ONLY the top leaves are thin and tacoing. The ones just below it are wide and perfectly fine... likely because they are further from the heat source. And im sure you'll notice that same trend if you look at the plant itself... the leaves at the bottom are fine, leaves up top are much thinner, and the ones at the very top are the ones tacoing.
Yes.. the "laser" thermometers are optimal for getting surface temperatures. But even if you don't have one, just move your lights up some and see what happens. If your at 18in now, id go up another 6in, give it a week and see what happens. If the leaves aren't brown/crispy they'll flatten out. If they're cruspy, they'll likely stay tacoed regardless.
Do me a favor though. Go to the app store and download the "Lux Light Meter" app, then tell me what your lux readings are at canopy height. The smart phone lux meters aren't super accurate, but should help give us an idea of where your at. I had someone test it against an actual lux meter and it was only a few thousand off, so while it isn't perfect, its a convenient way of seeing light intensity at different heights/areas