Lasers in Sci-Fi
This franchise’s “lightsabers” are often mistaken for lasers, but real lasers don’t stop in mid-air.
What is Star Wars?
A laser is highly directional because of this property of its wavefronts, meaning they are all “in step.”
What is coherence?
Barcodes in grocery stores are read using this common low-power type of laser.
What is a diode laser?
Most lasers use two of these reflective elements to form an optical cavity.
What are mirrors?
When a material absorbs laser energy and re-emits it as visible light, it is exhibiting this process.
What is fluorescence?
Captain Picard might remind you that the Enterprise doesn’t use lasers but these directed-energy weapons instead
What are phasers?
“Laser” stands for Light Amplification by this physical process.
What is stimulated emission?
This medical eye procedure reshapes the cornea using an excimer laser.
What is LASIK?
The simplest transverse mode of a laser, often shown as a smooth circular beam, is this mode.
What is TEM₀₀?
Radiation pressure can trap microscopic particles using focused laser beams in devices known as these.
What are optical tweezers?
In “Goldfinger,” Bond is nearly cut in half by this type of laser, which didn’t actually exist in such a portable form in 1964.
What is an industrial cutting laser ( or laser cutter)?
To achieve laser action, atoms must be driven into this non-equilibrium state with more excited than ground-state population.
What is population inversion?
Laser rangefinders determine distance using this physical quantity measured via time-of-flight.
What is the speed of light?
The distance over which a beam remains nearly the same size before diverging significantly is known as this length.
What is the Rayleigh range?
The Doppler effect allows lasers to cool atoms, provided the laser frequency is tuned slightly below this atomic feature.
What is an absorption resonance?
In most sci-fi movies, you can see laser beams travel through air. In reality they only become visible because of this phenomenon involving particles.
What is (Rayleigh/Mei) scattering?
Real laser beams spread out over distance due to this wave phenomenon, unavoidable even for ideal Gaussian beams.
What is diffraction?
Manufacturing often uses CO₂ or fiber lasers for this process, which removes material by melting or vaporizing it.
What is laser cutting or ablation?
Changing the curvature of cavity mirrors can select specific spatial modes by altering this stability parameter.
What is the cavity stability condition (g-parameters)?
Short-pulse lasers can reach extremely high peak powers because this quantity is very small.
What is pulse duration?
Sci-fi often shows lasers imparting large “kickback,” but real photons only transfer momentum via this small force.
What is radiation pressure?
In mode-locked lasers, extremely short pulses arise because many cavity modes add together with fixed phase relationships, a process known as this.
What is constructive interference? (or phase locking)
This laser-based technique in atmospheric science measures distance and composition by sending pulses and detecting reflections.
What is LIDAR?
Some lasers support many wavelengths at once due to cavity resonances, each of which must satisfy this integer-multiple condition relating length and wavelength.
What is the standing-wave condition (mλ/2 = L)?
Laser ablation thresholds depend on this material parameter that measures how well a solid resists heat flow.
What is thermal conductivity?