First of all, let me just say that I’m not one of those people who are going to be pointing it at airplanes or screwing around in a movie theater, this is just going to be for pretend lightsaber battles, pointing at things in the dark, and annoying cats.
I want a powerful but small laser pointer. The ones I’ve bought off the shelves somewhere usually break pretty quickly, or they are so weak that I can’t even see the dot if I’m pointing at a house across the street in the dark.
I read somewhere that the brighter, more powerful ones are not red but green. Looking on Amazon, there are some violet ones as well.
It also gives me stats like its 5 mw, and 500 nm but I have no idea what those stand for and if they are good or not. What should I look for in a powerful laser pointer?
Check out wickedlasers wickedlasers.com. They have a nice 1.25 watt blue one for $399. I guarentee you’ll be able to see it on the house across the street, at noon!
Green is the most visible.
I have a 20mW green laser I got off of ebay of $20 that is plenty bright enough for anything I want to do, with risking permanent eye damage.
FYI, a pointer over 5mW is not legal in the US. They sometimes get around it by selling kits or parts that the owner has to assemble.
As pointed out, green will have the highest apparent brightness for a given power among commonly available colors. If you want a red one, make sure it is a 632nm, not a 650 or 670.
I was playing with a buddy’s 1 watt red pointer and it scared the crap out of me. You could easily write with it on a dark plastic surface. I can only imagine what it would do to a retina.
Anything more powerful than 5 mW risks permanent eye damage. 5 mW is the limit at which the blink reflex is fast enough to protect you.
A green laser of a given power will appear the brightest, because your eye is most sensitive to green light. You can see the beam from a 5 mW green laser in the dark.
They have 5 mW blue pointers now, as well as violet pointers. Both of these are more dangerous because the blue light is higher energy and can cause delayed photochemical to your eye. This is not very well-studied, the long-term effects are unknown, and I would not take the risk.
I would certainly not use anything but a red or green 5 mW laser around a pet.
A 1.25 W laser of any color is ridiculously dangerous. If you pointed that thing anywhere near me or my house I’d literally treat it as if you had fired a gun at me. Forget about not pointing it in your eye, just looking at the spot on the wall without safety goggles is enough to cause instant retinal damage.
For the uses you are proposing, a 5mW green (532nm) laser will be more than sufficient. I have one that labeled 5mW, though I swear it’s more. It’s bright! Easily can see the beam path in the dark as it reflects off dust in the air. Great for astronomy, pointing out stars and such (just watch out for the airplanes). However, it would be way too bright to use as an actual laser “pointer” as in a classroom presentation or such. It would have the audience squinting at the board.
So, yeah, 5mW 532 nm is perfectly suited to teasing the cat and light saber battles!
mW is milliwatts. It is a measure of how much energy the beam puts out per unit time. 1 watt is 1,000 milliwatts.
Note that this is not directly comparable to light bulb ratings, which are often expressed in watts. A laser pointer is rated by how much light energy it emits, a light bulb is measured by how much electrical energy it consumes (e.g. a 60W bulb). Generally only a small fraction of the electrical energy consumed by a normal bulb is emitted as light.
nm is nanometers. It is the wavelength of the light emitted (lasers emit only a single wavelength, whereas normal “white” light bulbs emit a whole range of wavelengths). Wavelength is the same thing as color.
It actually depends. Your eyes’ sensitivity to different colors changes depending on the ambient light level. In daylight, the ranking will be violet, blue, red, green, where green is the brightest. In daylight there is not much difference in perceived brightness between red and green, but violet and blue will appear significantly dimmer.
In dark conditions, it will be red, violet, blue, then green, with red being approximately as bright as violet, blue being noticeably brighter than violet, and green brightest of all.
Essentially, in daylight reddish light is more visible than blueish light, but in darkness it is the opposite. This is plotted and explained on Wikipedia.
That’s not true at all. It’s bright enough to cause an afterimage, but permanent damage? No. (unless the wall is an actual mirror and your eye happens to be at the reflection point)
This is not correct. You should not spread misinformation on safety-critical topics you know nothing about.
A class 4 laser is any laser with a continuous output power greater than 500 mW. 1.25 W is more than twice this threshold. The principal difference between a class 3B and class 4 laser is that the diffuse reflections (e.g. on a matte wall) of a class 4 laser are hazardous to your eye, while those of a class 3B are usually not. You can find cites for this all over the place.
None of those say anything about causing instant retinal damage. And 2.5x a “not harmful” level certainly does not mean “instant harm” for a situation like this. The are just arbitrary thresholds and there’s nothing magic about that level. Not to mention that, like any safety rating, there are generous margins built in.
We’re talking about mid-wavelength light here, so there’s no concern about UV damage or the like. Retinal heating is the damage mechanism. That 1.25 W of light is compressed to, say, a 1 mm spot (that’s probably generous–most lasers I’ve seen don’t do nearly this well). That’s a brightness of about 1.6e6 W/m^2. The Sun’s surface is 6.32e7 W/m^2. Note that surface brightness is independent of distance–distance only affects the size of the projected image.
So the Sun is way brighter than the puny laser (even taking atmospheric absorption into account) and no one argues that it causes instant damage. Yeah, don’t look at it for very long. But a quick glance? No biggie. Dilated pupils bring the numbers closer but still only by 10x.
In those cites, how do you distinguish between “hazardous because it causes an afterimage and maybe some temporary pain” and “hazardous because it causes permanent damage”?
Maybe not on purpose, but if you’re getting your cats to chase it, there’s a strong chance that at some point you’ll blast them directly in the eyes.
mW = milliwatts, a measure of power output of the laser. one milliwatt is one thousandth of a watt. For reference, UPC scanners at stores are typically a couple of milliwatts.
nm = nanometers, referring to the wavelength of light emitted by the laser. One nanometer is one billionth of a meter. Visible light ranges from about 350 nm (violet light) to about 750 nm (red). Infrared and radio waves have wavelengths longer than red, and ultraviolet/X-ray/Gamma waves have wavelengths shorter than violet.
My current cat loves chasing her red laser pointer (her predecessor couldn’t have cared less). One odd thing: if one shines a laser pointer anywhere near my ringneck dove, she freaks and goes into a wing-flapping panic. Any clue what her malfunction is?
I assumed that the answer to the OP’s question was “killing power.”
My conure freaks out over an ordinary flashlight. He will come off his perch and try to chase the circle of light. This has been useful in the past, because one time he crawled up behind my mother’s dishwasher, and she used the flashlight beam to coax him back out.
