Rajiva Bhatnagar - Academia.edu (original) (raw)
Papers by Rajiva Bhatnagar
International Journal of Innovative Science and Research Technology, 2023
The Indus Valley Civilisation (IVC) was unique amongst the contemporaneous civilisations of the b... more The Indus Valley Civilisation (IVC) was unique amongst the contemporaneous civilisations of the bronze Age because of its geographical extent, technological advancements, an organised civic society, well-planned cities, unprecedented standardization of construction materials and methods, weights and measures, manufacturing, and bristling trade as far away as Mesopotamia, Egypt, and Afrika. The rise of Indus Civilisation (8 th to 4 th millennium BCE) culminated in its mature phase that lasted from 2600 BCE to 1900 BCE and by 1300 BCE its cities were abandoned. The reasons advanced for this decline include, climatic changes, rivers changing courses, recurring floods, and loss of international trade etc. The possibility of ideological conflicts, though indicated by Hussain has not been seriously investigated [1]. In this paper, an attempt is made to establish if ideological conflict could indeed have led to the collapse of this civilisation.
ABSTRACT A copper vapour laser is a gas discharge laser that requires fast, high-voltage, high-re... more ABSTRACT A copper vapour laser is a gas discharge laser that requires fast, high-voltage, high-repetition-rate excitation pulses. In this paper, energy deposition studies in a typical copper vapour laser are reported under various pulse excitation schemes and under different operating conditions of the laser. The energy deposited in the laser tube is calculated by processing the measured voltage and current waveforms on the laser tube. This method has advantages over the calorimetric measurement method because it gives time-resolved energy deposition in the laser tube during the excitation pulse. Three different charge transfer circuits are used for pulse excitation: one is based on a thyratron switch, the second one on a magnetic pulse compressor switch and the third one on an insulated-gate bipolar transistor assisted by a magnetic pulse compressor. From studies of these circuits, it is found that the conventional thyratron-based capacitor-to-capacitor charge transfer circuit has the highest overall efficiency of energy deposition but it has the lowest energy deposition efficiency in the initial 100 ns of the pulse.
Optics Communications, 1993
... laser SK Dixit, JK Mittal, B. Singh, P. Saxena and R. Bhatnagar Laser Programme, CentreforAdv... more ... laser SK Dixit, JK Mittal, B. Singh, P. Saxena and R. Bhatnagar Laser Programme, CentreforAdvanced Technology, Indore452013, India Received 13 ... Another aperture of appropriate size, placed close to the concave mirror clips the wings of the Airy intensity distribution and ...
Optics Communications, 1991
... Optics 28 (1989) 2047. [6] JK Mittal, PK bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J... more ... Optics 28 (1989) 2047. [6] JK Mittal, PK bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J. Phys. E: Sci. ... JK Mittal, PK bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J. Phys. E: Sci. Instrum. 21 (1988), p. 388. B. Singh, SK Dixit, R. Bhatnagar and JK Mittal, J. Appl. Phys. ...
Review of Scientific Instruments, 1993
... B. Singh, SV Nakhe, JK Mittal, SK Dixit, HS Vora, and R. Bhatnagar Laser Programme, Centre fo... more ... B. Singh, SV Nakhe, JK Mittal, SK Dixit, HS Vora, and R. Bhatnagar Laser Programme, Centre for Advanced Technology, Indore 452013, India (Received 14 September 1992; accepted for publication 9 October 1992) ... JK Mittal, PK Bhadani, B. Singh, L. Abhinandan, and R ...
Review of Scientific Instruments, 1984
... described. The oven made of alumina tube, tungsten heater, and graphite felt insulation, take... more ... described. The oven made of alumina tube, tungsten heater, and graphite felt insulation, takes about 45 min at 1,5-kW heater input power to reach temperatures in excess of 1500 °C. Its use with a copper vapor laser is demonstrated. ...
Journal of Physics E: Scientific Instruments, 1988
... Printed in the UK Design and performance of a 20 watt copper vapour laser JK Mittal, PK Bhada... more ... Printed in the UK Design and performance of a 20 watt copper vapour laser JK Mittal, PK Bhadani, B Singh, L Abhinandan and R Bhatnagar Centre for Advanced Technology, PO Box 10, Indore 452 004, India Received 22 April 1987, in final form 9 September 1987 Abstract. ...
