Syntax

First time posting here, just wanted to say hi, and maybe get a little help with a project.

ok i've been thinking about doing a project with some type of laser detection. The basic idea is to have a laser, and have a robot go to the laser. kind of like the light following robot, but more the light is going to be more specifically a laser.

Now i've been searching online but i'm having some trouble here, with detecting the laser.

Ok first off i need some way of detecting the light. I plan on using a visble laser, like a laser pointer, i think the frequency is something like 650nm.
So can i use a phototransistor and a filter?, to get just the frequency of light from the laser. Then set up like a 2 on my robot and use them as "eyes". I planned on running the output of the filter into an Analog to Digital input on my microcontroller. From there i can write the code to control everything else i need.



Also this is something i've been thinking about, now with the above mentioned plan, i was planning on haveing the robot go to the specific spot that the laser is originating from, specificly have the robot come right to the laser pen. But would it also be possible to say point the laser at the wall and have the robot see this as the target it needs to go to. So could the Phototransistors pic up on the reflection of the laser as if it where the laser starting point itself?

I'm a computer enginneering, but i'm still working on my EE skills, so any help would be great. Setting up the filter might cause me a bit of trouble too.

thanks for you time
-zac

Scubasteve

Hey,

This shouldn't be very difficult. Try to find a photodiode that is sensitive to that wavelength (650nM~), or it is possible to buy these, but they are quite expensive for the ones I have seen.

There are a few ways of doing what you want.. You can do the two 'eyes' idea which you can compare the intensity to eachother, when they are equal (after steering towards them), the laser is straight ahead.

You can spin a single photodiode in a circle, which will give you a sort of sonar-like system. This has the benefit of being unidirectional, but more complex.

If you want to be extremely hardcore, you can use a CMOS camera sensor and the filter in front of it. This will work like regular vision, but you will need two for depth.

Steve

Syntax

hey thanks for the reply man,

I hadn't thought of spinning the diode, that solves a problem i would have using just 2 photodiodes, find the light if it was behind the robot. Could be kind of interesting.

The CMOS camera sensor sounds awesome, but probably a little beyond the scope of my skills right now, and probably a little over kill for what i want to do. But i'll keep it in mind for later projects.

Thanks steve
-Zac

Scubasteve

If you need any help putting the peices together, don't hesitate to ask, I will help you as much as I can

Steve