Introduction
The first working laser was developed in 1960. Since then, there have been multiple applications in science and in industry. Applications include barcode readers, LiDAR, Optical tweezers, Laser cutting, Laser cooling and ultra-fast photography.
A laser stands for light amplification by stimulated emission of radiation. A laser is a very narrow beam of light of waves with a narrow wavelength bandwidth, and is only created artificially. The basic principles behind a laser is the amplification of light by the use of mirrors and light. A laser tube is filled with a gas, such as a helium-neon gas, which amplifies light. Mirrors are placed at both ends, and once the a light is introduced in the system, the light bounces back and forth, being amplified each time. As the light is amplified, the waves of light come into phase, and becomes a coherent beam of light. One mirror is partially transparent, and a portion of the amplified light will beam through the mirror. The output is a laser beam.
This article will focus on three applications, the LiDAR, optical tweezers, and laser cooling.
LiDAR
LiDAR stands for Light/Laser Detection and Ranging. It is a method that measures the distance to something by beaming a laser and measuring the time it takes for a reflection to reach a sensor. This technology is used to make high-resolution maps. LiDAR is used in many fields to “see” things better. For atmospheric physics, the LiDAR is used to measure the density of comprising elements, which tells us the temperature as well. For geology and seismology, LiDAR and GPS is used to monitor crustal movements, which helps to prepare for anticipated earthquakes faster. For oceanography, LiDAR is used to measure the biomass of the ocean near the surface. Recently, LiDAR is being used in automation of vehicles, processing accurate information of the surroundings in 3D.
Optical Tweezers
Optical tweezers trap small particles into place by using a focused laser beam, and allows for manipulation. Optical tweezers can be used to trap viruses, bacteria, cells, particles, and strands of DNA. It can track movement, apply and measure forces, or move things safely.
Laser Cooling
Lasers are commonly used to heat something up, but they can also be used to cool substances down.
This uses the principle of the Doppler effect. Any substance has a specific bandwidth of light that it absorbs. A laser with a wavelength that is slightly longer than the optimum wavelength is beamed at a substance with a velocity. When the substance is traveling toward the beam, the substance feels the wavelength being shorter than reality from the Doppler effect, and the light is absorbed. The momentum when light is absorbed slows the substance down. Lasers are beamed from both directions in the x, y and z axis to ensure that the substance loses velocity.
Temperature is basically how much velocity a particle has, so by decreasing the velocity, the substance is cooled down. We can now reach a temperature that is really close to absolute zero. Combined with magnets, scientists can achieve extremely low temperatures: one tenth of a billionth degrees above absolute zero, until particles experience a state called the Bose-Einstein condensate where particles achieve a collective quantum state which resembles a large wave.
This low temperature has many applications in observing and experimenting with scientific phenomena. Examples include states of superconductivity and superfluidity.
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[2] Takahashi, Yoshiro. (2008). “Laser Cooling Techniques and Its Application”. https://annex.jsap.or.jp/photonics/kogaku/public/37-07-sougouhoukoku.pdf. Last Accessed: 2020/02/21.
[3] Sixty Symbols. (2018). “Optical Tweezers and the 2018 Nobel Prize in Physics – Sixty Symbols”. https://www.youtube.com/watch?v=XjXLJMUrNBo. Last Accessed: 2020/02/21.
[4] Schweber, Bill. (2019). “What… Use Lasers and LEDs for Cooling?”. Electronics cooling. https://www.electronics-cooling.com/2019/05/whatuse-lasers-and-leds-for-cooling/. Last Accessed: 2020/02/21.
[5] Loeffler, John. (2018). “11 Incredible Uses of Laser Technology”. Interesting Engineering. https://interestingengineering.com/11-incredible-uses-of-laser-technology. Last Accessed: 2020/02/21.
[6] Starr, Michelle. (2018). “NASA Is About to Create The Coldest Temperature in The Universe, Using Lasers in Space”. Science Alert. https://www.sciencealert.com/coldest-spot-in-universe-nasa-iss-cold-atom-laboratory-bose-einstein-condensates. Last Accessed: 2020/02/21.
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