Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, Sep 26, 2017
Aspheric optics is widely used for many optical applications due to their advantages, that is, li... more Aspheric optics is widely used for many optical applications due to their advantages, that is, light weight, costeffectiveness and efficiency. There are many fabrication challenges which affect the quality of aspheric optics used for infrared-based applications. Diamond turning is one of the most suitable techniques for fabrication of infrared aspheric lens with high profile accuracies, due to its deterministic approach. However, for optics with large sag value, multiple machining cycles are required to make the best fit surface. Repeated machining cycles result in generation of inherent stresses leading to subsurface deformation and poor quality. In this study, hybrid approach of grinding and machining is proposed for fabrication of silicon infrared optics in large volume. The proposed approach results in reduced fabrication time and subsurface deformation with improved surface quality and tool life. The profile accuracy after compensation of profile error (P t ) is 0.21 mm and surface roughness (R a ) 10.5 nm is achieved.
Indian Journal of Pure & Applied Physics, Oct 1, 2019
Performing target detection/identification task using only visible spectrum information becomes e... more Performing target detection/identification task using only visible spectrum information becomes extremely difficult during low ambient light conditions. Visible spectrum information consists of information available in the range of 400-700 nm wavelength. However, infrared spectrum carries information beyond 800 nm. To overcome the difficulty of target detection by human operator during the task of surveillance, fusion of visible and infrared spectral image information has been proposed. The image fusion has been performed using multi resolution transform based curvelet technique. The use of curvelet transform has been done because of its high directional sensitivity and reconstruction quality. Curvelet transform has been used to decompose source images to obtain coefficients at coarse, intermediate and fine scale. These coefficients have been fused as per respective decomposition level, followed by reconstruction of fused image using inverse curvelet transform. Bispectral fused image inherits scene information as well as target information both from visible and infrared spectrum images respectively. The proposed image fusion output images are visually and statistically compared with other fusion method outputs. The fused image obtained using proposed fusion method in comparison to other fusion results show clear background details, high target distinctiveness, better reconstruction and lesser clutter.
The need for freeform surfaces are widely recognized in the optical, aerospace, biomedical, and a... more The need for freeform surfaces are widely recognized in the optical, aerospace, biomedical, and automotive industries. However, the fabrication of freeform surfaces is very difficult and expensive because of the involvement of advanced, multiaxis, dedicated machining processes. In many applications, the machining surface needs further polishing to reduce the surface roughness. The main aim of this work is to investigate the flexible pad polishing process for the finishing of the freeform surface. To achieve this, a flexible pad polishing setup is developed in two-axis configuration that can be integrated with a diamond turning machine or any other computer numerical control (CNC) machine and capable to polish the conventional rotationally symmetric surfaces as well as freeform surfaces. The polishing parameters for the developed polishing head are optimized for the nano-finishing of the freeform mold surface of Stavax ESR steel. The effectiveness of the current polishing setup is demonstrated by measuring the improvement in surface roughness height and profile. Test results reveal that the improvement on the freeform surface is significant, that is, surface roughness (R a ) reduces from 220 nm to 25 nm while keeping the profile within the desired tolerance.
Journal of Intelligent Material Systems and Structures, Apr 24, 2018
Silicon mirrors are essential for guiding the X-ray beam and focusing it to a specific location. ... more Silicon mirrors are essential for guiding the X-ray beam and focusing it to a specific location. These mirrors using total internal reflection require super smooth surface finish due to small wavelength of X-ray. Magnetorheological finishing is a computer-controlled technique used in the production of high-quality optical lenses. This process utilizes polishing slurries based on magnetorheological fluids, whose viscosity changes with the change in magnetic field. In this work, polishing potential of silicon mirrors by magnetorheological finishing process is examined to achieve nanometric surface finish for X-ray applications. The individual effect of parameters such as magnetizing current, working gap, rotational speed on surface roughness is investigated, and optimized parameters are identified. To investigate the physical essence underlying magnetorheological finishing process, the molecular dynamics simulations are used. Molecular dynamics simulation is used to study the atomic-scale removal mechanism of single-crystalline silicon in magnetorheological finishing process and attention is paid to study the effect of gap between the tool and the workpiece on surface quality. The outcome is promising and the final surface roughness achieved is as low as 6.4 nm. The surface quality is analyzed in terms of arithmetic roughness, power spectral density, and image analysis of scanning electron microscopy for uniform evaluation.
