Dealextreme 50mW red is actually a 635nm red laser !!

Lasers are here



The bad news: NOT a 635nm, like many of us thought, but at least hoped. One of the pen has not a perfect alignment, one has a bit dirty lense.

The good news: All in all the pens arrived in good condition. I´m able, other than said before, to send the batteries with them. All lasers have an output between 55-80mW. I randomly put them into the shipping packages.



How do you know that they are no 635nm lasers?
- I´ve watched them next to each other, an other 650nm and a 635nm Atlasnova
- Beamed them along a wall and compared the colors of the overlapping
- Compared beams in the shower (DX 650nm vs Atlasnova 635nm)


Notice
I´ve masked the batterie-laser-contact with a piece of black electrical tape, so that the laser isn´t able to power up during shipping. Make sure to remove it before powering your laser.


When do we get our lasers?
I´m able to ship all of them till Monday. So some of you may get your lasers during the next week. You are allowed to post or PM me when they arrived




I hoped until last that we get some cheap 635nm but in the end we got some nice overspec 650nm for a good price.

Thank you for participating :beer:

Awesome, good deal! Thanks phi for doin this for us!

I am sorry that the pens are the normal 650nm red. I really hoped that you all got the special ones. It is nice to see that these pens are heavily overspec.

Do I see smoke at your lpm ?

sure looks like smoke huh? haha, hey no big deal on my end, I'm glad i spent $20 shipped for a overspec 50mW 650nm pen!

- Compared beams in the shower (DX 650nm vs Atlasnova 635nm)

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Dj you showered with our pens? :tsk: I know you love lasers, but I didn't know you loved them that much!

DJNY said:

All lasers have an output between 55-80mW.

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Thanks a bunch for this great info!
Now I know what power my laser is (well, roughly anyways).:beer:

someone said that you cant know the right wavelength without a spectrometer or the sort. You can (with some error of course, but then again, ur spectrometer also has some error in it).

The easiest way even for those that do not own a difraction grating is by using a ruler (lets say metric) and get it in some angle with the laser. An easy way would be getting the laser parallel to the table and then just getting the ruller one end in the table, other end or halfway or whatever, doesnt matter on some object with a known height and just calculate the angle with which the laser beam is falling onto the ruler. Get the laser to fall onto the scale (you will have black and white spaces spaced by 1mm normally). and see the reflection on a wall or target. Just measure the distance between the 0th order and 1st order maximums and if u know the angle and distance to the target you can calculate the wavelength...repeat several times and with different angles and distances to get a result with less error.

with a diffraction grating from which u know the lines/mm is also easy.


Do not come into here saying theres no way to know the wavelength unless u give it to someone that has a spectrometer...even spectrometers can be miscalibrated! Whilst gratings will always perform great!

The MK I eyeball is perfectly fine for telling the difference between 635 and 650 when the two are side by side. It just sucks as a LPM.

I just made the WL-test through my diffraction grating. Still ~650nm

qumefox said:

The MK I eyeball is perfectly fine for telling the difference between 635 and 650 when the two are side by side. It just sucks as a LPM.

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AHAHAHA! Great answer! But it wont say the exact wavelength Unless u got one of those fancy things Goku and Freeza have

LordKaramazov said:

The easiest way.... is by using a ruler...0th order and 1st order maximums...

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There are a few problems with this.

1. You NEED one, maybe two or three known wavelengths to calibrate the set up. "Atlas nova SAID it was 635" isn't good enough. They vary from diode to diode and they change with temperature, as do all direct injection lasers.

2. Diffraction gratings spread based on angle. The arc lengths is linearly proportional to the angle, but the flat surface of a ruler is NOT. For example, the distance from point p to the X-axis along arc S is not the same as the direct drop from P to the X-axis.

LordKaramazov said:

ur spectrometer also has some error in it

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I've tested it with known gas laser wavelengths and it is accurate to <0.5nm. Try that with a ruler and grating

Cyparagon said:

I've tested it with known gas laser wavelengths and it is accurate to <0.5nm. Try that with a ruler and grating

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I was speaking about a general spectrometer, and not urs or his or whoevers spectrometers.

And what im saying is the simplest way u can know what is the wavelength of a laser by the grating equations, and YES it works for a ruler:



its easy to derive the equation for maximums using the Huygens-Fresnel principle.

And as i said above, it has some error. And if u just leave ur laser stable enough its a rough estimate with an accuracy that id say would go until 90~95%.

Ur spectrometer cant also account for diode instabilities as u said.

and yes, nova saying its 635 wont suffice...they dont test them and they always say +/-10nm.

LordKaramazov said:

Ur spectrometer cant also account for diode instabilities

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What are you talking about? This makes no sense.

I think you missed my point entirely. If you compare one diode laser to another diode laser that is rated for 635, that doesn't mean it is 635. However, if you compare it to a HeNe for example that has a known, constant wavelength for all models and all operating conditions, you'll get a closer result.

LordKaramazov said:

...a rough estimate with an accuracy that id say would go until 90~95%.

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5% tolerance for 635 is 603nm to 667nm, isn't it? I think I could do better with my eyeball-o-meter

Cyparagon said:

What are you talking about? This makes no sense.

I think you missed my point entirely. If you compare one diode laser to another diode laser that is rated for 635, that doesn't mean it is 635. However, if you compare it to a HeNe for example that has a known, constant wavelength for all models and all operating conditions, you'll get a closer result.



5% tolerance for 635 is 603nm to 667nm, isn't it? I think I could do better with my eyeball-o-meter

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Oh i get the diode part...what i was saying is that ur spectrometer cant account for diode instability when it comes to temperature, and "build-up" as it gets stable in one wavelength. but it doesnt make much sense...and yeah, after doin some math (i told those numbers from my head, and i knew i was overrating the accuracy) i can tell the ruler method can go between 99.8% or so to 97.5%...not less than that...and if u repeat with different angles/distances and also measure it several times, most prolly ull hit spot on the wavelength.

yeah 95% is a kinda big interval xD

LordKaramazov said:

spectrometer cant account for diode instability when it comes to temperature, and "build-up" as it gets stable in one wavelength.

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That's why you measure it when it becomes stable. I can think of very few things that are measured when unstable.

Cyparagon said:

There are a few problems with this... They vary from diode to diode and they change with temperature, as do all direct injection lasers.

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Thats the only reason i brought it up...you said it was a problem...its a problem for both the ruler method and ur spectrometer.

If we just measure them when stable, its no problem for any of them :beer: