Inducing visual effects using MAGNETIC FIELDS.......

The first report of electrically induced visual sensations was in 1755 by
     Leroy, who reported that he had passed the discharge of a Leyden jar
     through the head of a man who was blind.  He reported that he saw
     flames passing rapidly downward.
In 1792, Volta reported light sensations produced by galvanic current.
     In a letter dated 1800, he wrote that he could see light flashes only
     at the make and break of current flow and could be produced with
     electrodes placed on various parts of the head.
In 1798, Ritter reported the flash at the make was brighter, a faint
     sensation prevailed during current flow.  He also noticed colors and
     that visual acuity was increased during electrical stimulation.
In 1896, D'Arsonval reported that time varing magnetic fields induced a
     flickering illumination within the visual field. This phenomenon
     occurs to stimulation by either pulsed or sinusoidal magnetic fields
     with frequencies less than 100 Hz.


These effects seem to be a result of external stimulation (pressure,
     electric, magnetic) of the PHOSPHENES from the retna of the eye.


Sensations that have been felt are: Pulsating, Flashing yellow-green, moving
     patterns and spots that went on and off.
The maximum sensitivity to sinusoidal magnetic fields is 20 Hz at about
     100 guass in the area of the eyes-head.
Thresholds as low as 18 Hz and 50 guass have occasionaly produced effects.
At frequencies of 10 Hz the sensation is that of pulsating light, 15-35 Hz
     and low guass is that of gentle fluctuation, Above 40 Hz mosaiac
     patterns seemed to be produced, and above 70 Hz a flash is seen and
     lasting increased illumination.
If the magnetic field intensity is kept constant and frequency is varied from
      low to high the flicker rate seems to increase to a constant
      illumination.
Low frequency sensations can be experenced with the eyes open or closed. When
      open the effect is less pronounced.

Medical patients with their eyes removed due to glaucoma, the visual effects
     could not be induced, implicating the retna as the site of magnetic
     action.

Exposure to a magnetic field that varies between 10 and 100 Hz with magnetic
     intensities between 100 and 1000 guass can stimulate illumination
     effects.
The possibilities of using more than one magnetic field and multiple
     frequencies should be explored along with other effect frequencies and
     intensities.

The following is an article from IMAGE dated 15 DEC 1985.................

When Stephen Beck was 3 years old, he remembers closing his eyes and seeing
     colorfull images dance across his darkened field of vision.  "I remember
     seeing scintillating fields of ruby red, cobalt blue dots, and patterns
     that would weave in and out.  I always loved to watch that," he says.
     Beck's futuristic invention, the Phosphotron, traces its inspiration
     to that experence.
It was years before Beck found out that the images he noticed as a toddler
     were universal, though still mysterious, electrochemical phenomena
     called phosphenes.  The same reaction is invloved sees "stars" after
     a blow to the head.  A born tinkerer and budding artist, Beck became
     obsesed with finding a way to recreate those images. "I often dreamed
     about able to put an image right into a person's head without having
     them look at a canvas, or sculpture or even a video screen," he says.
In 1968, at the age of 18, Beck crafted his first Phosphotron prototype.
     By applying a carefully regulated flow of electricty around his eyes
     through a mask, he could experement with making fanciful patterns in
     his own head.
Beck put the Phosphotron on hold while he got a degree in electrical
     engineering from the University of Illonois, but he kept the idea in
     the back of his mind.  He became fluent in other forms of electronic
     wizardry and experemented with video art; in 1978 he founded his own
     electronics design and consulting firm in Berkeley, (Beck-Tech, 41
     Tunnel Road, Berkeley, Ca 94705). Now after being sidetracked for 17
     years, he has refined the Phosphotron into a revolutionary
     entertainment product.  Beck plans to make it available to consumers
     for a "few hundred dollars" by the middle of next year.
The Phosphotron consists of wrap-around goggles, which give the wearer a
     slightly alien look, and a power source, a nine volt battery in a hand
     held box.  A series of controls regulates the current, which stimulates
     different phosphene images.  The Phosphotron is equipped with resistors
     so that no more than a VOLT of current actually reaches the wearer-to
     ensure that the experence provides entertainment only.
What the viewer sees with the Phosphotron, according to its inventer, is "a
     vocabulary of visual effects that range from very directional left-right
     up-down sweeps of light to much more rapid pulsations, which break into
     what I call micro-textures.  For example, you might see a whole field of
     little trianglar forms-sort of what you might see in a microscope-but
     they're all scintillating, vibrating and moving.  At certain frequencies
     color effects occour."
Beck likes to demonstrate the Phosphotron by equipping about a dozen people
     at a time with the goggles and putting himself at the controls.  An
     accomplished keyboardist, Beck has composed symphonies for the
     Phosphotron's imagery and he plays music during the sessions, gearing
     the electrical impulses to the music.
The Phosphotron asks for a redefinition of the boundaries of art and
     technology, Beck suggests, adding that "internal vision" is the next
     logical medium for visual artists.
But Beck's device has possibilities beyond art and entertainment: He is
     hopefull that the Phosphotron may one day aid in the diagnosis and
     treatment of blindness.
"I don't want to raise any false hopes, but maybe we can find a way, with
     certain types of blindness, where a phosphene stimulation could trigger
     some kind of visual effect," he says.  A couple of groups who work with
     the blind have shown intrest, he adds.
Because he's exploring uncharted territory, whenever Beck talks about the
     artificial creation of phosphenes he issues a warning to the curious:
     Dont go hooking batteries or wires up to your eyes. "It's very, very
     dangerous if you don't know what your doing. Even the minutest
     electrical current passed into the body at the right place can
     literally kill you," he warns...................


     END