Infra Red Emittor and Collector

[Jones1987]

Do infra red rays spread out or do they work the same as lasers and fire in a single ray?

Example if I have the emittor at different distances from the object it is scanning (e.g a ground surface say 10mm and 30mm distances) do the rays spread and further to cover a wider range, or do they fire down straight no matter the distance?

Thanks.

 

[boneh3ad]

That depends on the emitter. Infrared light works the same way as visible light. It can be coherent as in a laser or diffuse like a flashlight.

 

[Dr Lots-o'watts]

Even lasers spread out. In general, every source does. It is a matter of design.

 

[Jones1987]

What are the tell tale signs of how the component is designed? How will I know if it is set-up to fire in a line, or create a spread?

This is the component I've been looking at:

http://www.active-robots.com/products/sensors/sensors-fairchild.shtml

 

[Dr Lots-o'watts]

It surely spreads to some degree, but it may not be relevant. The information you may need would be the intensity profile, or the intensity of the beam as a function of the exit angle. This should be some kind of bell shaped curve I(theta). What you are asking for is the shape of this curve. Only the manufacturer can provide such information (or anyone else who has the device and has bothered to the measurement).

 

[Redbelly98]

What are the tell tale signs of how the component is designed? How will I know if it is set-up to fire in a line, or create a spread?

This is the component I've been looking at:

http://www.active-robots.com/products/sensors/sensors-fairchild.shtml

That page has a link to http://www.active-robots.com/products/sensors/fairchild/qrb113x.pdf" which has a scale drawing of the part. Looks like the beam is emitted by an IR LED in a recessed hole. So the beam will have some angular spread, but there's nothing in the datasheet telling us how big that angle is.