Femtosecond lasers create 3D midair plasma displays you can touch (2015)
Femtosecond-laser “midair plasma” displays that create visible pixels by ionizing air briefly raised hopes for touchable 3D holograms, but nearly a decade on they have not reached practical use. Commenters point to the huge cost and complexity of femtosecond laser systems, serious safety issues around burns and eye damage, noise, and byproducts like ozone or NOx, making it very hard to build an eye‑safe, consumer-ready device. Many suspect the core techniques now live mainly in military or niche research applications, likening the concept to other volumetric or exotic display technologies that were technically impressive yet commercially unviable.
State of the Technology / “What Happened?”
- Original work is from 2015; multiple commenters note the absence of follow‑up or products.
- Consensus leaning toward “went nowhere” for consumer use, largely due to cost, complexity, and safety.
- Some speculate the technology may continue in military or classified contexts, citing later patents and related weapon research.
Cost, Size, and Engineering Constraints
- Femtosecond lasers used in labs and medicine are described as very expensive (hundreds of thousands of dollars) and physically large, often filling optical benches.
- Systems need complex optics (prisms, diffraction gratings, pulse stretching/compression), not just a simple compact “projector.”
- Practical, cheap, solid‑state versions are imagined but not known to exist in the thread.
- Beam scanning requires galvos and dynamic focusing; maintaining enough intensity for air breakdown at distance is described as technically hard.
Safety and Health Concerns
- Core issue: the device creates actual plasma in air. It can burn skin and potentially damage eyes; videos show visible fingertip burns.
- Commenters compare risk to fireworks more than to conventional displays.
- Eye safety is a major worry: powerful, unconfined IR lasers that can ionize air are seen as unacceptable for public or consumer spaces.
- Discussion branches into real-world experiences of laser- and light-induced retinal damage and the difficulty of noticing it early.
Noise, Ozone, and Byproducts
- Measurements cited around ~77 dB at very close range; considered tolerable but unpleasant, with noise scaling with brightness/resolution.
- Some wonder about use as a sound source.
- Concerns raised about ozone and NOx generation in air plasmas; exact levels remain unclear.
Military and Weaponization Angle
- Related research includes plasma-based decoys, area-denial concepts, “set to stun” nonlethal weapons, and “screaming balls of plasma” for psychological operations.
- Several commenters suggest this risk/benefit profile makes more sense for defense than for displays.
Comparison to Other Exotic Display Tech
- Thread recalls past “holographic” or volumetric systems (water-vapor projection, field emission displays, transflective LCDs, lenticular 3D, commercial volumetric units like Voxon).
- Pattern noted: many visually striking demo technologies fail to become practical, especially when 2D displays already serve most needs safely and cheaply.