505nm diode?

[CurtisOliver]

I like the sound of that Diachi.
We can wish Paul. Even 502nm would look quite different.

 

[diachi]

I like the sound of that Diachi.
We can wish Paul. Even 502nm would look quite different.

There is a slight difference for sure.

500nm

502nm

505nm

515nm

Of course, a computer monitor won't reproduce the colours exactly, but you get the idea.

 

[CurtisOliver]

They are all so beautiful.
I can't remember who it was, I think it was lazeerer, that had a video of 498nm.
It was sure a nice wavelength. So rare as well.

 

[diachi]

They are all so beautiful.
I can't remember who it was, I think it was lazeerer, that had a video of 498nm.
It was sure a nice wavelength. So rare as well.

Added 505 and 515 to my comparison above.

Yes, that is rather rare, at least these days. Although you can get 497nm and 502nm from a multiline argon. :beer:

 

[CurtisOliver]

Thanks Diachi, could be useful for those wanting to compare.
I've only got a single line argon.
But anyway, when I finally get round to it 488nm will be great.

 

[Eracoy]

If I want to buy a few and find the shortest wavelength among them, what would be a realistic way to spectro these? I would love an excuse to buy a spectrograph (and honestly might if this pans out) but want to know if a handheld analog spectrograph with a scale can give me the resolution I would need. I would use a diffraction grating, but would prefer something with a built in calibrated scale. What would you guys recommend as far as nm-ish resolution measurement?

 

[ElectricPlasma]

If I want to buy a few and find the shortest wavelength among them, what would be a realistic way to spectro these? I would love an excuse to buy a spectrograph (and honestly might if this pans out) but want to know if a handheld analog spectrograph with a scale can give me the resolution I would need. I would use a diffraction grating, but would prefer something with a built in calibrated scale. What would you guys recommend as far as nm-ish resolution measurement?

You might wanna check out this thread:

http://laserpointerforums.com/f46/killer-deal-usb-spectrometer-update-legitimate-99157.html

And it looks like they're still being sold:

xamayasx on eBay
-
Mini USB Spectrometer Spectromètre Spektrometre - Alluminum Boxe | eBay

 

[Eracoy]

You might wanna check out this thread:

http://laserpointerforums.com/f46/killer-deal-usb-spectrometer-update-legitimate-99157.html

And it looks like they're still being sold:

xamayasx on eBay
-
Mini USB Spectrometer Spectromètre Spektrometre - Alluminum Boxe | eBay

I have read through that thread before, and didn't get a good impression. It seems nice for having it all packaged up, but both the accuracy and precision weren't reliable. I have repeatedly tried to use diffraction gratings for wavelength measurement, but just couldn't get a linear fit like expected. Looking around, there isn't much between $10 diffraction grating based with low enough spread that you can't discern lines and the $xxx or more lab units. It would be nice to get something that could show separate but close together lines.

 

[WizardG]

I have read through that thread before, and didn't get a good impression. It seems nice for having it all packaged up, but both the accuracy and precision weren't reliable. I have repeatedly tried to use diffraction gratings for wavelength measurement, but just couldn't get a linear fit like expected. Looking around, there isn't much between $10 diffraction grating based with low enough spread that you can't discern lines and the $xxx or more lab units. It would be nice to get something that could show separate but close together lines.

Try this: Set up the lasers to be compared such that you have a vertical line of dots on a wall. The goal is to have the beams as parallel as you can get them. Now put the diffraction grating in front of the lasers and find the first, or if possible, second order diffracted dots and compare the angle the beam was directed at by the grating. This won't give you a quantitative measurement of the wavelength but should provide you a clear qualitative indication of which diode has the shortest wavelength. If needed you could place a 0.1 or finer slit in front of the laser(s) to narrow the beam(s) for better resolution.

 

[Eracoy]

Try this: Set up the lasers to be compared such that you have a vertical line of dots on a wall. The goal is to have the beams as parallel as you can get them. Now put the diffraction grating in front of the lasers and find the first, or if possible, second order diffracted dots and compare the angle the beam was directed at by the grating. This won't give you a quantitative measurement of the wavelength but should provide you a clear qualitative indication of which diode has the shortest wavelength. If needed you could place a 0.1 or finer slit in front of the laser(s) to narrow the beam(s) for better resolution.

I have actually tried this! It is a pretty neat method, I agree. I did not take my measurements with the laser through a slit, and I really should do that next time. Here's some pictures of the setup I used to measure the diffraction:

589nm

532nm

405nm

470nm NUBM07E

And finally, the one I was trying to measure:

This is a NUBM07E that I got from Pman (build thread here) and has a much longer wavelength than others of this diode that I have. I ran the beam through a glass diffraction grating (link) from 1m away. My measurements didn't line up with the equation I was using, in that there was a slightly nonlinear relationship between the distance between dots and the wavelength. However, you can see the effect here, comparing the Pman build to one of my other NUBM07Es:

Not to derail the thread too much (hey, people can use this with their shiny new 505's) but I would like to see more of how to properly do this.

 

[paul1598419]

I have read through that thread before, and didn't get a good impression. It seems nice for having it all packaged up, but both the accuracy and precision weren't reliable. I have repeatedly tried to use diffraction gratings for wavelength measurement, but just couldn't get a linear fit like expected. Looking around, there isn't much between $10 diffraction grating based with low enough spread that you can't discern lines and the $xxx or more lab units. It would be nice to get something that could show separate but close together lines.

I have a USB2000 Ocean Optics spectrometer. These are very good, but a bit pricey. You can check eBay for used ones. After you get it you will need to purchase the software to run it. Also a bit pricey. I also had to purchase a laptop with Windows 7 on it as this spectrometer wasn't compatible with anything higher. When it is all said and done, it can be quite an investment.

 

[BillyBob]

Sadly I won't be able to buy any new lasers for quite a while my family and I have to find a new place by the end of June in Sacramento. But, if you guys get a bunch of diodes and have a few that you don't want hit me up.

 

[LtKernelPanic]

Hmm. Been awhile since I've poked around LPF and if these turn out to be 505nm I might have to build my first laser in several years. 505nm is getting oh so close to my personal holy grail of 488nm. (Yes I know they exist but are ungodly expensive)

 

[Atomicrox]

I'm also in for a 505nm diode.

I have read through that thread before, and didn't get a good impression. It seems nice for having it all packaged up, but both the accuracy and precision weren't reliable. I have repeatedly tried to use diffraction gratings for wavelength measurement, but just couldn't get a linear fit like expected. Looking around, there isn't much between $10 diffraction grating based with low enough spread that you can't discern lines and the $xxx or more lab units. It would be nice to get something that could show separate but close together lines.

It's not supposed to be a linear fit at all. Also you'd have more luck with a denser grating (the diffracted dots will be further away and easier to measure).

 

[Eracoy]

I'm also in for a 505nm diode.

It's not supposed to be a linear fit at all. Also you'd have more luck with a denser grating (the diffracted dots will be further away and easier to measure).

I should try a higher line/mm grating, yeah. Also, I was going off of:
slit separation * sin(dot offset angle) = (integer) * wavelength
I ended up with equal spacing between the dots, so it seems a sin(x)=x approximation works for the range of angles I'm measuring. This means that the distance between dots is a linear multiple of wavelength, or so I would expect.

 

[Atomicrox]

The formula is correct but the angles are too big to use the approximation.