By Evan Ackerman
Well, I’ve had my 250mW Hulk from Dragon Lasers for nearly a month now, and I’m finally feeling guilty enough to write up the review and send her back to Dragon Lasers. Unfortunately, I don’t get to keep this scary piece of hardware, so you’ve got some assurance of objectivity in this review. I tried to be as comprehensive as I could, so the review is pretty long, but there’s a bunch of pictures as well as some video with stuff on fire at the end. So, read on!
First, the specs: I’ve been testing a 250mW Hulk model from Dragon Lasers, which operates at 532 nanometers (green). It’s hard to really describe what 250mW means, but as far as lasers go, it’s most likely exponentially more powerful than any laser you’ve ever used. Later in this review, I’ll try and illustrate how powerful it is. The unit itself is fairly beefy: without batteries, it weighs in at 225 grams and is 210mm long… In fact, if you imagine yourself holding a lightsaber, I’d say it’s about the same size. Like a lightsaber, there’s a largeish button to turn the laser on, and also like a lightsaber, the beam comes on instantly. UNlike a lightsaber, the laser has a safety shutter at one end: turning a dial on the tip of the laser perhaps 40 degrees closes an internal metal lid over the beam aperture, rendering the laser safe. And trust me, it’s a useful feature, since the button is alarmingly easy to push and if it gets bumped on in your backpack or something it could start a fire in seconds.
Let me digress here for a second to talk about laser safety: this thing is kinda scary to use at times. The backscatter from the beam at a distance will cause the same sort of temporary blind spots that you get from staring directly at a light bulb. At closer range it will cause the same sort of temporary blind spots that you get from staring directly at the sun from the equator at high noon on an equinox (just about). And that’s when it’s pointed away from you. At full power (more on that later), accidental reflections into your eyes is a substantial concern, and as for pointing it directly into your eyes… Well… I treated it a bit like a loaded gun: do not point at anything you are not intending to destroy (or at least blind). In other words, this is not something for you to amuse your cat with. I wore sunglasses when pointing it at something at close range, but realistically you just need to be a bit careful and use common sense.
Anyway, just a few more specs: The lifetime of the laser diode is over 5000 hours, which is a heck of a lot… That’s over a year and a half of 8 hours a day 5 days a week continuous on time, if I did my math correctly. And you CAN keep it on continuously: the front third of the laser is a heat sink, which gets warm (but not hot) after lengthy use. So, how long can you use it for? The good news (excellent news) is that it runs on two standard C batteries, which cost around $1 each. These batteries will run the laser at full strength for something like 5-10 minutes, and then at reduced strength for a lot longer (I haven’t been able to run it down completely, since I’ve been swapping batteries to keep burning stuff). In a way, this is a feature, since after the peak power runs down, you can actually use the laser without nearly as much risk of damage to yourself, your stuff, or your pets.
Now, on to the fun part. The beam itself is a vivid bright green. It’s visible indoors during the day if you look closely, and under indirect sunlight, and crazy bright in the dark. It’s almost too powerful to use as a flashlight at night, since it’s hard to look directly at the beam spot, but if you point it somewhere near you, the backscatter with light up everything around you, no problem. According to the specs, the beam will travel about 100 miles, which is of course impossible for me to verify, but it’s safe to assume that if something is visible to you, this laser can hit it. Shining it up into the sky (which I did in a rural area while using one of these) is a bit anticlimactic, because you have no sense of how far the beam is going… It looks like it goes on forever. If you turn it on and walk away from it a bit, the beam looks like a fluorescent green fishing line stretching toward the stars. I’ve tried a multitude of ways to capture this in pictures or video, and it just doesn’t come across… You really have to see it for yourself. I did get some decent pictures of this laser hitting distant objects, though. Don’t let yourself be fooled by the fact that the beam doesn’t lose brightness or diverge over distance: In both of these pictures, the laser is about 1 foot away from the camera.
