Review of the 405nm 5mW Violet Purple Blue Beam Laser Pen

The 405nm 5mW Violet Purple Blue Beam Laser Pen is a violet-emitting, directly-injected laser. That is, it produces violet laser radiation directly, without the need for messy, fragile nonlinear crystals like those green laser pointers and the amberish-yellow and blue ones as well. It uses two AAA cells -- the same power source used in most other "pen-style" laser pointers and laser modules.

It is advertised to output 5mW of laser radiation at ~405nm.
It actually measures 57.30mW at exactly 405.0nm!!!

It comes in a handsome brass body with a black finish and chrome colored bezel, tailcap, and pocket clip.



SIZE



To get the laser to turn on, first be certain that there are a pair of AAA cells installed. If there isn't, then install them (see directly below), and THEN you can go irradiate something.

Aim the laser well-away from your face first. Press & hold down the button on the barrel for as long as you want or need the laser spot, and release pressure on the button to turn the laser back off.





To change the batteries in this violet laser , unscrew the laser near the center, and set the front half aside.

Tip the two used AAA cells out of the barrel and into your hand, and dispose of, recycle, or recharge them as you see fit.

Insert two new AAA cells into the barrel, flat-end (-) negative first. This is the opposite of how batteries are installed in most flashlights, so please pay attention to polarity here.

Screw the front portion of the tube back on, and be done with it.


Unable to measure current use due to how this laser was constructed.




This is a self-contained laser , and not a flashlight meant to be carried around, thrashed, trashed, and abused - so I won't try to ruin it like I might try to wreck a flashlight in the name of science.

This is a directly-injected laser though, who's active components are the inverter circuit, the laser diode, and the collimating lens. So it should withstand accidents better than a DPSS (diode pumped solid state) laser - the type of laser assembly found in yellow (593.5nm), green (532nm) and blue (473nm) laser pointers. These lasers have several additional components (crystals, filters, etc.) in the optical train, and you can knock them out of alignment by doing little more than looking at them the wrong way. And if any of these components are knocked out of whack, you'll no longer get your yellow, green, or blue laser beam.
Though you still do not want to intentionally drop your violet-emitting laser because it's a precision optical instrument.

There is no label on the product, and therefore no CDRH classification shown; eg. it does not read "Class IIIb" as it should. And it ***REALLY*** should, considering its high output power.

This (not having the proper labelling) is rather expected of a product of non-US origin; sometimes known as the "Hoo Phlung Pu" brand.

From somebody who knows their {vulgar slang term for caca; rhymes with "pit"} about lasers, comes this information:

More on 50-60 mW violet lasers:

The spot is not safe to stare into from close distances. At 60 mW,
assuming a perfectly diffuse-reflecting white wall and fully dilated
pupil, the spot is at borderline between Class I and Class II at a little
over 7 feet. This wavelength also has the extra ill effects of blue and
a bit of the ill effects of UV.

Usually a yellowish dye that naturally exists in the lens of the eye
significantly attenuates deep violet wavelengths. However, this is not
completely reliable. You probably do not want to stare at the violet spot
for more than a couple seconds from distances within a couple feet.

If the spot or your eyes keep moving, then things are OK.


Does this evaluation look an awful lot like the one I made for this laser?
Thought you'd say so.
That's because they're functionally, electrically, and physically identical, so I was able to use its web page as a template for this one.


<font color="#ff0000"> TEST NOTES:
Test unit was purchased on Ebay on 10-06-10 (or "06 Oct 2010" if you prefer), and was received at 5:23pm PST on 11-22-10 ("22 Nov 2010").

I have decided to rate this wonderful little laser four stars!!!
The only real reasons that it did not receive five stars is because the claimed power output and the measured power output vary so greatly (claimed at <5mW, measured at 57.30mW), and it isn't even labelled at all -- a rather severe no-no!!!


UPDATE 01-20-11:
I have given this laser to J.R. in Arizona USA (we were roommates at The Juneau Receiving Home from the late-1970s through the early-1980s and I hadn't heard from him until 12-17-10 {or "17 Dec. 2010" if you prefer}), so that dreadful "" icon will be apppended to its listings on this website, denoting the fact that I no longer have it at my disposal for additional comparisons or analyses.




PROS:
Color is very radiant & unusual for a handheld laser
Uses inexpensive and readily available batteries
The price is right!
Color is very radiant an unu...o wait, I said that already!!!




CONS:
Just the usual suspects for laser modules/pointers - nothing that affects rating...actually, there is one little thing: it is advertised as a 5mW laser, but outputs over 23mW of laser radiation.
That's what lopped that last star off.





MANUFACTURER: Unknown
PRODUCT TYPE: Violet-emitting laser
LAMP TYPE: Sony Blu-ray laser diode
No. OF LAMPS: 1
BEAM TYPE: Very narrow spot
SWITCH TYPE: Momentary on/off button on barrel
CASE MATERIAL: Brass
BEZEL: Metal; laser & lens recessed into its end
BATTERY: 1x AAA cell
CURRENT CONSUMPTION: Unknown/unable to measure
WATER- AND URANATION-RESISTANT: Light splatter-resistant at maximum
SUBMERSIBLE: For Christ sakes NO!!!
ACCESSORIES: None
COUNTRY OF MANUFACTURE: China
WARRANTY: Unknown/not stated


PRODUCT RATING:

The_LED_Museum said:

At 60 mW,
assuming a perfectly diffuse-reflecting white wall and fully dilated
pupil, the spot is at borderline between Class I and Class II at a little
over 7 feet.

Click to expand...

Interested in the math you used here...?

-Trevor

twhite828 said:

Interested in the math you used here...?

-Trevor

Click to expand...

Good evening Trevor,

This is from a laser & optics expert on the east coast -- it isn't my math...not no way, not no how as they say...

His name is Don Klipstein, and his website is Don's light, lamp and strobe site!
He has an email address at the bottom of this web page; he might be willing to enlighten you on how he arrived at the values that you see on my higher-powered laser evaluations.

Interesting. Let me recycle a bit of an old post to explain my curiosity.

Say we shine a laser pointer of 60mW at a perfect 90° angle at some sort of (flat) miracle matte surface that disperses the light evenly in all directions. The area of reflection would be a hemisphere whose radius is the observer's distance from the dot. The formula would be (4πr²)/2, or just 2πr².

Say we are observing at night from a distance of 2m. The area of the surface of the hemisphere whose surface touches the observer's eye(s) would be 25.132m². To make this number more manageable, let's turn it into cm². This yields 251,327cm². The intensity of the dispersed laser light would be 60/251327 mW/cm², or 0.0002387mW/cm². 238.7 nanowatts per square centimeter.

This level of power is well below Class II... even orders of magnitude below Class IIa. :thinking:

-Trevor

BTTT: Added a spectrographic analysis.

12-03-10: Added a spectrographic analysis.

BTTT: Gave this laser to somebody else, so I no longer have it at my disposal for future comparisons or analyses.
I consider this a fairly significant update, so I believe that the "bump" is kosher.