Confused about night club laser shows

[rx7sr4]

Hey

In night clubs and stuff they have those big laser show systems and there 160mw. How come these don't blind anyone? is there some sort of filter in them? thats what i want with my blu-ray laser so i don't potentially blind myself accidently. I just want a bright laser.

 

[lemonwonder]

You want a bright laser.. But want a filter to make it dim enough not to blind you.. Right

Theres fog in night clubs and the beams would be very wide I guess. I know Karbon (or someone else) is a DJ so he could fill us in

 

[HIMNL9]

Also, laser shows scans at really high speed (ok, the good ones, after all )

So, also if you become hit in an eye, is usually for 1 mS or less, the effect of 160mW for 1 mS is like a flash for photography, can you set to see a dark spot for a while, but is not permanent

 

[Deleted member 8382]

usually, at least here in spain, the scanners that hit the people are 5mW greens.
Also, high power scanners that hit the people are on the Khz range, and they scan a very big area in every scan, so the power that goes on your eye after all is really slow.

 

[ElektroFreak]

Another reason is that many times if a scanner will be used for crowd-scanning, the divergence is increased so that by the time the beam reaches a retina the power density is too low to cause damage.

 

[rkcstr]

Well, sounds like you're not quite sure what is going on with why lasers can harm your eye.

How bright a laser is (simply) based on how much power it puts out and how sensitive your eye is to the wavelength of light it emits. You can't "filter" out the ability to harm your eye with a single wavelength of light without decreasing power.

HOWEVER, what you are probably thinking about are DPSS systems, which use an infrared wavelength of light to pump crystals which then emit another wavelength (like 532nm-green, or 473nm-blue, etc), but also don't emit/pass a pure wavelength and can still have some infrared mixed in, which you can't see (not very well, anyway). The power of that infrared light can be as powerful or even more powerful (potentially much more) than the visible wavelengths. In that case, you could filter the infrared and not (significantly) decrease the power of your desired wavelength. But, that still doesn't make it "safe". Depending on the power output of the visible wavelength and other factors like the scanning speed and divergence, like mentioned, it can still injure your eye with exposure.

Now, with Blu-ray lasers or other diode lasers (ie directly emitted by the diode), the light is of one wavelength (well, mostly), so there is nothing that can be filtered to prevent eye damage unless you actually decrease the overall power output of the laser, which is what protective eyewear does.

So, if you want to make your laser "eye safe", get some protective goggles or don't turn it on And, don't forget that goggles only make YOU safe, not others (unless they have goggles too).

 

[chipdouglas]

this is a question. i have read that crowd scanning is safe also because of the distance from the scanner to the crowd. now ignore the scan/galvo speed and work with me on the distance thing. if a laser can go over a mile, is 50 feet really gonna minimize the damage a laser can cause?

 

[rkcstr]

Well, given the same scanning speed (degrees per second), a farther projected beam would mean that as the beam travels it is covering more distance with time than if it was projected closer.

 

[KGB_Productions]

Scanning Audiences at Laser Shows: Theory, Practice and a Proposal

Here is everything you ever wanted to know about Crowd Scanning at shows safely. Enjoy

Scanning Audiences at Laser Shows: Theory, Practice and a Proposal
http://www.laserist.org/files/audience-scanning_overview_2pt1.pdf

Check this out also:
PASS: Professional Audience Safety System
http://www.pangolin.com/PASS/index.htm

 

[andy_con]

also 160mw is so not powerful LOL

 

[ElektroFreak]

^Thanks for those links KGB.. I wasn't necessarily looking for that info, but it's invaluable nonetheless. I'm glad I ran into that post.

 

[marks47]

I've been in maybe one or two clubs that had lasers... But don't they *HAVE* to mount the mirrors X number of feet in the air? They should be visible through the fog, and nobody should be able to "look down the beam" via mirror, or head-on... ?

 

[KGB_Productions]

Its 9ft above the crowd and you *could* look down the beam if the show had the beams pointed towards you. Scanning isn't Illegal, Just puts the producer/promoter in a situation if anything were to happen. It still happens here in the USA.

 

[Cenobite9]

The club I go to has two laser shows mounted on each end of the club. I've learned not to sit at the bar since one the lasers will hit you directly in the face from time to time. It's annoying but doesn't seem dangerous.

 

[nikokapo]

What he needs to know is that crowd scanning is fast enough for the beams to sit on anyone's eyes. This means that it's so fast it can't burn anything. Also, there are lots of standards that have to be met to put on a laser show which also involve the height the laser modules are, etc.

 

[andy_con]

a night club near me has a 5watt gas white light. they crowd scan all the time.

5watt is a litle powerful for night club crowd scanning.