This projector has been created from the very beginning to print images from files, using cyanotype or other historic photographic processes (one can name dichromate gum, bromoil, salt paper, Van Dike, wet plate collodion, and so on).
The main elements constituting this projector are :
- A laser. Near UV, as the vast majority of historic photographic processes are mainly UV sensitive. 405nm are widely available, and do the job very well.
- A pair of galvanometer mirror. With them the laser beam can be moved wherever we want to, fast and repetitively.
- Something that can receive command and coordinates, and transform it to something that the galvo can use, namely a variable tension. For that purpose an Arduino were first chosen, with a 24 bits DAC module.
- Something that can use an image file and transform each of its pixel into a coordinate (X and Y) and intensity value. And play with trigonometry too, as the galvanometers move around an axis. That kind of thing is called a program. And it has to have a graphic user interface, as this laser is intended to be used by people who can lack the abstraction ability needed to use a command line...
More to come !