# I just saw a RED laser beam at day time



## cdesigns (Sep 13, 2007)

Ofcourse I was watching CSI: Miami and the used a RED laser "Pointer Style" to follow a bullet trajectory and the beam was very visible. I'm 100% sure it was computer generated but is there such red laser portable that the beam can be seen during day light??


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## chuck (Sep 14, 2007)

Of course...but the lower visibility of the red light, means that a visible beam requires a much higher mw rating. Anything common in the US, ie 5mw or less, won't be visible unless you have a major amount of smoke, smog, pollution, or dust in the air.

-- Chuck Knight


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## allthatwhichis (Sep 14, 2007)

I'm sure a half watt or so should be visible, maybe less depending on what wavelength. I'd say a watt at 671 or 660, but I think a 500mW 635 you'd see. I'll fire my 200mW maxyzmodule out the window (terminating on my back yard privacy fence...) when I get home from work and see if I can see it.


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## chesterqw (Sep 16, 2007)

1W should be good


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## ixfd64 (Sep 16, 2007)

I've heard that green lasers need well over 300 mW in order to have a visible beam in sunlight, so I'd imagine that a red laser would need several Watts in order to do the same.


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## AJ_Dual (Sep 18, 2007)

Also keep in mind that the camera could have been on a low-light setting, (CCD sensitivity, the iris, or both) overexposing the shot, and that the actual "daylight" or the sky would have looked quite dim to our eyes were we actually there, so the beam wouldn't have been competing with full-blown daylight after all, and of course the camera would be much more sensitive to the beam as well.

Also, red is at one end of the bell-curve for human vision sensitivity, but camera film and CCD's don't have that limitation also enhancing the laser's visibility.


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## nero_design (Sep 24, 2007)

I've seen a green 120mW beam in sunlight although the laser was pointed away from me and I was very close to the beam itself (looking down the shaft of the unit almost).

As for Reds, no.... CSI is FULL of amazing falsities. From DNA scans which should take three months even if there's no backlog (on the show it happens within a matter of minutes or hours) to impossible software (often they use Adobe Photoshop and add sound effects whilst tracking into and out of an image). Your biggest clue to the Hollywood Cometicism of CSI is the fact that they all walk around without a MASK, HAZMAT SUIT and booties and gloves on plus a hair cover whilst entering crime scenes to obtain and gather evidence. You simply can't do CSI work with your body and clothing exposed like that for scene contamination potential. A decision was made by the producers to reveal the faces of the actors and then a further decision was made to allow them to wear their "identifying clothing" in place of a hazmat suit. Real life CSI work is by no means even similar to the show on television... which is your first hint that they have to fake the lasers.

The red lasers used indoors on CSI are 5mW red pointers which can screw onto dowling rods to approximate the trajectory of a projectile. And we all know that a 5mW is invisible to the eye (beamwise) unless it's almost completely dark and fog is used. They usually fog up the set and shoot the lasers close to the beam source at the correct angle and then DIGITALLY enhance the beam. This is done on the "Compositor's" computer (the guy who makes the final digital layer pass edits) and can be done by isolating the color (red) and telling the program in the compositor's suite to enhance all red within a specific area. But on some of those episodes, I have seen a fake beam added since a real one would not have showed. Other times the few cuts showing the lasers show a LOT of heavy mist in the room due to a fogger. No 5mW laser would ever have a visible beam in sunlight even with a fogged room. You MIGHT get lucky if you shone the same laser over steam emanating from a hot cup of coffee but again, not in direct sunlight.

It's sadly the nature of the industry to fake the reality (or enhance it) to give a better visual for the audience.

All lasers require particles in the air for the beam to be visible. So a red laser would need to be in the order of at LEAST 5-10 Watts to show any visible beam in daylight PLUS you'll need to have a dark area on the other side of the beam to allow your eyes to isolate the beam against the background.

/works as a Visual Effects artist for film and television


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## allthatwhichis (Sep 26, 2007)

Yea, I could not see my 200mW red, even in the shade... :candle:


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