Laser/IR Ranging...Inexpensive, 25ft Range, Accurate

[woooooofa]

Thanks for having me, this is my first post!

I would like to create a distance/ranging device using an existing inexpensive (<$20.00) technology. I would just need to know the distance to ~1". The IR proximity sensors I had seen before (Sharp) max out at ~30 inches. I would need to increase the range considerably more than that, hopefully to about 15-25 feet (or at least 10). It is OK to have some sort of transmitter or reflector on the object to be distanced. Is there a way to boost the range on the IR sensors or would laser be a better option? Can I make/find a laser ranging system that is inexpensive enough? Thank you ever so much!

[jcx]

maybe you should keep it audio related - timing acoustic signals is practical at relatively low cost, light speed is a little more challenging

"Polaroid" ultrasonic rangefinders may do the trick, not likely to reach the cost until you commit to 10K+ qty (applies to almost anything really, be prepared to spend 10-100x for a one off of something not already mass produced for a large consumer market)

cooperative target helps a lot, maybe a ir flash to trigger a chirp from a polaroid transducer on the target, timing the one way acoustic pulse is easier due to better s/n over the reflective approach

non timing cheap optical -

ir leds on the target would appear really bright in a cheap webcam - with enough separation of the leds and proper optics it becomes a software problem to figure the distance from the separation of the leds in the image - modulate the leds and diff image frames for greater s/n

[davidsrsb]

1" resolution at light speed means about 100ps time resolution - not easy.
At audio it means about 100us.