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.
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.
Figure 1: One arrangement for producing and photographing a laser art pattern.
Caution: Always follow common sense safety precautions when using any kind of laser to create laser art. Never allow the laser beam or its reflections to strike your eyes or the eyes of an onlooker. Avoid pointing lasers directly into a camera for the focused beam may damage the camera's sensor array.
This is a very flexible project, and a variety of supplies can be used. The basic requirements include the following. (Jameco part numbers are shown in parentheses.)- Green laser pointer (P/N 223731) or
- Red laser module (P/N 310519) and 3-volt power supply or
- Do-it-yourself laser 650 nm laser diode, (P/N 182932) driver and 3 to 5 volt power supply
- Aluminum foil
- Diffuser screen (ground glass, waxed paper or Glad brand Press'n Seal Multipurpose Sealing Wrap)
- Digital camera with a macro setting for close-up photos
Note: This project is very flexible, so read on before deciding which supplies you will need.
The methods that follow can be used to form laser art patterns on a white card or a diffuser screen. Use a white card to decide if you like the patterns well enough to photograph them. Then either photograph the patterns on the card or through a diffuser screen. Ground glass is an ideal diffuser screen, but Glad brand Press'n Seal Multipurpose Sealing Wrap works well. For best results, the room lights should be very dim.
1. Figure 1 (above) shows a laser kaleidoscope made by wrapping a cylinder of flattened, previously crumpled aluminum foil around the business end of a laser pointer. Allow an inch or so of the foil cylinder to extend beyond the end of the laser. Tape the foil to itself so that the cylinder can be rotated around the laser. Point the laser at a white card and gently push one side of the cylinder extending from the laser toward the beam. When the foil intersects the beam, a complex pattern of light will appear on the card. Rotate the foil cylinder to alter the effect. Some positions may show a bright dot of laser light with lacy patterns of light off to one side. The diagram in Fig. 1 shows how to photograph the patterns through a diffuser screen.
2. Create a "comet" by reflecting a laser beam from the tapered, shiny end of a ballpoint pen toward a white card. Alter the position of the laser to provide a straight or curved tail behind a bright dot.
3. Create diffuse blobs by shining a laser beam through a sandwich bag or ground glass.
4. Create a diffuse blob with aluminum foil. Prepare the foil by placing a small square of foil dull side down on a mouse pad. Flatten the foil by stroking it with the round side of a Sharpie pen or other smooth, round object. Reflect the laser beam from the smoothed, dull side of the foil against a white card.
5. Use an optical fiber (Jameco P/N 171272) to create a very uniform blob of laser light. Simply shine a laser beam into one end of the fiber and place a white card at the opposite end. For best results, use a sharp hobby knife to cut each end of the fiber as flat as possible. Even without a flat end, the fiber will still form a diffuse blob of light.
6. Create a blob with emphasis points by smoothing a small sheet of foil as described above but with the shiny side down. Form parallel rows of creases in the shiny side of the foil by stroking across it with a comb. Stroke the comb across the foil at a right angle to the first stroke. Add more strokes at various angles if desired. Reflect a laser beam from the shiny side of the creased foil toward a white card.
7. Crumple a few square inches of aluminum foil and then flatten the foil. Reflect a laser beam against the shiny side of the crumpled foil toward a white card to see spectacular patterns. For more variety, press the crumpled foil against a mouse pad and stoke from several directions with a plastic comb. You can hold or mount the foil several inches or more away from the card or simply place the foil on a flat surface next to an upright white card.
8. Reflect a laser beam from a diamond or artificial gem stone toward a white card to create a pattern of bright dots.
9. Make long bars of smooth or structured light by shining a laser beam through the side (not the end) of an exposed length of plastic optical fiber (Jameco P/N 171272). The fiber forms a cylinder lens. Moving the laser with respect to the fiber will create considerable structure in the refracted laser beam.
10. Best for Last: Let the camera do all the work by glancing the laser beam across its lens while watching the images on the camera display. This method works well with many different digital and cell phone cameras.
As suggested by the modified title bar for this final section, you can process your laser art patterns using photo software. The colors in the title bar above, for example, were quickly altered by varying the hue in Microsoft Digital Image Pro 10. Countless other effects are possible. Follow your imagination, have fun, and remember to use care when using any kind of laser.
About Forrest M. Mims III
Forrest M. Mims III has written more than sixty books about science, lasers, computers, and electronics. Many of his books describe electronic circuits and projects that he personally builds and tests. When he isn't writing books, he does various kinds of scientific research, writes magazine and newspaper articles, and teaches experimental science at the University of the Nations in Hawaii. For more information, visit www.forrestmims.com.