Review of Scientific Instruments, 2004
The paper presents the design and performance of a transversely pumped, narrow bandwidth, high wa... more The paper presents the design and performance of a transversely pumped, narrow bandwidth, high wavelength stability tunable dye laser that neither uses low expansion coefficient materials for construction nor incorporates any active control on the wavelength or the dye solution and environmental temperature as generally used in such lasers. The scheme essentially involves designing the mechanical assembly in such a
Pramana, 1979
The paper discusses the performance characteristics of a Nd: glass laser system designed for lase... more The paper discusses the performance characteristics of a Nd: glass laser system designed for laser produced plasma studies. It consists of aQ-switched oscillator followed by two amplifier stages. The output behaviour of the oscillator, i.e. laser pulse duration, peak power and optimum coupling, has been studied and is in good agreement with theory. Gain characteristics of amplifiers were obtained as
Optics Letters, 1990
Copper-vapor lasers (CVL's) with positive-branch unstable resonators have been used exten... more Copper-vapor lasers (CVL's) with positive-branch unstable resonators have been used extensively for reducing output-beam divergence. In contrast, the negative-branch unstable resonator has not been applied to CVL's. Here we study the performance of a negative-branch unstable-resonator CVL with various magnifications. A divergence of approximately 3.25 times the diffraction limit was obtained.
Optics Communications, 1991
... Phys., to be published. [ 12 ] JK Mittal, PK Bhadani, B. Singh, L. Abhinandan and R. Bhatnaga... more ... Phys., to be published. [ 12 ] JK Mittal, PK Bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J. Phys. E: Sci. ... [12]JK Mittal, PK Bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J. Phys. E: Sci. Instrum. 21 (1988), p. 388. [13]RS Hargrove, R. Grove and T. Kan, IEEE J. Quant. ...
Optics Communications, 2000
Single pulse time resolved studies on the development of dye laser characteristics are conspicuou... more Single pulse time resolved studies on the development of dye laser characteristics are conspicuous by their absence. In this paper we report, for the first time, studies on the temporal variation of bandwidth and divergence of a transverse pumped, prism beam expander grazing incidence grating dye laser within a single pulse. It is shown that the characteristics of the dye laser pulse depend on the divergence of the pump beam and its temporal variation. q
Optics Communications, 1998
ABSTRACT
Optics Communications, 1998
The paper presents a novel resonator scheme consisting of two coupled dye laser resonators to obt... more The paper presents a novel resonator scheme consisting of two coupled dye laser resonators to obtain independently tunable and collinear two-wavelengths having adjustable delay between them. A single grating is used to provide dispersion and coupling. With 510.6 and 578.2 nm of copper vapor laser to pump Rhodamine 6G and Sulforhodamine B dyes respectively the collinear outputs could be tuned
Optics Communications, 1992
In a confocal positive branch unstable resonator, collimated output is extracted by placing a scr... more In a confocal positive branch unstable resonator, collimated output is extracted by placing a scraper mirror near the shorter focal length mirror. The output from the other end is generally not preferred because it has geometrical divergence in addition to the natural divergence. Recent experiments with noncavity lasers have indicated that asymmetry in the emission characteristics in the two counter directions could exist because of the fact that the radiation sees different radii of curvature mirrors during the first transit. Such behavior is particularly expected in high gain short inversion lifetime lasers like copper vapor lasers. In this paper, spatial and temporal characteristics of the output from the two ends ofa PBUR CVL are studied. The results establish that significant asymmetry in the divergence of the two outputs exists. The temporal evolution of the divergence of the two outputs are different. The uncollimated output has better divergence compared to the collimated output.
Optics Communications, 1997
... Acknowledgements The authors gratefully wish to acknowledge the support of all members of the... more ... Acknowledgements The authors gratefully wish to acknowledge the support of all members of the group in maintaining and operating the laser. References [I] SK Dixit, JK Mittal, B. Singh, P. Saxena and R. Bhatnagar, Optics Comm. ... L. Abhinandan and R. Bhamagar, J. Phys. ...
