Where can I get a 365 nm laser pointer?

[zyxwv99]

I need it for evaluating diamonds for fluorescence. The standard reference wavelengths in the diamond industry are 254 nm and 365 nm. However, 254 nm is only used to determine what kind of diamond it is (type IIb, etc.) while the fluorescence measure that goes on the certificate is based on 365 nm. This is for diamonds that have a fluorescence rating of none/nil/negligible (but where there's still some measurable fluorescence), so I need something powerful. Narrow linewidth would also be appreciated, e.g., no measurable output above 370 nm.

Also, anything in 254 nm.

 

[Cyparagon]

They don't exist. At least not unless you're willing to get something custom made for 5-6 figures.

Get some sort of mercury lamp with a filter. They have a spectral line at exactly 365nm and that is what the certification you mentioned is likely based on. Use the industry standard.

 

[TheDukeAnumber1]

How about that 365nm light you referenced a little while ago, I'm curious as to how much it outputs above 370nm.

@ zyxwv99
- Industry standard and accuracy is definitely the way to go.

 

[mojo_1234]

There're laser diodes in the UV range available (e.g 375nm) but very $$$$.

Thorlabs - UV Laser Diode: 375 nm Center Wavelength

And what about UV LEDs? There're available for 365nm and even less.

-mo-

 

[norbyx]

I think that a led would be more than adequate to make that job. I don't see the advantage of a laser.

 

[Cyparagon]

How about that 365nm light you referenced a little while ago, I'm curious as to how much it outputs above 370nm.

About half of it.

 

[cev1]

Wouldn't shine a "powerful" anything laser into a cut diamond without some eyewear.

OP is confusing power with intensity. Lasers have extreme intensity (power per solid angle) but very low power. Fluorescence is a linear process, and therefore depends only on the power delivered to your rock (at least up to some saturation limit). You'll deliver a lot more power with a filtered lamp or an LED.

Thor's markup is pretty steep - $2300 is the price from Nichia, I think.

 

[zyxwv99]

Thanks for all the feedback. Just doing a little more research, it looks as if 365nm laser diodes do exist, but only in the research lab. No indication of any in commercial production. The ones at 355 and 375 seem to cost thousands regardless of how few mW they produce.

As for the industry standard, that's really what I'm trying to get away from. Right now the diamond industry is doing the same thing as the banking and mortgage industries before the recent financial meltdown. In 2005 the GIA (Gemological Institute of America) stopped filtering the UV from their grading lamps. Within a year all other major grading labs followed suit. The result is that 1/3 of all diamonds are now over-graded by up to 4 letter grades. That means the diamonds are overvalued by about 40%.

On the other side of the coin, there's a worldwide movement to try to do something about it. Before 2005 fluorescence didn't matter much, since it had little effect on price, so no one paid attention to it. Since then people have taken a closer look at how diamond fluorescence is measured and found that the industry standard leaves much to be desired. They use 9v fluorescent tubes with moderately-priced and inadequate filters. Independent studies have shown that even diamonds with moderate fluorescence are being graded as "faint," "negligible," or "none."

The laser idea is just an experiment. For example, a 1 mW or even 0.1 mW 365nm laser with a good bandpass filter might allow me to see, and perhaps measure, fluorescence that's slipping past the grading labs.

When I said I needed something powerful, I what I meant was just a lot of uv photons striking the diamond. For that I would like a laser. However, the laser itself could be extremely weak as far as lasers go, and still be "powerful" as far as the diamond is concerned. The main thing is a narrow beam so as not to illuminate the surroundings, and a narrow bandwidth.

 

[firelaser]

well im sure you could get one of the lab ones,, if you had a diamond as big as in your avatar lol

 

[zyxwv99]

Actually I do.

It's an 8-point G VS2 with very good cut, polish, and symmetry, and no fluorescence. Diameter: 2.79 mm. Depth: 1.69 mm.

Price: $38.88.

In the world of diamonds, photography and lighting are key.

 

[firelaser]

Actually I do.

It's an 8-point G VS2 with very good cut, polish, and symmetry, and no fluorescence. Diameter: 2.79 mm. Depth: 1.69 mm.

Price: $38.88.

In the world of diamonds, photography and lighting are key.

true but i was meaning if it was as big as it was on my screen, which would make the actual diamond, about 3 inches wide..lol

 

[cev1]

A laser is certainly not your best light source for your application. They are expensive (even if your color was obtainable), low power, and highly non-uniform. The uniformity is especially important if you are trying to make a "standard" for grading something like a diamond. Speckle induced by multiple bounces of coherent laser light from a diamond can introduce tons of noise to this sort of measurement.

There are any number of industrial UV sources producing watts of output at 365nm. That is what you want.

You mentioned saving money on filters already, so I'm not preaching to the uninitiated when I bring them up. If you want no light above 370 nm, get a high-end dichroic or band-pass filter. Look at Semrock and you will find something in the $250-$600 range. You can also get the filter for putting in front of your sensor to measure the fluorescence.

 

[zyxwv99]

Thanks for the feedback. You've convinced me. The clincher was the light bouncing around inside the diamond and reflecting off its facets. I've seen what an ordinary laser pointer does, and it's not what I need. Diffuse light is definitely the way to go.

Even binned diodes are notorious for wavelength variability. Plus the wavelength goes up as they get warm. Until now I'd been looking at Newport filters, but Semrock looks like a good resource too.

As for a diamond the size of my Avatar, on my screen it appears to be about two inches in diameter or about 50mm. That would make it 450 carats, or halfway between the Cullinan I and the Cullinan II. Once you get above a certain size, they all run about a million dollars a carat or higher.

 

[Cyparagon]

diamonds are overvalued by about 40%.

I would argue it's a lot more than 40%.