Industrial and Medical Applications of Laser

Spectroscopy

Most types of laser are an inherently pure source of light; they emit near-monochromatic light with a very well defined range of wavelengths. By careful design of the laser components, the purity of the laser light (measured as the “line width”) can be improved more than the purity of any other light source. This makes the laser a very useful source for spectroscopy. The high intensity of light that can be achieved in a small, well collimated beam can also be used to induce a nonlinear optical effect in a sample, which makes techniques such as Raman spectroscopy possible. Other spectroscopic techniques based on lasers can be used to make extremely sensitive detectors of various molecules, able to measure molecular concentrations in the parts-per-1012 (ppt) level. Due to the high power densities achievable by lasers, beam-induced atomic emission is possible: this technique is termed Laser induced breakdown spectroscopy (LIBS).Industrial and Medical Applications of Laser.

Heat Treatment

Heat treating with lasers allows selective surface hardening against wear with little or no distortion of the component. Because this eliminates much part reworking that is currently done, the laser system’s capital cost is recovered in a short time. An inert, absorbent coating for laser heat treatment has also been developed that eliminates the fumes generated by conventional paint coatings during the heat-treating process with CO2 laser beams.

One consideration crucial to the success of a heat treatment operation is control of the laser beam irradiance on the part surface. The optimal irradiance distribution is driven by the thermodynamics of the laser-material interaction and by the part geometry.

Typically, irradiances between 500-5000 W/cm^2 satisfy the thermodynamic constraints and allow the rapid surface heating and minimal total heat input required. For general heat treatment, a uniform square or rectangular beam is one of the best options. For some special applications or applications where the heat treatment is done on an edge or corner of the part, it may be better to have the irradiance decrease near the edge to prevent melting.Industrial and Medical Applications of Laser.

Lunar laser ranging

When the Apollo astronauts visited the moon, they planted retro-reflector arrays to make possible the Lunar Laser Ranging Experiment. Laser beams are focused through large telescopes on Earth aimed toward the arrays, and the time taken for the beam to be reflected back to Earth measured to determine the distance between the Earth and Moon with high accuracy.Industrial and Medical Applications of Laser.

Photochemistry

Some laser systems, through the process of mode locking, can produce extremely brief pulses of light – as short as picoseconds or femtoseconds (10−12 – 10−15 seconds). Such pulses can be used to initiate and analyse chemical reactions, a technique known as photochemistry. The short pulses can be used to probe the process of the reaction at a very high temporal resolution, allowing the detection of short-lived intermediate molecules. This method is particularly useful in biochemistry, where it is used to analyse details of protein folding and function.Industrial and Medical Applications of Laser.

Laser barcode scanners

Laser barcode scanners are ideal for applications that require high speed reading of linear codes or stacked symbols. From small products for embedded OEM applications to rugged laser barcode scanners for industrial use, Microscan offers a wide range of quality products to read linear barcodes and stacked symbols, with features such as high speed reading, wide field of view, symbol reconstruction, and aggressive decoding technology.

Laser cooling

A technique that has recent success is laser cooling. This involves atom trapping, a method where a number of atoms are confined in a specially shaped arrangement of electric and magnetic fields. Shining particular wavelengths of laser light at the ions or atoms slows them down, thus cooling them. As this process is continued, they all are slowed and have the same energy level, forming an unusual arrangement of matter known as a Bose–Einstein condensate.Industrial and Medical Applications of Laser.

Nuclear fusion

Some of the world’s most powerful and complex arrangements of multiple lasers and optical amplifiers are used to produce extremely high intensity pulses of light of extremely short duration. These pulses are arranged such that they impact pellets of tritium–deuterium simultaneously from all directions, hoping that the squeezing effect of the impacts will induce atomic fusion in the pellets. This technique, known as “inertial confinement fusion”, so far has not been able to achieve “breakeven”, that is, so far the fusion reaction generates less power than is used to power the lasers, but research continues.

Microscopy

Confocal laser scanning microscopy and Two-photon excitation microscopy make use of lasers to obtain blur-free images of thick specimens at various depths. Laser capture micro dissection use lasers to procure specific cell populations from a tissue section under microscopic visualization.

Additional laser microscopy techniques include harmonic microscopy, four-wave mixing microscopy and interferometric microscopy.

Barcode Scanners

Supermarket scanners typically use helium-neon lasers to scan the universal barcodes to identify products. The laser beam bounces off a rotating mirror and scans the code, sending a modulated beam to a light detector and then to a computer which has the product information stored. Semiconductor lasers can also be used for this purpose

Welding and Cutting

The highly collimated beam of a laser can be further focused to a microscopic dot of extremely high energy density for welding and cutting.

The automobile industry makes extensive use of carbon dioxide lasers with powers up to several kilowatts for computer controlled welding on auto assembly lines.

Garmire points out an interesting application of CO2 lasers to the welding of stainless steel handles on copper cooking pots. A nearly impossible task for conventional welding because of the great difference in thermal conductivities between stainless steel and copper, it is done so quickly by the laser that the thermal conductivities are irrelevant.

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