That’s the Bay Bridge, which connects Oakland to San Francisco, from a distance of about 2 miles (I took this photo from Pier 33 while I was at dorkbot). The beam spot is clearly visible on the base of the bridge. I was going to shoot for Alcatraz and the Golden Gate next, until one of the dorkbot guys mentioned that the Navy gunboats patrolling the bay probably would not appreciate that. I was nervous using this in an urban area anyway… It’s so powerful and visible that I was scared of being arrested on some Homeland Security pretext or something.
That’s the Transamerica building in downtown San Francisco, from a causeway out into the bay. The exposure length is several seconds, and I would like to point out a very faint arc just to the left of the building and beam. This was caused by a seagull, which freaked out, attacked the beam, and then flew away squawking.
I think the most interesting part about this laser are the surprising results that you get when you just start playing around with it. This next picture was a total accident: I happened to shine the Hulk through a half-empty bottle of water with condensation on the inside, and this was the result, projected on a wall across my apartment:
Don’t ask me how or why that works (something to do with refraction through the condensation droplets in the bottle?), but it does, and it’s awesome. Moving the laser even slightly creates an entirely new pattern (as you’ll see in the video at the end); here’s a long exposure with some movement:
Lasers, being beams of light, are lots of fun if you’ve got some mirrors handy. I managed to get the beam to bounce back and forth eight (I think) times between two parallel mirrors:
This long exposure is a little more complicated: I’m standing just left of camera, shining the laser at the mirror left of center, which is reflecting the beam at the mirror on the right, which is reflecting it again into the trees at the far left. The beam divergence is due to my shaky hands over the long exposure:
As for burning stuff, lasers are surprisingly picky. They work, as far as I know, by throwing photons at something really really fast (er, densely?), thereby raising its temperature. This means that they won’t efficiently burn things that are reflective or things that distribute heat quickly. They’re also point sources, so although you can make holes in things, you can’t use a laser like a blowtorch (no frying eggs). The reflectivity of something is probably the most important factor as to whether or not you can burn it. You can cause virtually anything dark colored to give off smoke in a second or two, but anything light colored or white is quite a challenge, no matter how flammable it might be. For example, I couldn’t get the laser to do anything at all to a marshmallow until I put a black dot on it with a Sharpie. It would then chew happily through until the black dot was gone, at which point it would stop doing anything. Same thing with a stick of butter. Jello was too transparent. Black trash bags melted easily, white trash bags did not. Matches were no problem, and neither was electrical tape, even from a distance. The trickiest part, really, was keeping the laser centered on your target: the further away you are, the harder it gets. My goal while reviewing this laser was not to just pop a bajillion balloons, but rather to illustrate what this powerful laser can, and can’t, do. But I’ll shut up now and let you enjoy the video, and in self defense, I needed a 6+ minute long soundtrack and I was watching Hackers last night:
The moral of the story? I want to keep it. I can’t say for certain why I want to keep it, because it’s not like I have an everyday use for it (although when I’m walking around with it I feel like I’m armed). It’s certainly good for pointing out stars and such, and if you’re ever lost in the wilderness, it makes a great beacon and firestarter. I love love love the fact that it doesn’t take some kind of specialized battery, and I’m pretty sure that you can get rechargeable C batteries, making the Hulk basically free to operate. The cost? The model I tested is $850; Dragon Lasers offers several tiers of output power if you’re not looking to spend quite that much. Their prices are substantially cheaper than some other places, but the tradeoff is that Dragon Lasers is based on China. I’ve found their customer service to be quite knowledgeable and friendly, though, and they seem like dependable guys. I wouldn’t hesitate to order a laser from them. You won’t regret it.
Oh, and I’ll have the laser for another day or two, so if you have a question or feel like I’ve missed something, post in the comments and I’ll get back to you. [UPDATE- Just to clarify, I was under no illusions that my sunglasses would protect me from the laser beam, because they wouldn't... I only wore them to make it easier to look at the beam spot. Again, this is a potentially dangerous laser, and you need to be careful while using it, especially around reflective surfaces.]
[ Dragon Lasers ]