A picture of my (powered on) 450mW high-power green (532nm light wavelength) DPSS laser. Since this picture was taken in the dark, Rayleigh scattering and the effect caused by dust in the beam are extremely pronounced. Although not quite this visible to the naked eye (the camera made the beam brighter due to the long exposure time), the laser beam is still very visible in the dark, even if you can't see where the beam is actually hitting (or where it's coming from, for that matter).
The laser itself is resting on my rather cluttered desk. Visible in the background is my watch, which I was using to time the powered-on time of the laser, which is rated for 100 seconds on then 60 seconds off.
The green laser's pump source is a 2000mW infrared diode (not sure of the wavelength), and the lasing mediums are Nd:YVO4 (neodymium-doped yttrium orthovanadate) and LBO (lithium triborate). The laser is IR-filtered.
For some reason, my camera decided to focus slightly behind the laser, hence why the laser aperture itself is out-of-focus.
Fun fact: By my calculations, the laser is emitting approximately 1.21e18 (1,210,000,000,000,000,000) photons per second.
See also another laser shot of mine, particularly, the same laser, but in the light.
DANGER: The laser shown here is a class 3B laser device. Class 3B lasers areNOT laser pointers, and should never be used for that purpose. Despite the fact that I took the picture with the laser sitting on my desk, and despite the fact that I seem to have fun when using my lasers (I do), I took proper safety precautions to ensure that myself and others do not get injured; for example, I wore ANSI Z87.1-standard green laser safety goggles at all times when the laser was operating.
In other words, unless you know what you're doing, DO NOT TRY THIS AT HOME. You could inadvertently blind yourself or someone else. And, of course, high power laser devices should NEVER be pointed at other people, and lasers of any kind should NEVER be pointed at aircraft, especially those in flight. High-power lasers like this one should be treated with the same respect as you would treat a loaded gun.
Please be aware that high power laser devices may be restricted by laws in your area.
You can download the full resolution version of the image from my website by clicking here, then clicking on the Full Resolution link.