"5 mW" violet laser pointer from eBay
As promised, here is the review for the 405 nm laser I bought on eBay last month.
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Product: "5 mW" 405 nm laser pointer
Seller: eBay user "demonerrr"
Price: $2.65
Recommended accessories: Safety goggles
Don't knock the "cheap eBay pens" until you've tried them
An amazing thing about technology is how quickly items drop in price once they enter mass production. The 405 nm laser diodes that power Blu-ray drives are such an example. Due to supply and demand, these once-expensive devices are now a dime a dozen.
Violet lasers first appeared on the hobbyist market in late 2006 when Wicked Lasers launched the 20 mW Sonar. Its $2,000 price tag wasn't exactly pocket change. The original Sonar was actually a pulsed laser; the 20 mW figure referred to peak power, and the average output was measured to be one-tenth of that. In other words, the price per mW was almost $1,000 at the time of release!
Yet costs rapidly fell as 405 nm diodes became common. At the same time, their outputs increased as manufacturing processes improved. Prices have dropped to the point that it's now possible to buy a high-powered violet laser for just a few bucks.
I took the plunge and ordered one on eBay after the temptation became too great. The seller was based in China; though the package took a whole 19 days to arrive, long transit times aren't uncommon for overseas items. The shipping was actually pretty fast given that it was free and taking into account that I placed the order during the peak holiday season.
The pointer is similar to those sold in dollar stores. There are no labels or markings indicating its manufacturer, meaning you're likely out of luck if it breaks. The laser uses two AAA batteries; the positive terminals face the opposite direction of the beam. Users should make sure to insert them correctly as the driver may not have reverse polarity protection.
The dot isn't much brighter than that of a normal red laser pointer, but this wasn't unexpected as 405 nm is at the edge of the visible spectrum. On the other hand, an interesting property of 405 nm light is that it causes fluorescence in many materials. You could point the laser at different things (obviously not people or animals) and see the dot change in color.
The laser produces a faint but visible beam in dark environments. It was difficult to get an accurate profile of the beam due to its highly irregular shape. The beam is about 5 mm wide at the aperture and has a divergence of around 1.3 mrad. I'd have preferred a more rounded beam but can't really complain given the price of the laser.
Of note is that laser pointers sold on eBay are often more powerful than the specs suggest. Such lasers are usually advertised as 5 mW to comply with eBay policies. I don't have a laser power meter and cannot measure the actual output, but it's probably somewhere between 15 and 25 mW going by my observations.
While this particular unit can't burn anything or even sting my skin, chances are it's still strong enough to cause eye damage. Users should therefore take eye safety into consideration. Though green laser goggles will block a portion of violet light, I'd definitely recommend a pair of dedicated 405 nm goggles for higher-powered lasers.
Despite their shortcomings, the violet laser pointers from eBay are great entry-level lasers for interested hobbyists. However, be prepared to spend a little more if you want something that can cut and burn.
-- Danny Chia
Final verdict: 75% / Good
Highs: Very attractive price; performs above specifications
Lows: The beam quality could be improved; absolutely no company information
Bottom line: The 405 nm lasers on eBay are an incredibly good deal, but you get what you pay for.
Photos
The package
The wrapped laser
The correct orientation of the batteries
The laser, ready to be attached to a shark
The dot
All of the photos and videos can be viewed at my Flickr account.
Your comments
I'd also appreciate feedback on my review. Please let me know if you think it's too lenient or too harsh.
As promised, here is the review for the 405 nm laser I bought on eBay last month.
----
Product: "5 mW" 405 nm laser pointer
Seller: eBay user "demonerrr"
Price: $2.65
Recommended accessories: Safety goggles
Don't knock the "cheap eBay pens" until you've tried them
An amazing thing about technology is how quickly items drop in price once they enter mass production. The 405 nm laser diodes that power Blu-ray drives are such an example. Due to supply and demand, these once-expensive devices are now a dime a dozen.
Violet lasers first appeared on the hobbyist market in late 2006 when Wicked Lasers launched the 20 mW Sonar. Its $2,000 price tag wasn't exactly pocket change. The original Sonar was actually a pulsed laser; the 20 mW figure referred to peak power, and the average output was measured to be one-tenth of that. In other words, the price per mW was almost $1,000 at the time of release!
Yet costs rapidly fell as 405 nm diodes became common. At the same time, their outputs increased as manufacturing processes improved. Prices have dropped to the point that it's now possible to buy a high-powered violet laser for just a few bucks.
I took the plunge and ordered one on eBay after the temptation became too great. The seller was based in China; though the package took a whole 19 days to arrive, long transit times aren't uncommon for overseas items. The shipping was actually pretty fast given that it was free and taking into account that I placed the order during the peak holiday season.
The pointer is similar to those sold in dollar stores. There are no labels or markings indicating its manufacturer, meaning you're likely out of luck if it breaks. The laser uses two AAA batteries; the positive terminals face the opposite direction of the beam. Users should make sure to insert them correctly as the driver may not have reverse polarity protection.
The dot isn't much brighter than that of a normal red laser pointer, but this wasn't unexpected as 405 nm is at the edge of the visible spectrum. On the other hand, an interesting property of 405 nm light is that it causes fluorescence in many materials. You could point the laser at different things (obviously not people or animals) and see the dot change in color.
The laser produces a faint but visible beam in dark environments. It was difficult to get an accurate profile of the beam due to its highly irregular shape. The beam is about 5 mm wide at the aperture and has a divergence of around 1.3 mrad. I'd have preferred a more rounded beam but can't really complain given the price of the laser.
Of note is that laser pointers sold on eBay are often more powerful than the specs suggest. Such lasers are usually advertised as 5 mW to comply with eBay policies. I don't have a laser power meter and cannot measure the actual output, but it's probably somewhere between 15 and 25 mW going by my observations.
While this particular unit can't burn anything or even sting my skin, chances are it's still strong enough to cause eye damage. Users should therefore take eye safety into consideration. Though green laser goggles will block a portion of violet light, I'd definitely recommend a pair of dedicated 405 nm goggles for higher-powered lasers.
Despite their shortcomings, the violet laser pointers from eBay are great entry-level lasers for interested hobbyists. However, be prepared to spend a little more if you want something that can cut and burn.
-- Danny Chia
Final verdict: 75% / Good
Highs: Very attractive price; performs above specifications
Lows: The beam quality could be improved; absolutely no company information
Bottom line: The 405 nm lasers on eBay are an incredibly good deal, but you get what you pay for.
Photos
The package
The wrapped laser
The correct orientation of the batteries
The laser, ready to be attached to a shark
The dot
All of the photos and videos can be viewed at my Flickr account.
Your comments
I'd also appreciate feedback on my review. Please let me know if you think it's too lenient or too harsh.
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