|
|
Laser Light Show F A Q
This page contains some of the most frequently asked general questions about laser shows that we have received. If you have a question that you feel should be included in this FAQ, please E-mail us.
Q: What are the main kinds of laser effects used in light shows?
A: There are two main classes of laser effects, beam effects and screen effects. In a beam effect, the
laser beam traveling through the air creates the effect. A screen effect is any image or optical effect
that requires a screen or other projection surface to be visible.
Q: What kind of beam effects can I see at laser shows?
A: There are two main types of beam effects, static and dynamic. Static beams are usually turned on
an off and may be bounced from mirrors to create a beam matrix or sculpture in the air. Dynamic
beam effects are moving beams that may include sheets, fans, cones or blades of light moving above
and through the audience.
Q: Why don't I see a lot of beam effects at some shows?
A: Some shows are designed to be graphics and animation intensive and some shows are designed to have lots of beam effects.
Beam effects take more laser power to project so some venues do not use them since their lasers are not powerful enough.
I n other cases the venue does not have the clearances or permits needed for safe projection of beam effects.
Q: When you see laser animations at shows do they just scan the pictures in ?
A: In traditional character animation each picture has to be individually hand drawn (digitised) usually
from artwork prepared by an animator. The images (frames) are then played back in rapid
succession creating the illusion of movement just like a classic Disney movie or Saturday morning cartoon.
Here are some laser frames of a dancing man - you can see the differences from frame to frame (also see
Laser Graphics
Systems).
Example of laser animations frames
Q: Are there other kinds of laser animations?
A: There are sequential frame animations [sometimes called character animation which is discussed
above] and object animation. In sequential frame animation, a sequence of slightly different frames is
projected giving the illusion of a character moving just like in a cartoon.
In object animation, the images on the screen are created by the computer moving or rotating an object.
An example would be a company logo spinning around. The computer can add
perspective or perform line removal to give the illusion that
the 2D image projected onto the screen is a 3D object.
Q: What is the most powerful laser used in laser shows?
A: For lightshow applications, the MB-50 laser from the now defunct Laser
Ionics, routinely
generated 65 watts into a power meter. Some manufacturers have built 60+ Watt YAG laser who's
lime-green beam appears as bright to the eye as a 200 watt Argon laser.
200 W Copper Vapour Lasers are commercially available from Oxford Lasers although we have not heard of them being
used in light show applications.
Q: Can you get rich doing laser light shows?
A: NO!
The laser and computer equipment, the personnel needed and the costs of producing the
shows are all very high. You can pursue lasers as a fun and interesting hobby since low power HeNe and diode lasers are available from many sources.
You can also design and build your own simple effects generation equipment and low cost scanners such as the Catweazle and Eye Magic scanners are available.
Professional Laser show companies spend thousands of dollars and hundreds of hours creating the shows and displays that you enjoy.
While you cannot get rich, you can make a reasonable living doing laser light shows.
Q: Can I put my hand into a laser beam at a show?
A:
Generally, NO! You can safely put your hands into any beams that are scanned onto the audience as they are dynamic and the power levels are safe.
Static beams (unmoving beams) can be dangerous and can cause burns or ignition of clothing - never put you hand into a static laser beam. You should never attempt to reflect a laser beam with a mirror or watch crystal as this may direct it into someone else's eyes causing
vision damage.
Q: Where can I found out more about how laser light shows work?
A: The How Laser Shows Work section of this web site has a diagram of a laser display system you
can click on. Each part of the system is more fully explained on the accompanying pages.
There are not many books available on the subject but you can find a short bibliography in the Laser Science
Project sections as well a glossary of
terminology, which gives more information about laser displays.
Q: Do you have to be licensed to do laser shows?
A: The rules and regulations on public laser shows and displays differ from country to country
although most countries follow the IEC-825 regulations. In the USA laser projection equipment needs a 'variance' and each show must be reported and have a 'site variance' issued by the
CDRH.
In Canada public shows and displays must be reported to the Radiation Protection Bureau in
Ottawa. If you plan to perform a public laser show, check with the authorities having jurisdiction over radiation protection and health in your area.
Q: How do they control the colours of the laser in shows?
A: Lasers are not like regular lights than can have their colour changed by placing gels (filters) in front
of them. Lasers produce only certain colours (frequencies; also called lines) of light.
For example, HeNe lasers produce only red light (at 629 nm approx.) while argon lasers produce blue and green
light on several frequencies. To produce a colour laser display, you need to have all colours present
in the beam first either by mixing a red Krypton or HeNe laser with an Argon laser, or using a White
Light laser (which produces red, yellow, green and blue light on a number of lines).
The simplest form of colour control is called a colour box. This uses dichroic filters mounted on
actuator arms to select one of 7 possible colour combinations (red, green, blue, yellow, cyan,
magenta and white) by subtractive colour. In full colour displays, an acousto-optic device called a
PCAOM is used to control the brightness of each line allowing for a full spectrum of projected
colours by additive colour (see the Projector page in the How Laser Shows Work topic).
Q: How are the images produced in laser shows?
A: The images can be either abstract or graphics.
Mixing of signals from a number of analogue oscillators is usually used to produces abstract images although they can also be produced with a
computer graphics system.
Laser graphics computers store images as a series of points (like a connect-the-dots picture).
The individual frames of the animation are played back in sequence to create the illusion of motion as in a
cartoon. The points that make up the image are converted by the computer into voltages that drive
the scanners. The scanners use small mirrors mounted on galvanometers at right angles to each other
to control the vertical and horizontal deflection of the beam (see the Scanners page in the How Laser
Shows Work topic). The points in the image are refreshed (re-drawn) many times a second by the
scanners so that your eye is tricked into seeing an image. The rapid projection of a sequence of
slightly different images gives the illusion of movement.
Q: How much laser power do I need to make a visible beam?
A: Small lasers such as a 5mW HeNe can make a visible beam provided they are operated in total
darkness with particulate matter [smoke or dust] in the air. To make a more visible beam you would
need an Argon, Copper Vapor or YAG laser as the eye is more sensitive to green light.
A 100 mW argon laser would make a visible beam in a dimly lit room with smoke or dust in the air.
To make high visibility laser beams such as the kind you see in clubs/bars, you would need at least
a 1 watt Argon laser as these locations have plenty of ambient light. Typically the lasers used in
clubs/bars are in the 3 to 5 watt power range. The lasers used in outdoor shows can vary from 5
watt Copper Vapor lasers to 20 watt argon lasers, to 60+ watt YAG lasers.
[ General laser FAQ
| Laser show FAQ
| Sam's
Laser FAQ ]
|
