Blue Ray CNI 50mw beam width at aperture?

[davidgdg]

Tested out my new 50mw BR from CNI. Bit worried it may be a dud. Would welcome advice. Beam width at aperture is 4mmx6mm which is way larger than my greenies (not just oval but the top quarter of the beam seems to be cut-off). Spot visibility in darkness is only about 200metres, much less than the specified 1 to 2 km. The spot is way less visible than my 1mw greeny. I know the violets are much less visible mw for mw, but I was expecting a bit better.

Haven't tested divergence yet, but am worried there may be an optics/focusing issue. Is 4 to 6mm beam width at aperture normal for these lasers? I am used to nice tight beams and this came as a bit of shock. Would I only expect 200metres spot visiblity for a 50mw violet? If so, how do CNI get the 1 to 2km figure?

Thanks ....

David

 

[daguin]

Tested out my new 50mw BR from CNI. Bit worried it may be a dud. Would welcome advice. Beam width at aperture is 4mmx6mm which is way larger than my greenies (not just oval but the top quarter of the beam seems to be cut-off). Spot visibility in darkness is only about 200metres, much less than the specified 1 to 2 km. The spot is way less visible than my 1mw greeny. I know the violets are much less visible mw for mw, but I was expecting a bit better.
Haven't tested divergence yet, but am worried there may be an optics/focusing issue. Is 4 to 6mm beam width at aperture normal for these lasers? I am used to nice tight beams and this came as a bit of shock. Would I only expect 200metres spot visiblity for a 50mw violet? If so, how do CNI get the 1 to 2km figure?
Thanks ....
David

First, have you read this?
http://www.laserpointerforums.com/forums/YaBB.pl?board=b_blurays

Second, without a laser power meter there is no way to tell what the output is. If you want someone with an LPM to test it for you, I and several other members of the forum will test it for free. You will just have to pay the shipping (unless you can find someone nearby you.

Third, these distance estimates are pure bunk. I'd be willing to bet that if you stand 2KM away from the laser and it is effectively shined at you, on a crystal clear night, without a moon, you would be able to "see" the violet light. That is how silly the range/distance numbers are.

Fourth, the beam is "fatter" than the green AND the info about scatter and the eye's inability to focus effectively on the light (covered in the link above) will make it appear even fatter.

Peace,
dave

 

[davidgdg]

Thanks Dave

Yes I read that first. I can vouch for the weird halo effects when the spot and beam are viewed. Quite hallucinogenic.

I'm getting a Laserbee so will check power then. But I'm assuming in their favour that CNI's figure is right.

I'm sure if I were looking in-beam I would see it from a long way away! I did some calculations a while back for in-beam visibility for my 125mw green and came up with a figure of about 8 thousand miles if I were in space and the beam were shining up at me! But of course in-beam viewing is a different question from the visibility of the spot. Even a 125 mw spot wouldn't be visible more than a few miles away from the user. And the visibility figures quoted are of course of the spot as viewed from the user's position, not the beam as viewed from end-on!

Yes i've noted the apparent fatness of the beam viewed in-air. I think that is part of the optical effect from the eye's inability to focus the violet. I don't have any problem with that.

My concern is the beam width at apperture which is not an artifact but was measured with a ruler wearing red goggles. It just seems very large compared to all my other lasers (misc greens and a  pulsar) and that, plus the dimness of the spot at any sort of range in darkness, make me suspect there is an optics/collimation issue going on.

If you have a BR, can you do me a favour and measure the beam width at aperture and let me know the figure?

Cheers

David

 

[GooeyGus]

did you order this directly from CNI or did you get it from someone else who said it was from CNI?

 

[davidgdg]

did you order this directly from CNI or did you get it from someone else who said it was from CNI?

The latter.

I have since spoken with the retailer who says that nobody measures beam width at the aperture and that the focus spot is 1 metre from the aperture. I'm getting the pointer back tomorrow so I'll do some measurements and report back.

 

[GooeyGus]

How much was it? Not trying to pry... but this could be important.

I have a feeling that this may not be a real CNI pointer. It could be a regular blu-ray built inside of the CNI host.

The REAL CNI laser has like a 2mm beam at the aperture, and yes manufacturers DO measure at the aperture. If the beam is focused to infinity, there should be no 'focal point' to the beam. It shouldn't focus to a point and then diverge. CNI sets all their lasers as close to infinity as they can get.

 

[HumanSymphony]

How much was it? Not trying to pry... but this could be important.

I have a feeling that this may not be a real CNI pointer. It could be a regular blu-ray built inside of the CNI host.

The REAL CNI laser has like a 2mm beam at the aperture, and yes manufacturers DO measure at the aperture. If the beam is focused to infinity, there should be no 'focal point' to the beam. It shouldn't focus to a point and then diverge. CNI sets all their lasers as close to infinity as they can get.

Truth. The CNI 405nm laser is supposed to have great beam specs. That's part of the reason it costs so much cuz they invested lots of time and money to make it that way ;D

 

[davidgdg]

Thanks to all who have replied. The laser was equivalent to US$ 300. It is in a CNI case. I have done some measurements as best I can:

Beam width
At aperture now seems to be ~ 1.5mm x ~ 4.5mm (better than my previous measurement)
At 1 metre ~ 3mm x ~ 3.5mm
At 2.5 metres 1mm x1mm
At 6.7 metres ~6mm (max) x ~6mm (max) with a strange crescent shape

Based on the above it seems to be focusing at ~ 2.5 metres and then diverging thereafter at about 1mrad. I guess this isn't too bad, though the divergence is above the CNI spec for this model.

 

[GooeyGus]

Can you take the golden aperture cap off and snap a picture of what is underneath? This will be the deciding factor. If we see an aixiz lens, we know it's a hack job. If it's not aixiz and looks ot be custom optics, it's CNI.