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(L&PTD)
Dye Laser
| A prototype single-longitudinal mode (SLM) dye laser, consisting of a rugged metal dye-cell with replaceable quartz windows, a holographic grating in a Littrow configuration, and an output coupler fixed onto a piezo actuator has been developed. The laser cavity length of 30mm offers a large axial mode separation of 0.17cm-1 |
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Single-longitudanal al mode (SLM) dye laser
An indigenous technology for synthesis and production of high purity laser dye, Rhodamine 6G and high power, high repetition rate dye lasers with water-based solvents have been successfully developed. This will lead to substantial cost benefits on laser dyes. Superior thermal characteristics, better stability, hazard-free operation, easy disposal and handling are some potential advantages of these water-based solvents compared to ethanol.
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Laser-Atom Interaction
Laser-atom interaction processes are often strongly influenced by non-linear response of atoms to incident light intensity. A facile experimental technique, referred to as the Z-scan technique, has been developed for determining this optical non-linearity.
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Optical Parametric Oscillators
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Optical Parametric Oscillators, which are solid-state laser beam sources with widely tunable output wavelength have been developed and used for trace detection of uranium. Use of wavelength tunable radiation substantially improves the sensitivity and selectivity in ultra trace detection of several elements, including uranium, in process streams and effluents.
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A pulsed nanosecond Bariumborate (BBO) Optical Parametric Oscillator, continuously tunable in the visible and near infrared region, has been demonstrated.
The OPO cavity consists of a BBO crystal cut at 30 deg for Type-I phase matching placed inside a 30mm long cavity with plane reflectors. The threshold energy was 5-8mJ over the total tuning range from 430nm to 2.2 microns. A total energy conversion efficiency of 32% was achieved.
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Gas Lasers
| An electron beam pumped Transversely Excited Atmospheric Carbon Dioxide (TEA-CO2) laser has been developed. Helium free operation of a TEA CO2 laser has been achieved in a variety of systems including a wide range of the active volume (about 1 cc to ~ 150 cc), different electrode geometrical configuration, etc. The repetitive operation has been realized without the expensive gas recirculatory loop consisting of the heat exchanger and the catalytic
reconvertor. |
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One of the features of this laser is that, by dispensing with the switch in the main discharge loop and simplifying the electrical excitation
circuit, a higher electro-optic efficiency and easy maneuverability of the temporal shape of the pulse is obtained. The system is capable of delivering up to 75 J of energy per pulse at an electro-optic efficiency of ~26%. The experimental setup is shown aside. Our success in achieving closure of parallel UV emitting spark channels without over-voltage opens up the possibility of repetitive operation of such switchless lasers.
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Laser Photochemistry
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A prototype facility for macroscopic production of carbon isotopes is getting
raedy. Photochemical reactor (PCR) has a modular structure consisting of three units each having a laser interaction chamber
(LIC) and a gas blower chamber (GBC). |
A pair of high reflectivity (( 98.5 %) copper mirrors mounted inside LIC in multi-pass, re-focusing Herriott Configuration for efficient photon utilization. A total of 13 passes have been obtained after careful alignment with 35 mm dia process CO2
laser beam at 10 Hz rep rate. Each GBC has a centrifugal blower, which can be driven at desired speeds using a variable frequency control unit. Flow velocity, monitored at different locations in
LIC, can be varied in the range of 3 - 5 m / sec for various blower speeds. User interactive software has been developed to obtain three dimensional view of multipass refocusing laser beam in Herriott cavity by modeling the interaction of rays with the mirrors.
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