viewer challenge - Laser Distance Measuring

Hi Neil,

Laser distance measurement uses time of reflection (TDR) or phase of reflection or a combination of these methods.

Time domain refectometry is pretty straight forward conceptually - send a pulse out and measure the time for it to be reflected back. To measure the time is mainly a matter of counting pulses from an internal clock of known frequency.

Another method uses lasers reflecting onto a camera which computes the distance by triangulation.

Light travels roughly 30 cm per nanosecond so a 1 GHz clock only provides 30 cm of resolution using TDR. You could start by looking through component catalogs from the fibre optics industry since they are switching lasers a rates in excess of 10 GHz, and they have detectors that operate at these rates as well.

It will likely be hard to find a cookbook circuit to perform this function at these frequencies since physical layout is as critically important as the circuit components, so count on a bit of a learning curve to design a workable system.

The cost of suitable components is coming down as evidenced by price drops in commercial range meters, but it may be a while before you can find an inexpensive laser TDR module that would just plug into an Arduino.

You can find used optical TDR instruments for a couple of hundred dollars, but the are designed to work with fibre optics, not free space, and laser range meters are already cheaper than this.

There are certainly many applicatins for distance measurement so the cost will continue to come down, maybe we will see inexcpensive LIDAR modules soon, since they are becoming so popular on robots. I hear there is already a inexpensive LIDAR in one of the vacuum cleaner robots. See this article:

http://www.hizook.com/blog/2009/12/20/ultra-low-cost-laser-rangefinders-actualized-neato-robotics

Have you thought about usng the Microsoft Kinect technology for dimensional measurement?

Here is a reference to a group who think they have a $30 LDS solution:

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=4543666

Doug

Hi Neil,

Doug is correct, the timing is critical.  What kind of ranges are you hoping to captured?

For small areas, you might want to go with an ultrasonic system, readily available from many vendors.

A laser can be very precise, but be aware that the spot size is small, so to map a large area, you will need to do a lot of measurements to accurately capture the whole area.

Just a thought,

DAB

Was looking for 100m at least

I want to get into arduino and thought this might be a good project for me once i've learnt the basics,  then i thought might be nice for ben to do   Company won't fork out for a new one so was thinking build for cheap if possible.

Hi Neil,

As I stated before, timing is critical.  Unless you have a big budget, I would buy one before I tried to make something that precise.

DAB

Hi Neil.  Were you able to come  up with something cost effective that can measure distances upto 100m?

No

In the end I didn't bother making room plans.