Solid State Laser Electronics Section

Electronics Laboratory

Research and Development Activities

1.Power Supply, TEC based temperature controllers, control electronics and programmable user interface for Green laser photo coagulator

Green Laser Photo Coagulator System (GLPU-II) has been developed under MoU between Aurolab, Madurai and RRCAT with a view to develop an indigenous laser photo coagulator unit at low cost so that the diabetic retinopathy becomes affordable for poor diabetic patients. Laser diode power supply, temperature controllers and TEC drivers for diode and crystals, microcontroller based control and programmable user-interface with touch panel control have been developed. These sub-systems of electronics have been integrated with the laser system of the GLPU. The integrated system has been thoroughly tested and delivered to Aurolab, Madurai for clinical trials on human patients. The clinical trials have also been carried out successfully by doctors at Aravind Eye Care Hospital, Madurai.

Green Laser Photo Coagulator Unit
Green Laser Photo Coagulator Unit – II (GLPU-II) with touch panel control

2.Power Supplies for Arc-lamp-pumped CW Solid State Laser Systems:

(a) Power Supply for CW Nd:YAG Laser for Laser Cladding Applications commissioned at IGCAR

A power supply for 500W CW Nd:YAG laser system with programmable user interface and front panel has been developed and commissioned at IGCAR for laser cladding applications. The power supply incorporates buck converter based dc current source, booster source, trigger source and control circuitry. It can deliver an adjustable output current in the range of 10 - 50A with a compliance voltage of 180V.

(b) Power Supply for CW Nd:YAG Laser for Laser Material Processing Applications commissioned at BARC

A 20kW power supply for dual arc-lamp pumped 800W CW Nd:YAG laser system with programmable user interface has been developed and commissioned at MSD, Material Group, BARC along with the laser system for laser material processing applications including laser rapid manufacturing.

3.Power Supplies for flash-lamp-pumped Quasi-CW Solid State Laser Systems:

(a)Power supply for Laser Welding System for Cardiac Pacemaker Shells

A power supply for flash-lamp-pumped Nd:YAG laser based welding system for Cardiac Pacemaker shells has been developed and commissioned along with the Nd:YAG laser system to a public limited company. The system is being used for manufacturing of cardiac pacemakers indigenously.

(b) Power Supply for Industrial Nd:YAG laser for Laser Material Processing Applications

A power supply for flash-lamp-pumped Nd:YAG laser based material processing system has been developed and commissioned at Industrial Laser Lab, SSLD and is being used for various laser material processing applications for different R & D units of DAE and NPCIL. The pulse power source of the power supply system can deliver an average output power up to 5kW with peak output power up to 100kW. The output load current is adjustable from 100 to 300A, pulse width from 2 to 20 ms and pulse repetition rate up to 100PPS.

(c) Power supplies for 500W and 1kW Nd:YAG laser based Laser Welding Systems

A power supply for dual flash lamp pumped 500W Industrial Nd:YAG laser system for welding of niobium and copper components has been developed and commissioned at Cryo Engineering and Cryo Module Development Section. This power supply can deliver a total average power of 10kW to both the lamp loads with peak power of 100kW to each lamp. The flash lamp current is adjustable from 100A to 300A, pulse width from 2ms to 40ms and pulse repetition rates up to 100 PPS.

A power supply for quad flash lamp pumped 1kW Industrial Nd:YAG laser system for welding of stainless steel and copper components including nine cell copper RF tuner cavity has been developed and commissioned at SSLD.

4.Power Supplies for Flash-lamp-pumped Pulsed Solid State lasers:

(a) Power supplies for Pulsed Nd:YAG Laser for thermal diffusivity experiments at IGCAR and BARC

A power supply for pulsed Nd:YAG laser system has been developed which incorporates a PFN charging source, simmer current source, trigger source and control circuitry. It can charge a PFN capacitance of 1500 µF to an adjustable voltage in the range from 500 to 1200 V at repetition rates up to 1 PPS. The stored energy in the PFN can be delivered to the flash lamp in 1 ms to get a laser pulse of 18 J. Two such power supply units along with the laser systems have been tested and commissioned at MCD, IGCAR and FCD, BARC for thermal diffusivity experiments.