Optics Communications, 1995
Collinear operation at multiple wavelengths in dye lasers is difficult to maintain because of gai... more Collinear operation at multiple wavelengths in dye lasers is difficult to maintain because of gain competition between the lasing wavelengths. Also, it is difficult to ensure the same linewidth for all the lasing wavelengths due to differences in the resonator characteristics. In this paper a new resonator geometry, using a combination of two gratings, is proposed to obtain collinear, tunable,
International Journal of Innovative Science and Research Technology, 2023
The Indus Valley Civilisation (IVC) was unique amongst the contemporaneous civilisations of the b... more The Indus Valley Civilisation (IVC) was unique amongst the contemporaneous civilisations of the bronze Age because of its geographical extent, technological advancements, an organised civic society, well-planned cities, unprecedented standardization of construction materials and methods, weights and measures, manufacturing, and bristling trade as far away as Mesopotamia, Egypt, and Afrika. The rise of Indus Civilisation (8 th to 4 th millennium BCE) culminated in its mature phase that lasted from 2600 BCE to 1900 BCE and by 1300 BCE its cities were abandoned. The reasons advanced for this decline include, climatic changes, rivers changing courses, recurring floods, and loss of international trade etc. The possibility of ideological conflicts, though indicated by Hussain has not been seriously investigated [1]. In this paper, an attempt is made to establish if ideological conflict could indeed have led to the collapse of this civilisation.
ABSTRACT A copper vapour laser is a gas discharge laser that requires fast, high-voltage, high-re... more ABSTRACT A copper vapour laser is a gas discharge laser that requires fast, high-voltage, high-repetition-rate excitation pulses. In this paper, energy deposition studies in a typical copper vapour laser are reported under various pulse excitation schemes and under different operating conditions of the laser. The energy deposited in the laser tube is calculated by processing the measured voltage and current waveforms on the laser tube. This method has advantages over the calorimetric measurement method because it gives time-resolved energy deposition in the laser tube during the excitation pulse. Three different charge transfer circuits are used for pulse excitation: one is based on a thyratron switch, the second one on a magnetic pulse compressor switch and the third one on an insulated-gate bipolar transistor assisted by a magnetic pulse compressor. From studies of these circuits, it is found that the conventional thyratron-based capacitor-to-capacitor charge transfer circuit has the highest overall efficiency of energy deposition but it has the lowest energy deposition efficiency in the initial 100 ns of the pulse.
Optics Communications, 1993
... laser SK Dixit, JK Mittal, B. Singh, P. Saxena and R. Bhatnagar Laser Programme, CentreforAdv... more ... laser SK Dixit, JK Mittal, B. Singh, P. Saxena and R. Bhatnagar Laser Programme, CentreforAdvanced Technology, Indore452013, India Received 13 ... Another aperture of appropriate size, placed close to the concave mirror clips the wings of the Airy intensity distribution and ...
Optics Communications, 1991
... Optics 28 (1989) 2047. [6] JK Mittal, PK bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J... more ... Optics 28 (1989) 2047. [6] JK Mittal, PK bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J. Phys. E: Sci. ... JK Mittal, PK bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J. Phys. E: Sci. Instrum. 21 (1988), p. 388. B. Singh, SK Dixit, R. Bhatnagar and JK Mittal, J. Appl. Phys. ...
Review of Scientific Instruments, 1993
... B. Singh, SV Nakhe, JK Mittal, SK Dixit, HS Vora, and R. Bhatnagar Laser Programme, Centre fo... more ... B. Singh, SV Nakhe, JK Mittal, SK Dixit, HS Vora, and R. Bhatnagar Laser Programme, Centre for Advanced Technology, Indore 452013, India (Received 14 September 1992; accepted for publication 9 October 1992) ... JK Mittal, PK Bhadani, B. Singh, L. Abhinandan, and R ...
Review of Scientific Instruments, 1984
... described. The oven made of alumina tube, tungsten heater, and graphite felt insulation, take... more ... described. The oven made of alumina tube, tungsten heater, and graphite felt insulation, takes about 45 min at 1,5-kW heater input power to reach temperatures in excess of 1500 °C. Its use with a copper vapor laser is demonstrated. ...
Journal of Physics E: Scientific Instruments, 1988
... Printed in the UK Design and performance of a 20 watt copper vapour laser JK Mittal, PK Bhada... more ... Printed in the UK Design and performance of a 20 watt copper vapour laser JK Mittal, PK Bhadani, B Singh, L Abhinandan and R Bhatnagar Centre for Advanced Technology, PO Box 10, Indore 452 004, India Received 22 April 1987, in final form 9 September 1987 Abstract. ...
