PRECISION INSTRUMENT BASED ON LASER
Laser stands for Light Amplification by Stimulated Emission of Radiation.
Laser instrument is a device to produce powerful, monochromatic, collimated beam of light in which the waves are coherent. Laser development is for production of clear coherent light. The advantage of coherent light is that whole of the energy appears to be emanating from a very small point. The beam can be focused easily into either a parallel beam or onto a very small point by use of lenses A major impact on optical measurement has been made by development in elector optics, providing automation, greater acuity of setting and faster response time. Radiation sources have developed in a number of areas; the most important developments are light emitting diodes and lasers. The laser is used extensively for interferometry particularly the He- Ne gas type. The laser distance measuring interferometer has become an industry standard. This produces 1 to 2mm diameter beam of red light power of 1MW and focused at a point of very high intensity. The beam begins to expand at a rate of 1mm/m. The laser beam is visible and it can be observed easily. This is used for very accurate measurements of the order of 0.lµm are 100m.
Metrology lasers are low power instruments. Most are helium-neon type. Wave output laser that emit visible or infrared light. He-Ne lasers produce light at a wavelength of 0.6µm that is in phase, coherent and a thousand times more intense than any other monochromatic source. Laser systems have wide dynamic range, low optical cross talk and high contrast. Laser fined application in dimensional measurements and surface inspection because of the properties of laser light. These are useful where precision, accuracy, rapid non-contact gauging of soft, delicate or hot moving points.
Principle of Laser
The photon emitted during stimulated emission has the same energy, phase and frequency as the incident photon. This principle states that the photon comes in contact with another atom or molecule in the higher energy level E2 then it will cause the atom to return to ground state energy level E1 by releasing another photon. The sequence of triggered identical photon from stimulated atom is known as stimulated emission. This multiplication of photon through stimulated emission leads to coherent, powerful, monochromatic, collimated beam of light emission. This light emission is called laser.