2019 International Conference on Vision Towards Emerging Trends in Communication and Networking (ViTECoN), 2019
Modern era technologies are adopting miniaturization process and procedures for system automation... more Modern era technologies are adopting miniaturization process and procedures for system automation wherein electronics and electrical plays a vital role for its faithful performance. Miniaturized circuits and systems need efficient heat dissipation for its reliable performance in varying ambient temperature conditions. The proposed technique of thermal management would be used in compact avionics cockpit display system to drive the mixed signal conditioning and processing of multisensory data of an aircraft. Simulation has been carried out on a DC-DC converter for efficient heat dissipation by fluid (air, water) convective technique. The proposed heat dissipation technique with condenser would be used for varying ambient temperature conditions as per thermal MIL-Standards 810E.Various cooling techniques for circuits and systems have been discussed in this paper. Simulation results have been discussed for effectiveness of thermal dissipation from the converter. Most effective cooling technique is analyzed with condenser and water as coolant that brings down temperature from 471K to 327K at an ambient temperature of 343K. Also, the proposed thermal management design would be tested with nanofluids.
Lens distortion estimation and correction has been an active research area for decades and contin... more Lens distortion estimation and correction has been an active research area for decades and continues to intrigue scientists even today. With increasing usage of low-cost wide-angle lenses for commercial applications, this demand has increased even more as these lenses have relatively larger distortions. It is thus required to devise mechanisms by which these errors can be removed automatically and in an effective manner. In this paper, a neural network based technique is devised to estimate radial distortion by analysing the area enclosed by synthesizing objects of known shape. The difference in the area between ideal and distorted image is used to create a model and used later to assess its efficacy on the test dataset. The proposed scheme is found to work promisingly on synthetic images and can be extended for real-time image analysis and correction in future.
2017 2nd IEEE International Conference on Recent Trends in Electronics, Information & Communication Technology (RTEICT), 2017
Nowadays low-cost wide-angle lenses are extensively used in the fields of computer vision, photog... more Nowadays low-cost wide-angle lenses are extensively used in the fields of computer vision, photogrammetry and image processing to get critical information. However, these lenses provide vast field of view at the cost of significant distortion in the images. Hence, distortion estimation and correction becomes a prerequisite in almost all the fields. A novel approach for estimation and correction of radial estimation has been proposed in this paper. The proposed idea is based on plumb line method of distortion estimation in which no specific information about the camera parameters or scene is required. Straight lines existing in the 3D space are transformed to curves in the captured image. The proposed method determines the coefficient of distortion based on angle formed between these curves. Besides this, a detailed analysis of the effect of shape, size and position of curves is also presented.
2017 2nd IEEE International Conference on Recent Trends in Electronics, Information & Communication Technology (RTEICT), 2017
Accelerometer is one of the integral parts of a navigation system which helps in estimating motio... more Accelerometer is one of the integral parts of a navigation system which helps in estimating motion parameters of the vehicle to which it is mounted upon. With wide usage of MEMS based sensors in commercial applications such as gaming industry and mobile robotics, these sensors are required to be calibrated appropriately and in as easy manner as possible. Traditional calibration technique requires the sensor to be taken to the laboratory where it is needed to be manipulated in different orientations. However, owing to the non-availability of costly equipment, infield inertial sensor calibration has gained wide popularity in recent times. In this paper, an attempt has been made to simplify the infield calibration technique by mounting the non-calibrated unit over another calibrated sensor or vice-versa, to yield calibration parameters. The cost function arrived for this sensor to sensor calibration is solved using particle swarm optimization technique and its other variants which modifies PSO's own parameters differently is experimented. The PSO algorithm proposed here incorporates constriction factor along with time varying inertial weight for improved results than the traditional PSO scheme. The calibrated sensor reading is then compared with the data obtained from the reference calibrated sensor unit and provides the corresponding result.
Freeform optics is the next generation optics with no rotation symmetry about any axis. The fabri... more Freeform optics is the next generation optics with no rotation symmetry about any axis. The fabrication and metrology of freeform optics are not possible by conventional techniques. Due to non-symmetric nature, it is more critical to align the freeform surface during fabrication and metrology. Fabrication and metrology accuracies of the freeform optics are mainly limited due to alignment errors at all the stages of development process. In this paper, effects of alignment errors on quality of freeform optics during of fabrication and metrology are studied. It is found that alignment errors have significant contribution on quality of freeform optics development. Different types of fiducials and their importance and utilization are discussed. Further, a strategy for effective alignment of freeform optics is proposed.
Electronic nose systems have been recently in use for various applications ranging from environme... more Electronic nose systems have been recently in use for various applications ranging from environmental monitoring to biomedical applications. This paper introduces a compact electronic nose system integrating conducting polymer sensors with data acquisition, data processing and storage unit. The data acquisition system presented here is equipped with a graphical user interface (GUI) to control the acquisition parameters as well as perform analysis on obtained data. The real-time data acquisition system is capable of collecting data from an 8X8 resistive sensor array as per the parameters passed by the GUI. Finally, the paper is concluded with results and discussion obtained using the proposed electronic system. The result shows with proper classification algorithm, the system is capable of identifying various amine and alcohol groups.
