Serving tech enthusiasts for over 25 years. TechSpot means tech analysis and advice you can trust.

Through the looking glass: When The Slow Mo Guys turned their high-speed lenses on the Virtual Boy, the experiment wasn’t about nostalgia; it was about engineering curiosity. In their latest video, host Gavin Free dismantles Nintendo’s 1995 attempt at stereoscopic gaming and reveals an optical system that was decades ahead of its time, even if the hardware itself was a commercial failure.

At more than a million frames per second, Nintendo’s strangest console finally gives up its secrets. Released between the Super Nintendo and Nintendo 64, the Virtual Boy promised true 3D imagery without glasses or external displays. The concept was bold, yet the execution was famously awkward: a monochrome red-and-black display, limited launch titles, and reports of eye strain helped end its lifespan within a year.

But buried inside the bulky tabletop headset is a surprisingly elegant display mechanism – one that used vibration, mirror oscillation, and human persistence of vision to fake what early VR couldn’t quite deliver.

The Slow Mo Guys uncovered these details in a YouTube video that breaks down the console’s inner workings.

Inside the headset, host Gavin Free finds two vertical arrays of red LEDs – each just one pixel wide but 224 pixels tall. Instead of projecting onto a standard screen, each LED column reflects light through a magnifying lens and onto a 45-degree mirror. The mirrors sweep back and forth 50 times per second, effectively "painting" a horizontal image across each eye.

The result is a 384-by-224 image that appears stable only because the brain integrates the flickering into continuous motion, similar to how CRT televisions once drew frames line by line.

Using a Phantom TMX7510 camera – capable of capturing up to 1.75 million frames per second – Free isolates what users never could: the rhythm behind the Virtual Boy’s stereo illusion. At 100 frames per second, the flicker is unmistakable.

By 80,000 frames per second, the LED motion almost disappears, revealing the mirrors’ role in creating that illusory depth. Each eye sees alternating frames, allowing one mirror to reset while the other displays its image – a mechanical dance of synchronization and split-second timing.

When Free loads Galactic Pinball and pushes the speed to 450,000 frames per second, the full pattern emerges. Each frame is built line by line from left to right, amounting to roughly 38,400 individual LED flashes per second across both eyes.

The slow-motion footage shows how briefly each pixel turns off before reigniting for the next pass, a process fine-tuned to maintain contrast and brightness without smearing the image.

With a macro lens attached, Free dives deeper still. At lower magnifications, edges flicker as the LEDs alternate phases. At 875,000 frames per second and a reduced 64-pixel vertical resolution, the scan lines finally separate into distinct flashes.

Also check out: Virtual Reality Then: A Look Back at the Nintendo Virtual Boy

Pushing beyond one million frames per second clarifies the engineering trick that made the display possible: each LED operates in three quick illumination phases followed by a short blackout, creating variable brightness without extending the time required for each sweep.

The 3D illusion depended on the disparity between the two eyes. Each received a slightly different image at precisely synchronized intervals, allowing the brain to stitch together depth from flat projections.

These stages simulate gradations of intensity using nothing but binary on-and-off pulses – a necessity, since multicolor LEDs were too large and costly in 1995. Red was the only viable option. In effect, Nintendo engineered a head-mounted raster display years before microdisplays or OLED panels could fit inside a headset.

By flashing each eye’s display alternately, Nintendo avoided ghosting and ensured the mirrors had time to reset between sweeps. There was no backlight, no LCD shutter. Just mirrors, LEDs, and persistent vision – a mechanical analog to digital stereoscopy.

Free’s video transforms what was once a quirky relic into a case study in optical engineering. The Virtual Boy’s commercial shortcomings obscured how ingenious its design actually was: a fully self-contained 3D display system that worked on principles more akin to early cinema projectors than to modern VR.