Review of Scientific Instruments, 2004
The paper presents the design and performance of a transversely pumped, narrow bandwidth, high wa... more The paper presents the design and performance of a transversely pumped, narrow bandwidth, high wavelength stability tunable dye laser that neither uses low expansion coefficient materials for construction nor incorporates any active control on the wavelength or the dye solution and environmental temperature as generally used in such lasers. The scheme essentially involves designing the mechanical assembly in such a
Pramana, 1979
The paper discusses the performance characteristics of a Nd: glass laser system designed for lase... more The paper discusses the performance characteristics of a Nd: glass laser system designed for laser produced plasma studies. It consists of aQ-switched oscillator followed by two amplifier stages. The output behaviour of the oscillator, i.e. laser pulse duration, peak power and optimum coupling, has been studied and is in good agreement with theory. Gain characteristics of amplifiers were obtained as
Optics Letters, 1990
Copper-vapor lasers (CVL's) with positive-branch unstable resonators have been used exten... more Copper-vapor lasers (CVL's) with positive-branch unstable resonators have been used extensively for reducing output-beam divergence. In contrast, the negative-branch unstable resonator has not been applied to CVL's. Here we study the performance of a negative-branch unstable-resonator CVL with various magnifications. A divergence of approximately 3.25 times the diffraction limit was obtained.
Optics Communications, 1991
... Phys., to be published. [ 12 ] JK Mittal, PK Bhadani, B. Singh, L. Abhinandan and R. Bhatnaga... more ... Phys., to be published. [ 12 ] JK Mittal, PK Bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J. Phys. E: Sci. ... [12]JK Mittal, PK Bhadani, B. Singh, L. Abhinandan and R. Bhatnagar, J. Phys. E: Sci. Instrum. 21 (1988), p. 388. [13]RS Hargrove, R. Grove and T. Kan, IEEE J. Quant. ...
Optics Communications, 2000
Single pulse time resolved studies on the development of dye laser characteristics are conspicuou... more Single pulse time resolved studies on the development of dye laser characteristics are conspicuous by their absence. In this paper we report, for the first time, studies on the temporal variation of bandwidth and divergence of a transverse pumped, prism beam expander grazing incidence grating dye laser within a single pulse. It is shown that the characteristics of the dye laser pulse depend on the divergence of the pump beam and its temporal variation. q
Optics Communications, 1998
ABSTRACT
Optics Communications, 1998
The paper presents a novel resonator scheme consisting of two coupled dye laser resonators to obt... more The paper presents a novel resonator scheme consisting of two coupled dye laser resonators to obtain independently tunable and collinear two-wavelengths having adjustable delay between them. A single grating is used to provide dispersion and coupling. With 510.6 and 578.2 nm of copper vapor laser to pump Rhodamine 6G and Sulforhodamine B dyes respectively the collinear outputs could be tuned
Optics Communications, 1992
In a confocal positive branch unstable resonator, collimated output is extracted by placing a scr... more In a confocal positive branch unstable resonator, collimated output is extracted by placing a scraper mirror near the shorter focal length mirror. The output from the other end is generally not preferred because it has geometrical divergence in addition to the natural divergence. Recent experiments with noncavity lasers have indicated that asymmetry in the emission characteristics in the two counter directions could exist because of the fact that the radiation sees different radii of curvature mirrors during the first transit. Such behavior is particularly expected in high gain short inversion lifetime lasers like copper vapor lasers. In this paper, spatial and temporal characteristics of the output from the two ends ofa PBUR CVL are studied. The results establish that significant asymmetry in the divergence of the two outputs exists. The temporal evolution of the divergence of the two outputs are different. The uncollimated output has better divergence compared to the collimated output.
Optics Communications, 1997
... Acknowledgements The authors gratefully wish to acknowledge the support of all members of the... more ... Acknowledgements The authors gratefully wish to acknowledge the support of all members of the group in maintaining and operating the laser. References [I] SK Dixit, JK Mittal, B. Singh, P. Saxena and R. Bhatnagar, Optics Comm. ... L. Abhinandan and R. Bhamagar, J. Phys. ...
Optics Communications, 1995
Collinear operation at multiple wavelengths in dye lasers is difficult to maintain because of gai... more Collinear operation at multiple wavelengths in dye lasers is difficult to maintain because of gain competition between the lasing wavelengths. Also, it is difficult to ensure the same linewidth for all the lasing wavelengths due to differences in the resonator characteristics. In this paper a new resonator geometry, using a combination of two gratings, is proposed to obtain collinear, tunable,