UV line follower?

J

Jeremy Leach

Senior Member
This is just out of curiosity .... has anyone here thought about or done this : use a UV 'inivisible' Marker pen to draw the line, and UV LEDs and phototransistors to detect the line?

Was just thinking it might allow robots to navigate over areas where visible lines might not be acceptable. Plus it could change the bot/human relationship because the bot would be able to 'see' lines we can't !

I guess there might be health and safety issues of using UV ...but not sure how significant these would be, if at all.
 
B

BeanieBots

Moderator
Interesting idea.
One problem (besides those you mention) that I would guess at is light intensity from whatever 'marker pen' is used would be very low and in the visible spectrum. This would present some challenges in the detection. Filtering and modulation would help.
It would certainly add an interesting 'twist' to something like a school demo. Well worth doing some tests.
 
M

Michael 2727

Senior Member
I have a feeling that IR has much better reflection properties than UV.
IR seems to have been chosen as an industry standard for many light
sensing applications, this may be the reason, I could be wrong.

Then there is the cost factor, IR light is very easy to produce and to detect.
IR emitters can be a simple hot wire filament through to LEDs, whereas UV
can be difficult to produce and detect.
The introduction of UV LEDs has now changed everything ;)
I think the first LEDs ever produced were IR types ?

As BB said, the light reflected from a (my) UV pen is not very bright.
(and does not work well on many surfaces and coloured materials)

Anyway it could be interesting experiment :)

Some interesting pages below-

RS Data sheet for LDR PN- NORP12
http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/25/LDR_NSL19_M51.pdf

Colour/Color wavelengths-
http://www.cals.ncsu.edu/course/ent425/tutorial/colorvision.html

Infrared and ultraviolet imaging with a CMOS sensor-
http://www.alt-vision.com/documentation/5301A-25.pdf
 
I

InvaderZim

Senior Member
As an aside, I've heard you need to be careful when working with UV LEDs; you can't see how bright they are (so you'll never blink), but they *can* hurt your eyes if you look into a bright one. The warnings I read made them sound worse than IR LEDs.
 
A

Andrew Cowan

Senior Member
As long as you don't stare into them, or look directly into them for long periods of time, they are safe. The dangerous things are IR lasers.

Andrew
 
You must log in or register to reply here.
Top