ILDA
ILDA is an acronym for the International Laser Display Association. ILDA is the organization that sets the Industry Standards for Entertainment Laser Shows. They do everything from promoting a better understanding between laser display professionals and regulatory agencies to setting the technical standards for the ILDA connector on the back of your Laser Projector plus much more.
ILDA cable/connector
The ILDA cable/connector is a “D”-shaped DB-25 connector with 25 pins/wires that sends signals from a laser show controller to an ILDA controlled laser projector. The parallel port on most computers uses a DB-25F female connector. You can purchase DB-25 connectors, cables and switch boxes at most computer and electronics stores. This wide availability is one reason that ILDA chose the DB-25 for its ILDA Standard Projector connector.
Signal name
Pin
Notes
X+
1
-5 to +5V
Y+
2
-5 to +5 V
Intensity/Blanking+
3
0V to +5V
Interlock A
4
Should be used in Interlock loop
Red+
5
0V to +5V
Green+
6
0V to +5V
Blue+
7
0V to +5V
Deep blue+
8
0V to +5V
Yellow+
9
0V to +5V
Cyan+
10
0V to +5V
Z+
11
Depth Z (not intensity), -5 to +5V
Not connected
12
Shutter
13
0V to +5V (referenced to pin 25)
X-
14
-5V to +5V
Y-
15
-5V to +5V
Intensity/Blanking-
16
0V
Interlock B
17
Should be used in Interlock loop
Red-
18
0V
Green-
19
0V
Blue-
20
0V
Deep blue-
21
0V
Yellow-
22
0V
Cyan-
23
0V
Z-
24
-5V to +5V
Ground
25
Common ground and Cable shield
Laser projector
Any Laser system which projects laser output; most entertainment lasers have one or more internal laser sources and an optical scanning system that will allow for the display of 2D or 3D objects. These can be controlled by DMX with locally stored animations, or via ILDA computer control. ILDA controlled laser projectors give you more control over what can be displayed by the device by allowing it to be controlled by computer operated hardware (DAC) and software. Some laser hardware controllers come with the ability to have content created in software, uploaded to the hardware controller’s memory card, and triggered by DMX input signals.
Optical Scanning system (Galvos/Scanners)
The system that physically draws the images with laser light using motors with mirrors mounted on shafts vibrating back and forth. With two motors, placed in the correct orientation, a laser beam can be moved on both the X and Y axis to create 2D and simulated 3D images. These motors are driven from amplifiers that are receiving the ILDA signal from a hardware controller or other control device.
Laser Modules
The light source of a laser projector; Laser modules were first gas laser tubes which hold a specific gas, argon, or mixture of gases, helium-neon, and a large amount of power is used to excite the gas to create a laser beam. This technology evolved to DPSS, or Diode-Pumped Solid State lasers where a very high powered infrared light source is focused onto a specific crystal (Nd:Yag) to create various lasers wavelengths (colors). Most recently, Diode laser technology has become the standard for laser show laser modules. This technology uses far less electrical power applied to a tiny crystal to create laser light.
Most laser projectors have one to three laser modules (red, green, and blue) but the ILDA standard provides 6 color channels to control up to 6 different color lasers. A laser module’s color is determined by its wavelength which is measured in nanometers (nM).
Laser modulation/blanking
Externally caused change in laser power to turn the laser on/off and fade. Blanking, or tuning a laser module all the way off, is used in drawing animations to separate image components so they are not connected by a low power line. For example, if the word “TEXT” is projected, a properly blanked laser would turn off (0% power) between each letter of the word.
In modern laser modules there are two different modulation, or blanking options on laser drivers; Analog or TTL (digital).
Analog modulation turns the laser power up or down in a linear fashion like a volume control; TTL or digital modulation is on or off, like a power switch. With a full RGB laser projector, Analog modulation provides the ability to fade and mix colors to give a full gambit of color choices along with grey scale. TTL modulation on a RGB laser projector will allow for 7 colors, red, yellow, green, cyan, blue, magenta, and white.
Laser module power is measured in milliwatts (mW) or Watts (W); 1W = 1000mW.
Laser modules are also rated or measured by how much the beam widens or spreads the further the beam gets from the laser module. This is called divergence and is measured by milliradiant (mRad).
Interlock
An electrical “loop” wired to various points in a laser projector (Remote connector for e-Stop control, Case contacts to stop laser if the case is opened, scan fail device in case of a scanner failure, etc.). In the United States an interlock is one of several requirements a laser projector may need to be certified for a CDRH Variance which is required for any laser projector to be used in public. (CDRH: Center for Devices and Radiological Health, a division of the FDA that regulates radiation emitting devices, X-Rays, Microwave ovens, Lasers).
Shutter
A mechanical shutter is a safety device that when activated will block the path of the laser modules before they hit the scanners so no unintended laser emission occurs outside the laser projector. The shutter is usually connected in some way to the interlock loop so it is activated when the interlock is interrupted.
Mask
Anything used to physically block the audience from where the laser projector will project images. Many projectors now come with a metal plate just past the aperture window that can be adjusted to “mask” the lower portion of where the laser projector can project effectively blocking everything below where the laser is set to display.
DAC
Digital to Analog Converter. The DAC is the main laser control hardware that converts digital signals created in Laser Show control Software into analog electrical signals (wave forms) that a Laser Projector accepts over the ILDA cable.
There are currently 3 types of DACs being used in the Entertainment Laser Industry, differentiated by how they connect to the control computer.
The first, and most legacy type of DAC, is the ISA/PCI DAC which is a computer card that installs inside a computer via the ISA or PCI slot. Many manufactures of these have created laptop friendly enclosures that connect via network.
The second type of DAC is the USB DAC, which is connected to the computer via USB. These devices usually have a smaller footprint than the PCI DAC inside of a laptop friendly enclosure but can be limited by the relatively short cable length of the USB Standard.
The third type of DAC is Ethernet DAC which connect to a computer over network or Ethernet. This type of DAC is quickly becoming the industry standard because it gets rid of the need for a long ILDA cable going from the DAC to the Laser Projector.
DMX
An Entertainment Industry technical standard that controls almost anything (lasers, lights, prop movements, fog/haze machines, etc). This signal can be transported across several mediums, 3 or 5 pin XLR cable, and over network via ArtNET. DMX is a digital signal that represent numerical values between 0 and 127 that are communicated on different channels. The current DMX standard uses a 512 channel Universe.
MIDI
MIDI is short for Musical Instrument Digital Interface) is another Entertainment Industry technical standard, similar to DMX, that describes a protocol, digital interface and connectors and allows a wide variety of electronic musical instruments, computers and other related devices to connect and communicate with one another. MIDI devices and consoles can be used to control some ILDA Laser control software platforms.
OSC
OSC stands for Open Sound Control which is a protocol for networking sound synthesizers, computers, and other multimedia devices for purposes such as musical performance or show control.
Time Code
Time code, is an electronic signal which is used to identify a precise location in digital systems and on time-based media like audio or video tape. It was developed by the Society of Motion Picture and Television Engineers and one version is called by this acronym, SMPTE. Time code can be used to synchronize many elements of a production together using SMPTE audio, ArtNET, MIDI, and several other “flavors”.
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