The Gysin Dream Machine

The dream machine is a stroboscopic flicker device that produces visual stimuli. Artist Brion Gysin and William S. Burroughs's "systems adviser" Ian Sommerville created the dreamachine after reading William Grey Walter's book, The Living Brain.
In its original form, a dreamachine is made from a cylinder with slits cut in the sides. The cylinder is placed on a record turntable and rotated at 78 or 45 revolutions per minute. A light bulb is suspended in the center of the cylinder and the rotation speed allows the light to come out from the holes at a constant frequency of between 8 and 13 pulses per second. This frequency range corresponds to alpha waves, electrical oscillations normally present in the human brain while relaxing.

A dreamachine is "viewed" with the eyes closed: the pulsating light stimulates the optical nerve and alters the brain's electrical oscillations. Users experience increasingly bright, complex patterns of color behind their closed eyelids. The patterns become shapes and symbols, swirling around, until the user feels surrounded by colors. It is claimed that using a dreamachine allows one to enter a hypnagogic state.

The hypnagogic state is a peculiar sensory experience that marks the onset of sleep. Also known as hypnagogia, it can include a mesmerizing array of visions, sounds, bodily sensations and insights as you sail through the borderland state.
Most people will be familiar with the geometric imagery of hypnagogia as they fall asleep at night, or simply remain quietly aware during meditation. This can evolve into the sight of familiar faces, landscapes, voices and even music.
As the increasingly complex patterns flow across your field of vision, you feel drawn into the hypnotic hypnagogic state which, with focus, can be manipulated at will. What many people don't realize (because they fall asleep) is that imagery can lead directly to the dream state and, for our purposes, lucid dreams.

This experience may sometimes be quite intense, but to escape from it, one needs only to open one's eyes. A dreamachine may be dangerous for people with photosensitive epilepsy or other nervous disorders. It is thought that one out of 10,000 adults will experience a seizure while viewing the device; about twice as many children will have a similar ill effect.

There were some online Gysin generators, but most have disappeared.
This is as close as one can get to the effect with a gif animation.
Careful if you are sensitive to such things.