(b) Power supply for Dual Flash-Lamp Pumped Pulsed Nd:YAG Laser for laser cleaning and evaporation cutting applications

A power supply incorporating two pulsed power sources along with simmer and trigger source is designed and developed for powering dual flash lamp pumped pulsed Nd:YAG laser operating in short free-running mode for laser cleaning and evaporation cutting applications. Pulsed power sources operate in synchronism with each other and each consists of constant current PFN charging power supply based on zero-voltage switching LCL-T resonant converter operating at switching frequency of 100 kHz. The PFN charging power supply can charge a capacitance of 40µF to an adjustable voltage in the range from 300 to 1200 V at repetition rates up to 20 PPS. The peak amplitude of PFN discharge current pulse is 900 A with pulse width of 55 µs and total pump energy per pulse is 55 J. The power supply unit has been commissioned at SSLD and used for laser cleaning applications and evaporation cutting of SG tubes. .

Power supply for Dual Flash-Lamp Pumped Pulsed Nd:YAG Laser for laser cleaning and evaporation cutting applications

5.Power Supply for indigenization of Laser Radiator of T-90 tank for OLF

A battery driven power supply for arc lamp pumped CW solid state laser has been designed, developed and installed at the solid state laser lab, SSLD for development and optimization of laser to indigenize laser radiator for T-90 tank for OLF. It incorporates start-up circuits viz. 10kV, 8µs trigger unit and 1 kV booster unit, besides the main current source of 1.2 kW for arc lamp load powered from a battery bank at 27V +3V -5V. 1200W & 1400 W arc lamp power supplies. Various operational modes have also been incorporated to facilitate development, optimization and rigorous testing of the laser unit.

Power Supply for indigenization of Laser Radiator of T-90 tank for OLF

6.Laser diode Power Supply

The laser diode driver can deliver CW or pulsed current adjustable from 1 to 40A with a compliance voltage of 3.3 V. The driver is realized with high frequency converter with switching frequency of 250 kHz. The line and load regulation of output current is better than 0.2% with a ripple of 0.2%. The output of drivers can be connected in parallel or series to augment output current capacity and voltage as it is based on peak current control and output is isolated from common as well as ac mains.

Laser diode  Power Supply

7.TEC based water chiller unit

A thermo-electric-cooler (TEC) based Water chiller unit with cooling capacity of 50 W provides heating and cooling mode of operation for controlling temperature of water. The temperature of the chiller-water can be set in the range of 18 to 22 °C with a resolution of 0.1°C and controlled within ± 0.1°C of the set value. It incorporates microcontroller based user interface to set the temperature and also various safety interlocks with suitable alarms. The Water chiller unit has been commissioned at Laser Plasma Lab for cooling of Ti-Sa laser setup.

TEC based water chiller unit

8.CO2 Laser Power supply for remote heating applications at VSSC, ISRO

Power supply and control electronics for 100W CW CO2 laser has been developed and commissioned at VSSC, ISRO, Trivandrum along with the laser system for remote heating applications.

9.SMPS for 40W CO2 Laser Power supply

A HV power supply for 40 W sealed-off CO2 laser which is a current source with output current adjustable from 0 to 25 mA with output voltage limited to 18kV has been developed and commissioned at Fibre Optics Lab, RRCAT for marking long period gratings and studies on development of line tunable laser for experiments on photo-acoustic spectroscopy. The converter has an uncontrolled ac-dc stage at input followed by a dc-dc stage based on LCC resonant converter in closed loop control and operated above resonance from 120 to 240 kHz to vary the output current through laser discharge tube of 1 meter length.

SMPS for 40W CO2 Laser Power supply

10.Ballast-less simmer power supply for flash-lamp-pumped solid-state lasers

A ballast-less simmer current source of 1 A with no-load voltage of 1400 V has been designed, developed and tested on actual flash lamp load along with the main pulse power source delivering pulsed power to the flash lamp. It can deliver stable simmer current adjustable from 0.3 to 1 A without using any ballast, thus eliminating the energy loss in resistive ballast and improving efficiency of the system. The power supply uses resonant converter operating at switching frequency in the range of 80 to 100 kHz.

11.Laser diode power supply and control circuits for High Resolution Spectroscopy experiments

A power supply for 50 mW diode laser and a thermo-electric-cooler (TEC) based temperature controller to maintain the temperature of the laser diode mounting block in the range of 18 to 30 °C within +/-0.1 °C has been developed. Modulation facility in the driver current by an adjustable ramp signal to improve the stability of the system is also provided. A PZT driver for a frequency range of 0.1 to 100 Hz with an output voltage in the range of +/- 20 V has been developed which can drive PZT by triangular and saw tooth waveforms with an adjustable dc level shift.

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