Optical Design and Fabrication 2019 (Freeform, OFT), 2019
In the present study, a multilayer band pass filter using 11 layers of alternate TiO2 and SiO2 we... more In the present study, a multilayer band pass filter using 11 layers of alternate TiO2 and SiO2 were fabricated on a BK7 substrate using ion assisted electron-beam deposition technique. The filter was designed to have maximum transmission at 545 nm (Green) with adequate bandwidth to allow maximum energy transmission in the green wavelength band. The fabricated filter was found to have a bandwidth of 45 nm with a peak transmission of 91.5% at 545 nm.
Surface errors directly affect the performance of optical systems in terms of contrast and resolu... more Surface errors directly affect the performance of optical systems in terms of contrast and resolution. Surface figure errors at different surface scales are deterministically removed using controlled material removal rate (MRR) during a precision optics fabrication process. We systematically sectioned the wide range of MRR space with systematic parameters and experimentally evaluated and mapped the MRR values using a flexible membrane-polishing tool. We performed numerical analysis with a tool influence function model using a distributed MRR-based Preston’s constant evaluation approach. The analysis procedure was applied to a series of experimental data along with the tool influence function models to evaluate removal rates. In order to provide referenceable survey data without entangled information, we designed the experiments using Taguchi’s L27 orthogonal array involving five control parameters and statistically analyzed a large number of programmatic experiments. The analysis of...
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020
Thermal management of electronic systems is the utmost concern to achieve optimum efficiency unde... more Thermal management of electronic systems is the utmost concern to achieve optimum efficiency under space and weight constraints. For the optimal functioning of a system, the heat generated by the electronic components needs to be dissipated efficiently. The passive cooling technique is extensively used in electronic systems, wherein the more contact surface area of a heat source and the surroundings are utilized. This paper focuses on mathematical and simulation analysis for different types of heat sink designs for the 30 W multi-output DC–DC converter. Heat sink with inverted trapezoidal fins has resulted in efficient thermal management of the converter at its safe operating temperature of 398 K. Results show that the maximum temperature attained by the converter was 352 K which was in the safe operating zone of the converter. A comparative study of the effectiveness of heat dissipation with respect to maximum temperature attained has been discussed. Mathematical verification of Ra...
Ultra-precision machining is used to generate the high quality surfaces in terms of nano-metric s... more Ultra-precision machining is used to generate the high quality surfaces in terms of nano-metric surface finish and sub-micron profile accuracy for various engineering applications. Due to unique properties of diamond i.e. high hardness, good heat conductivity and low friction co-efficient it is most suitable tool material for ultra-precision machining. Advancements in material science and growing needs for modern applications leads to development of new materials. Silicon is one of the prominent materials used for various optical applications. However processing of silicon by machining is quite difficult due to its hard and brittle nature. Diamond tool wear is one of the major issues for ultra-precision machining which leads to increase the process cost significantly. Control of tool wear mainly depends on machining parameter selection and understanding of tool wear mechanism. Wear measurement of diamond tool is essential to understand the wear mechanism, process behavior and tool life quantification. Wear measurement of nano-metric cutting edge is one of the challenging tasks. In current study machining experiments are performed on Silicon. Tool cutting edge is analyzed by profilometric measurements at different orientations. Wear of cutting edge, rake face and flank face is measured. Measurement results are very helpful for understanding the possible reasons of wear and hence to optimize the machining conditions to minimize the tool wear.
Tantalum oxide is a widely used material as a high index layer in multilayer interference filters... more Tantalum oxide is a widely used material as a high index layer in multilayer interference filters for UV, visible and IR filters, laser mirror coatings as well as polarizer and beam splitter applications. In the present study, a single layer of Ta 2 O 5 was deposited on BK7 glass substrate using electron beam evaporation technique in an oxygenated reactive environment. The film was characterized using spectrophotometer and variable angle spectroscopic ellipsometry at angles of 65°, 70° and 75° to extract and estimate its optical constants as well as thickness. The refractive index of the film was found to be 2.0419 at 550 nm for deposition without ion assistance on a heated substrate at 250° C.
