Simple Laser range finder

Cyparagon said:

First post asking for entire blueprint to rangefinder? Not gonna happen, sir.

I won't say it's impossible to built one from scratch, but it's a very advanced project. Might I suggest building a pointer or projector first?

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Sigurthr said:

If you're just going to point at random things and measure the distance I have no idea, but if you wanted to measure the distance of a fixed target I think you could do it somewhat "easily".

You can use a one-shot to simultaneously trigger a short pulse to the laser and a count down start (or even a reset - even easier) to a simple binary counter driven by a high frequency oscillator. Feed the receiver's HI output (which indicates the return pulse has arrived) to the counter stop (can be a simple soft latch that holds the binary counter's oscillator input high). Read the counter's state and multiply by the time period of the oscillator, then divide by the speed of light in air and then divide by two. I have no idea what frequency you would use, you would need to determine how long a pulse should take and work out a frequency which will have enough clocks for good resolution but not so fast that you risk the counter resetting or timing out. Most simple counter ICs max out at 8192 time periods. You also need to be mindful of any propagation delays in your signal paths and logic.

Good luck, you'll need it!

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Sigurthr said:

I don't know of any modules, though I don't doubt there are some available commercially. Heck, I think they make range finders for golfers and land surveyors.

Schematics would be a bit above what I could reliably do; I've only recently begun working with timer ICs (not counting the 555 of course) and there is a lot more info and research needed to take the basic design theory that I posted and put it in to a schematic.

Not that we don't have some members who might be capable of this kind of device but why don't you look to an electronics forum for help with this? The Laser in this device is such a minor part that for all intents and purposes it could be replaced with an LED and the circuit would work electrically the same (sans no return signal of course). In other words, find help with the main part of the citcuit elsewhere then come here and find the laser specific info you need.

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bogalark said:

hi
if not complete schematics of individual components can i get the readily available modules so that i can integrate them to get a laser range finder like 1).laser diode transmitter which includes the laser diode(CW or PW) including the collimator and the laser diode driver
2).laser receiver which includes receiver lens,photo diode and conversion unit(i am not sure, i mean light signal to voltage(electrical signal)).
3).time descriminator/ time to digital converter for measuring the time between start pulse and received pulse(any microcontroller/chip).

if yes, for measuring a distance of 70 mts, can anyone specify the specifications that are appropriate to make a module..

thanks in advance...

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