What technology is in a laser range finder - please help

[sean]

Hi,

I am attempting to develop a simple prototype that detects objects moving towards it from a distance of 100 to 200metres (300Yards+) away.

The system doesn't need to be particularly amasing or give distance data, it simply needs to understand that an object the size of an average car is moving towards it.

My issues are that I need to get a basic prototype working for less than $40 with all the technology, it seems in terms of distance performance and cost, the technology present within a laser range finder should be suitable.

I have bought a laser range finder - these are products can be bought for as little as $150 and can operate to a mile or more.

I am trying to simply understand what technology is required to make a crude one of these, i.e. what is the actual transmitter / receiver electronic product part number I need to purchase, or what control system / PCB schematic should I be working with.

If you can help, that would be much appreciated.

Thanks,
Sean,

 

[davenn]

motion detection is done by the doppler shift method. ie. the system compares the freq of the transmitted laser beam with that of the received beam reflected from the moving object. The change in freq is going to be VERY small and will be proportional to the speed of the moving object.

$40 ... probably not $100 maybe. the main cost will be in the receiving and comparator part of the system.

the range finder is maybe a little easier as all that is being done is timing the return time if the reflected beam to find distance. Dont forget the price is ONLY ~ $150 cuz the units have been massed produced... it brings the price down

Dave