Probably should just invent one, cause no one else manufactures anything close.
Everyone knows when checking the blower RPM, you need the blower access door closed to get an actual "under load" rpm.
Most of us will drill a hole in the access panel to point the laser through. I usually do this but it is a pain in the butt to sometimes get things lined up. Or many times blower pulleys are perpendicular to the door and just not possible.
If your reading FP...like to see a laser tachometer accessory head with multi-point magnets. This way I can position the laser pointing at the reflective tape, shut the blower door and see my RPMs live and under load conditions. I use the amp clamp accessory head with the wireless transmitter to get accurate "under load" blower motor amps with the door closed, wish I could just do a quick swap and get my RPM's.
Save a bunch of time when commissioning new equipment...heck you already have a non-contact laser temperature head, your not that far off from a non-contact laser tachometer.
Food for thought.