Iplay pedal steel guitar and banjo in several bands, and we enjoy performing
all over northern California.
However, as small independent
artists we aren’t performing in
venues with full lighting boards.
I’ve been searching for a way
to give our performances the
kind of visual elements that
can otherwise only be
achieved by true lighting artists.
Years ago, I saw a piece
that could light up with
different colors to the bass,
mid-range, and high
frequencies in a recording, but
I wanted more. Likewise, audio software on standard PC
and Mac computers has visualization software that seems
to respond to the music, but it lacks the satisfaction of
analog art and doesn’t respond to all the unique sounds
and rhythms.
As a musician, inventor, and laser enthusiast, I decided
to draw on all my hobbies and try to make something
myself. By programming the software and combining
lasers, stained glass, and motors, I have created a light
machine that has unique responses to each tone,
frequency, and beat, and can enhance the listening
experience for live shows or recordings of your favorite
music.
How It Works
It’s five inches tall ( 7. 5” with stand), 14 inches wide,
and 15 inches deep, and is made of wood, plastic, motors,
and electronics. I directed the lasers through slowly
rotating pieces of clear bumpy stained glass.
The music is divided into six different frequency bands
which then control the brightness of the lasers. Two sets
of red, green, and blue lasers combine into each of two
beams with all three colors, and another separate laser
shows a pure red beam.
I thought that the three beams combined would give
me one color that is the sum of the three colors. Then,
there would be three beams: one red, and two of some
different colors. I was wrong, but it turned out even better
than I hoped. I got rainbows!
The inexpensive laser diodes are not perfectly shaped
round beams, so even lining them up nicely does not
combine them perfectly. Also, the bumps in the stained
glass separate the colors slightly, just as a prism separates
white light into its component colors. The colors are
programmed to change in response to the music, and the
different patterns from different beams through different
pieces of glass make shapes and colors change and evolve
into moving rainbows. Check out my video at
https://www.youtube.com/watch?v=dCAF8E4Qjp0 and
see what it does with five different pieces of music. The
video doesn’t capture the vividness of the colors or the
unique character that laser light has, but it does give you a
general idea.
The music is input through an op-amp mixer,
combining right and left channels into one. A graphic
equalizer display filter (MSGEQ7) analyzes the music and
separates it into six frequency bands. A microcontroller
(PIC18F4620 at 40 MHz) reads this information and puts
it out through constant-current LED drivers (MAX16819)
to control the lasers and make them individually reactive
to each of the six frequencies. The code imparts a small
delay in the decay of the laser light at the peaks, so that
the lasers have a little more “sustain” than the music. This
keeps the lights from being too jumpy and smooths out
the display.
To combine the lasers, a green laser goes through an
angled laser-combining filter/mirror that allows the green
to pass, but reflects red. I’ll call it a mirror for this article.
The red laser comes in from the side and the result is a
combination of the red and green beams. This beam then
goes through an angled mirror that passes the red/green
May/June 2018 41
Post comments on this article and find any associated files and/or downloads at
www.nutsvolts.com/magazine/issue/2018/05.
■ FIGURE 1. Outside view shows the control panel and laser aperture.
Resources
Sam's Laser FAQ:
www.repairfaq.org/sam/las
ersam.htm
Instructable on front panel
making:
www.instructables.com/id/
Make-Your-Own-Front-Panels
Autodesk Fusion 360 free
trial; if you're a hobbyist,
you can use the program
for free:
https://www.autodesk.com/
products/fusion-360/free-
trial
Files for 3D printing:
Link to Motor Mount for
Fusion 360
http://a360.co/2sDPOoy
Link to Mirror Holder for
Fusion 360
http://a360.co/2BBAc7Q
Link to Laser Holder for
Fusion 360
http://a360.co/2EStJbC
