Waterproof 447nm questions

[Athoz]

Hi,
I just got this laser pointer
Wholesale Product Snapshot Product name is 445nm/447nm/450nm 1000mw/1Watt Waterproof focusable blue purple laser pointers burning star pointer torch +free shipping
and I have some concerns and questions post here.
After testing it underwater it seemed to work but it doesn't seem to be fully waterproof from just the two rubber bands between the head and the bottom caps, in lower depths.
The beam is not visible in the morning and during night it is visible under low light conditions. It can burn matches, black tapes and cupboard at the focusing point.
My concerns are:
Based on brightness it doesn't seem to be 1watt as advertised concerning that it is 447nm (closer to center of visible wavelengths).
When I remove the focusing head it doesn't emit a laser straight focused beam but rather something that seems like black light LED.
Is this because a de-focusing lens is used right after the exiting lens of the laser, in order to increase the diameter of the beam so it has lower distortion from the low quality focusing lens?
Do other blue lasers have this wide angle beam?

In the photos below are shown some images of the device and the beam shapes with an without the focusing head, as also that the light is more sensitive to fluorescent surfaces like the light yellow torch.

Sorry for my noob questions,
Cheers!:thanks:

Without focusing head

with head

 

[Encap]

Would guess you are right about output power ---the guys shop show a lot of off the wall misinformation about output powers 3000mw 445nm, several 5000 mw445, even 10W and 30W 445 and 2000mw greens ----obviously not true/bogus specs. A lot of Chinese web stores add extra 0s to output power.
see: Online Store 932670 - Small Orders Online Store, Hot Selling green laser pointers,blue laser pointer,Blue Laser Pointer and more on Aliexpress.com

Maybe it is a 100mw 405nm like this one he sells and says is a 1000mw ---no real way to tell without testing wavelength and output. Aliexpress.com : Buy 405nm 1000mw/1Watt Waterproof focusable blue purple laser pointers burning star pointer torch +free shipping from Reliable 1000mw blue laser pointer suppliers on Online Store 932670

 

[Athoz]

Any wild guess about the beam spread without the focusing head?

 

[Encap]

Any wild guess about the beam spread without the focusing head?

What do yu want to know about it---looks typical of an unfocused diode laser?

445nm usually is rectangular rather than round dot .

Other than that for $45 delivered, you got a laser that works and has o-rings to make it water resistant --nothing more can be determined without testing it.

 

[ARG]

The only way to know the output power is with an LPM, guessing from the brightness of the laser is hardly accurate, but you are probably right in assuming it's under spec.

Some waterproof lasers I've had are hardly waterproof, I wouldn't be putting it underwater.
Most are just water resistant.

P.S. You may want to resize the images, it makes it hard for other people to view.

 

[Athoz]

looks typical of an unfocused diode laser?

This is what i wanted to hear, that there are unfocused blue lasers.
I am going to test it in the lab to check the actual power output and report.
Cheers!

 

[Athoz]

Returned with news.
I went to the lab and checked the values.

At 450nm

I got almost 100mW

Moving up and down in wavelength I found the center at 362nm. This responds to the bandgap of a GaN semiconductor.

at 130mW.

After some talking with some friends there we concluded this is one of the "new" very bright UV LEDs (typical at 100mW) on the market which explain the very wide wavelength spectrum compared to a laser. I think I got my answers.
Thank you for your suggestions!

 

[Encap]

Nice test images. IS great you were able to test it and let us know your findings!

Not a bad deal for $45 delivered even if 1000mw ww 445nm was claimed.

 

[ZRaffleticket]

Wait 362nm...?

 

[Athoz]

I haven't put any time to investigate more on the subject but the peak was at 362 nm.
http://www.sheffield.ac.uk/eee/research/smd/research/uvled

...as the bandgap of GaN is around 360nm...

I think this is an Si doped GaN semiconductor in order to increase the bandgap.

 

[Encap]

Wait 362nm...?

THe article is about LED not laser diodes.

I doubt the peak of 362nm also --405nm rarely go that low even at fringe/edge of multi-mode output.

Would be very difficult to see output, if at all. Typical human eye will respond to wavelengths from about 390 to 700 nm and 362 would not look blue. Humans are generally blind to ultraviolet (UV) wavelengths, due to the high absorption of wavelengths below 400 nm by the ocular media preceding the retina

The other thing is price- UV diode laser, not sold as visible, at 375nm is a few thousand dollars: Thorlabs - UV Laser Diode: 375 nm Center Wavelength

Because of the price of the diode has to be a common mass produced low cost 405nm diode that is not more than a few dollars.

 

[ZRaffleticket]

Ahhh I was wondering-- <400nm is a very odd sight

 

[Athoz]

This cannot be a laser diode. It has a very wide frequency spectrum (wavelength spectrum). As measured at 100mW at 450nm and 130mW at 362nm (assuming the measurements where done correct). Having a blue color means that a substantial amount of energy is around 450-490nm. With the eye it seems much more violet than the images above.