Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
It's not just an LED, it's a Laser Diode, these produce coherent light, which the lens can then focus - a normal LED (or lamp) produces in-coherent light.
"Coherent" means there is only 1 principle wavelength produced, thanks to the quantum properties of the junction material. That's true for all LEDs exept for white, white are blue LEDs with a yellow-emitting phosphor.
"Coherent" means there is only 1 principle wavelength produced, thanks to the quantum properties of the junction material. That's true for all LEDs exept for white, white are blue LEDs with a yellow-emitting phosphor.
This is why I told him to do a Google search.
While it's true that LEDs produce only one principle wavelength, that is not the definition of coherence. Coherence means all photons are in phase. Lasers produce coherent light, LEDs don't.
I wonder if the "lens" of a laser diode is part of its internal reflecting mechanism that causes it to oscillate only at the single frequency where all waves are in-phase.
I wonder if the "lens" of a laser diode is part of its internal reflecting mechanism that causes it to oscillate only at the single frequency where all waves are in-phase.
I don't think so. **broken link removed** is a good article that explains the semiconductor laser structure.
I actually don't know squat about laser diodes.
If you connect a variable power supply to a cheap red laser pointer, and gradually increase the voltage from 3 volts, the output power will increase to a peak, then fall as voltage is increased further. It is quite safe from the laser's point of view to run at this peak, but watch the power dissipation in the series resistor. So far, best results are 7mW from a <1mW laser pointer.
While on the subject, if you look at a spot of laser light, you will see a grainy pattern, which will be in focus. If you put a lens over your eye, so that you can't see anything else, the grainy pattern will still be in focus. Only coherent light will do this.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
