ow I have several diffraction grating. This one. Here it is. And what I’m gonna do is I’m gonna bring it right up to the lens and you can see to the left of the light bulb, you can see a spectrum, the brighter of the two.

And if you look further to the left, you’ll see a fainter spectrum. That is more spread out. It’s fainter, but it’s more spread out. So generally diffraction grating will produce what’s called a first order. That’s the first one. to the left of the light bulb. And then a second order that is more spread out.

So that’s 550 lines per millimeter. This one here is 750 lines per millimeter. And you can see that the first order spectrum is very bright. In fact, the, the camera really isn’t capturing the colors. Very Well. ignore the, that spectrum kind of bouncing around at the faint one, bouncing around at the bottom.

We’re getting some reflections between the lens and the defraction grading, but the first order is so bright that again, the camera is not really recording the colors very well. And, but if you look off to the left about the left third of the frame, you can see the second order spectrum. I can even pivot here a little bit, so you can see the whole thing.

So more spread out than the first order. Notice that the red light is always the wavelength, always the color that is furthest from the light bulb or the source or the slit. And lastly, the third defraction grading, this one has 1000 lines per millimeter. So there’s the first order spectrum. And you can see it’s more spread out again, ignore that reflection at the bottom.

And here is the second order. Spectrum really spread out.

By the way, if you see those lines, either vertical or horizontal, don’t think that those are absorption lines. Those are just either artifacts from the little holders inside the light bulb, that’s holding the filament or, or fingerprints and whatnot on the diffraction grating.. We are not seeing any absorption lines in this demonstration.

They’re going to be really expensive. Now there are just flat out fun toys. Again, things like this, where you look through and you see rainbows and really that’s just meant to be cool.

But then there’s also going to actually be categories of natural phenomenon. Now the most important thing to recognize is that we’re really going to have one number that describes these. And this is going to be our lines per inch or per millimeter, per centimeter, per meter. Whatever this distance is can vary, but you have some sort of, of distance and you have a number Of lines and this number could be very big.

So this is really important. And normally when you buy a diffraction grating, this is the value that describes it.