Article on LASER Technology in India

Laser (Light Amplification by Stimulated Emission of Radiation) ranks among the major fundamental inventions of this century. Invented in 1960 its unique properties make it a tool of exceptional precision and power.

The importance of laser was recognised by the scientific community in India fairly early and several institutions initiated research and development (R&D) projects, although modest ones, in this area in the mid-sixties. Since then, laser-related R & D programmes in India have expanded considerably and now encompass most of the important areas of laser applications. All the scientific departments of the Government of India have identified laser and its applications as a thrust area and have funded projects at academic institutions and national laboratories. However, the support given by the Department of Atomic Energy to develop lasers and explore their applications has been quite massive.

Dr Homi Bhabha, the founder of Indian atomic energy programme, always encouraged research in frontier areas of science, whether or not directly related to the atomic energy programme. Thus, a modest attempt to develop semiconductor lasers at the Bhabha Atomic Research Centre (BARC) was initiated in 1964 though at that time laser was in its infancy and its applications were limited. The first semiconductor laser in India was developed at BARC in 1965. This was a major achievement for India. In another significant breakthrough, an optical communication link using Indian-made semiconductor laser was established in 1966 between BARC and the Tata Institute of Fundamental Research (TIFR), a distance of 20 Kms. Dr Bhabha had constantly encouraged this activity and had often visited the laboratories and the site of the optical transmitter to encourage the scientists. Dr Bhabha’s successors continued his policy of encouraging research in frontline science after his tragic death in an air crash in 1967.

The laser-related activity in the Department of Atomic Energy got a fillip in 1987 when a new research institute called Centre for Advanced Technology (CAT) was established at Indore to carry out major R & D programmes in the areas of lasers and accelerators. Since its inception, CAT has made commendable progress in both the areas and is widely recognised as an important R & D centre of India. 

LASER Development

As the name suggests, CAT has given priority to developing technologies of important lasers and exploring their applications in industry, medicine and R&D. The first laser built at CAT was a copper vapour laser. It is the most powerful laser emitting visible light. Copper vapour lasers capable of giving up to 40 Watt average power had been developed at CAT. These lasers are also used to pump tunable dye lasers whose wavelengths can be changed. Several such lasers have been given by CAT to universities and other research laboratories for spectroscopic studies.

Another important laser developed by CAT is the carbon dioxide (CO2) laser. Incidentally, the CO2 laser was invented by a well-known Indian scientist, Dr C.K.N. Patel, who was then working at Bell Labs in the USA. CAT has developed technologies of several types of CO2 lasers namely, low power slow flow CO2 laser, high power fast flow CO2 laser, tunable CO2 laser and high-pressure pulsed CO2 laser and is also pursuing applications of these CO2 lasers in medicine and industry.

Laser surgery has many advantages over conventional surgery. In laser surgery, there is virtually no bleeding, far less trauma to the patients and healing is faster. Although the use of lasers in surgery is widespread in the western countries, its application in India was limited mainly due to the high cost of imported surgical lasers. CAT, therefore, decided to develop a surgical laser based on a 60W CO2. This surgical laser has an articulated arm with seven elbows to allow the surgeon to guide the laser beam. The laser is designed for Indian conditions and can withstand the extreme ambient. Twelve such lasers have already been supplied to hospitals in India, in cities extending from Delhi to Thiruvananthapuram and from Mumbai to Calcutta. 

Industrial Application

CO2 lasers also find applications in industries. However, for cutting, welding and surface treatment of metals, lasers of much higher power are required. CAT has also developed a fast glow high power CO2 laser capable of giving up to 5 KW power continuously. This laser can cut steel sheets more than one cm. thick with ease. Workstations to handle jobs have also been developed at CAT.

The high power CO2 laser has been used for several material processing applications such as cutting, welding and surface treatment. Laser welding is particularly suitable for welding dissimilar metals. CAT is collaborating with many academic institutions to study laser material processing.

Some time ago CAT scientists were approached by the Bharat Heavy Electricals Ltd. (BHEL), which makes large steam turbines for power stations, to explore the possibility of repairing eroded turbine blades by laser alloying. BHEL imports these turbine blades made of very hard nickel superalloy at huge cost and repair of eroded blades would result in considerable savings to it in foreign exchange. Using the 4 KW high power CO2 laser, CAT scientists have successfully cladded an even harder material on the blades. Similarly, a technique was developed to improve ceramic coating to turbine blades by laser glazing. 

Medical Applications

CAT has also been developing lasers for surgery. It has promoted research in this area in various hospitals through a National Laser Programme. Apart from the surgical CO2 laser, CAT has developed nitrogen laser for medical use. Nitrogen laser has been found useful for the treatment of tuberculosis. Many patients of TB develop cavities in their lungs which become the breeding ground of the TB bacillus.

The treatment consists of inserting a needle from the back of the patient into the cavity and then irradiating the cavity with the nitrogen laser beam which is transmitted through an optical fibre inserted through the needle into the cavity. CAT has funded a project under the National Laser Programme at a hospital in Indore and has supplied a nitrogen laser coupled with optical fibre giving 3 megawatts of average power. The hospital has treated more than 200 patients of TB who had developed cavities in their lungs and who were on drugs for several years but had become resistant to drugs. With the nitrogen laser treatment, a large percentage of patients showed complete recovery within 2-3 months.

The hospital extended this procedure to other areas where drug resistance was encountered, for example, burn wounds infected with drug resistant Pseudomonas. Exposure of the burn wounds to nitrogen laser for about 10 minutes every day for 5 days resulted in complete healing of the wounds.

CAT also has a programme on the use of lasers in medical diagnosis. It has taken up development of analytical instruments based on lasers. One such system is a laser fluorometer for detection of low concentration of uranium in water samples. This instrument uses a nitrogen laser to excite fluorescence in uranium source. The intensity of this fluorescence is a direct indication of the concentration of uranium in water. To suppress fluorescence from other substances generally present in water, optical and electronic filtering is used. This instrument can measure uranium concentration as low as 0.2 ppb (parts per billion).

Several such instruments are in regular use in various units of the Department of Atomic Energy which handles uranium, to check the concentration of uranium in water. The Atomic Minerals Division which explores uranium ores also uses this instrument for preliminary exploration. Scientists of Atomic Minerals Division collect water samples from deep wells and look for uranium. Recently the Department of Atomic Energy donated two such instruments to the Seibersdorf Laboratory of International Atomic Energy Agency (IAEA), Vienna.-(PIB)

Dr.D.D.Bhawalkar

Working at Centre for Advanced Technology, Indore

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