Multi-Mode laser diodes.

[VioletBeam]

What is the difference between a single-mode laser diode and a multi-mode laser diode.

I don't want to get reply's saying, "the particle of the photon is combined in the multi-mode creating a casterum" I want somthing that I CAN understand.

[Doc]

In simple terms; multi mode diodes emit light at more than one wavelength (colour). This makes the light less coherent and increases divergence (beam spread).

[tocket]

It depends on in which direction the mode is. Most of us are only concerned with the transverse mode (TEM). The TEM is optimally single mode, that is 00. Any higher TEM means that the laser is in fact giving several beams. For example TEM01 or TEM10 means there are two beams. These are multimode. There is a nice illustration of even higher orders here: http://en.wikipedia.org/wiki/File:Hermite-gaussian.png

As for the practical implications of transverse mode, you'll probably want your lasers to be single mode if you're doing scanned graphics. For beams however, I think multimode is OK. Depending on the optics of your laser you might not even see it is multimode.

There's also a longitudinal mode, but you don't need to concern yourself with it as long as you're only building laser projectors. Single longitudinal mode means there's only one wavelength emitted. Multimode lasers emitt multiple, tightly spaced, wavelengths.

[VioletBeam]

It depends on in which direction the mode is. Most of us are only concerned with the transverse mode (TEM). The TEM is optimally single mode, that is 00. Any higher TEM means that the laser is in fact giving several beams. For example TEM01 or TEM10 means there are two beams. These are multimode. There is a nice illustration of even higher orders here: http://en.wikipedia.org/wiki/File:Hermite-gaussian.png

As for the practical implications of transverse mode, you'll probably want your lasers to be single mode if you're doing scanned graphics. For beams however, I think multimode is OK. Depending on the optics of your laser you might not even see it is multimode.

There's also a longitudinal mode, but you don't need to concern yourself with it as long as you're only building laser projectors. Single longitudinal mode means there's only one wavelength emitted. Multimode lasers emitt multiple, tightly spaced, wavelengths.

I found this.

. This optic can correct the output of a multimode laser diode to a usable beam. You can bring it in the rest of the way with a simple long focal length lens. If you are willing to accept a half inch beam diameter you can get <1mr laser pointer like divergance perfectly usable for red light beam displays! The collimator is designed for medium power applications over 500mW to 15W and will turn the highly divergant beam from a diode laser into a beam perfect for lightshow display!

So does that mean that The multi-mode laser will have LOTS smaller diverage and tem00?

[tocket]

The mode is determined in the cavity, so external optics will not change it. You can of course change the divergence, but as you see, at the cost of beam diameter. The big question is, how do you fit such a large beam on your scanner mirrors?

[VioletBeam]

The mode is determined in the cavity, so external optics will not change it. You can of course change the divergence, but as you see, at the cost of beam diameter. The big question is, how do you fit such a large beam on your scanner mirrors?

I was thinking of putting it in a mendrith glass, and I'm not using it as a scanner, I'm using it as a Labby.