Interactive lasers

(WIKI IN PROGRESS)

Goals

The main idea is to add interactivity to "leisure" lasers. i.e with a gamepad one can play to old style vector games on city buildings. See picture at bottom.

Different levels of complexity are possible. Commercial lasers uses ilda files/connections to draw whatever you want, but you can build your own, see hardware section.

• The very fast and easy plan is to switch ilda scenes according to some inputs. You can use already made ilda files (see download section) in a SDcard plugged inside the laser fixture and use DMX protocol to switch. DMX usb cards are cheap, usually we use enttec ones. DMX controlled lasers are cheaper than
• If the plan is too draw live, it depends on the laser fixture DIY or commercial. Lot of possibilities depending on the number of colors, from using an arduino, a 5.1 USB soundcard upt to use commercially (opensource) cards using the standarts ilda connect ports.
• In any way, such lasers must feature X- and Y-scanners (i.e. galvanometer-moved mirrors) in order to position the beam accurately

Hardware

Obviously there is DIY Lasers and commercial ones and there is a bunch of cards integrating some DACs to talk to the laser fixture.
A great forum for bootstrap your project is laser freak that comes in different langages.

We play with two different setups :

• a green DIY laser made at la Blackboxe with a lasershark USB DAC card.
• an ilda DB25 ports RGB commercial laser for clubs with an Etherdream USB DAC card. Obviously is much more expensive but has some great advantage : the ether dream is directly tcp/IP controlled, so you can imagine very cool projects with very easy setup and of course the programming langage you prefer.

Commercial Lasers

Warning ! Not all lasers can draw anything ! Only the ones featuring scanners (i.e. galvanometer-moved mirrors) for the X- and Y-axes can do it (unlike the cheapest ones, which only draw random patterns).

On commercial lasers, the standard way to drive the beam is the DB25-connector-based ILDA interface (source : laserfx.com). It is based on analog differential control signals.

Therefore you'll need some external hardware capable of outputting such signals, be it standalone or controlled by a host computer. Such hardware is usually named concisely "DAC".

DIY projects

[1] : a DIY laser projector made from scratch.

Even the galvanometers are home-built !

In particular, there is a detailed study of the design of the galvanometers' servo loop control : galvanometers feature inertia like any mechanical devices, and achieving fast and accurate moves requires to "compensate" the galvanometers' drive signals with respect to their sensed position.

Ether-dream dac

This is an ILDA control box which can either work as standalone (displaying a sequence of ILDA scenes tored internally or on an SD-card) or receive IP frames for driving the beam.

The firmware is open-source (but what about the hardware ?)

An "Asteroids"-variant game from Brandon Thomas (Echelon) on GitHub