Want to liven up your computer desktop or home page with catchy imagery? There are plenty of commercial images you can download, but a laser pointer and a digital camera will allow you to create original and spectacular desktop and home page background images that will make you the envy of the office--or at least cause your colleagues to ask where you found them.
While this is not a traditional electronics project, it makes use of one of the most phenomenal success stories of modern electronics, the semiconductor laser diode. The first laser diodes were demonstrated in 1962, but they could be operated only in brief pulses and emitted only invisible near-infrared radiation. Decades were required before reasonably priced, continuously operating (CW) laser diodes became available. They emitted just one wavelength: red. In recent years frequency doubling crystals have been widely used to transform the infrared emitted by high-power laser diodes into brilliant green beams. This and other new developments have provided laser diodes that emit across the visible spectrum.
While today's principle application for laser diodes is in laser read/write systems, they have many other important applications in sensing, intrusion alarms and both optical fiber and free-space communication. They are also useful for making miniature laser light shows and laser art, the topic of this Circuit Recipe.
Step 1: How to Create Laser Art Patterns
The coherent properties of a laser beam provide an ideal tool for creating highly complex interference patterns, and reflecting a narrow laser beam from various surfaces can produces strikingly beautiful splashes of laser light.
Figure 1 shows one of many simple ways to create laser art patterns. The key ingredient for this recipe is a square of aluminum foil wrapped around the business end of a laser pointer or module. The foil is crumpled to provide a field of highly complex reflective surfaces. It is then rolled around the end of the laser pointer with the shiny side facing inward. The open end of the foil is partially pushed in to intercept and reflect the laser beam. The laser is pointed toward a diffuser screen (see below), and the pattern formed on the screen is captured by a digital camera on the opposite side of the screen.