2015 Workshop on Recent Advances in Photonics (WRAP), 2015
In this framework, the Refractive elements and the Diffractive element has been combined to explo... more In this framework, the Refractive elements and the Diffractive element has been combined to explore the uniqueness of two domains into one Hybrid system. It was thus targeted to achromatize the optical system and to reduce the overall weight of the system, by incorporating lesser number of optical components to provide similar system performance using Hybrid optical design method. A 60 mm, f/2 Hybrid Petzval projection system with four components covering a 15° field of view has been presented here. The diffractive surface is introduced on the rear surface of the 3rd lens having 71 zones. The minimum zone size is approximately 2.42274 μm and the total chromatic focal shift is limited to 46.12 μm. Optimization and analysis has been performed on Zemax® and the corresponding results are shown.
Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, Sep 26, 2017
Aspheric optics is widely used for many optical applications due to their advantages, that is, li... more Aspheric optics is widely used for many optical applications due to their advantages, that is, light weight, costeffectiveness and efficiency. There are many fabrication challenges which affect the quality of aspheric optics used for infrared-based applications. Diamond turning is one of the most suitable techniques for fabrication of infrared aspheric lens with high profile accuracies, due to its deterministic approach. However, for optics with large sag value, multiple machining cycles are required to make the best fit surface. Repeated machining cycles result in generation of inherent stresses leading to subsurface deformation and poor quality. In this study, hybrid approach of grinding and machining is proposed for fabrication of silicon infrared optics in large volume. The proposed approach results in reduced fabrication time and subsurface deformation with improved surface quality and tool life. The profile accuracy after compensation of profile error (P t ) is 0.21 mm and surface roughness (R a ) 10.5 nm is achieved.
Indian Journal of Pure & Applied Physics, Oct 1, 2019
Performing target detection/identification task using only visible spectrum information becomes e... more Performing target detection/identification task using only visible spectrum information becomes extremely difficult during low ambient light conditions. Visible spectrum information consists of information available in the range of 400-700 nm wavelength. However, infrared spectrum carries information beyond 800 nm. To overcome the difficulty of target detection by human operator during the task of surveillance, fusion of visible and infrared spectral image information has been proposed. The image fusion has been performed using multi resolution transform based curvelet technique. The use of curvelet transform has been done because of its high directional sensitivity and reconstruction quality. Curvelet transform has been used to decompose source images to obtain coefficients at coarse, intermediate and fine scale. These coefficients have been fused as per respective decomposition level, followed by reconstruction of fused image using inverse curvelet transform. Bispectral fused image inherits scene information as well as target information both from visible and infrared spectrum images respectively. The proposed image fusion output images are visually and statistically compared with other fusion method outputs. The fused image obtained using proposed fusion method in comparison to other fusion results show clear background details, high target distinctiveness, better reconstruction and lesser clutter.
The need for freeform surfaces are widely recognized in the optical, aerospace, biomedical, and a... more The need for freeform surfaces are widely recognized in the optical, aerospace, biomedical, and automotive industries. However, the fabrication of freeform surfaces is very difficult and expensive because of the involvement of advanced, multiaxis, dedicated machining processes. In many applications, the machining surface needs further polishing to reduce the surface roughness. The main aim of this work is to investigate the flexible pad polishing process for the finishing of the freeform surface. To achieve this, a flexible pad polishing setup is developed in two-axis configuration that can be integrated with a diamond turning machine or any other computer numerical control (CNC) machine and capable to polish the conventional rotationally symmetric surfaces as well as freeform surfaces. The polishing parameters for the developed polishing head are optimized for the nano-finishing of the freeform mold surface of Stavax ESR steel. The effectiveness of the current polishing setup is demonstrated by measuring the improvement in surface roughness height and profile. Test results reveal that the improvement on the freeform surface is significant, that is, surface roughness (R a ) reduces from 220 nm to 25 nm while keeping the profile within the desired tolerance.
Journal of Intelligent Material Systems and Structures, Apr 24, 2018
Silicon mirrors are essential for guiding the X-ray beam and focusing it to a specific location. ... more Silicon mirrors are essential for guiding the X-ray beam and focusing it to a specific location. These mirrors using total internal reflection require super smooth surface finish due to small wavelength of X-ray. Magnetorheological finishing is a computer-controlled technique used in the production of high-quality optical lenses. This process utilizes polishing slurries based on magnetorheological fluids, whose viscosity changes with the change in magnetic field. In this work, polishing potential of silicon mirrors by magnetorheological finishing process is examined to achieve nanometric surface finish for X-ray applications. The individual effect of parameters such as magnetizing current, working gap, rotational speed on surface roughness is investigated, and optimized parameters are identified. To investigate the physical essence underlying magnetorheological finishing process, the molecular dynamics simulations are used. Molecular dynamics simulation is used to study the atomic-scale removal mechanism of single-crystalline silicon in magnetorheological finishing process and attention is paid to study the effect of gap between the tool and the workpiece on surface quality. The outcome is promising and the final surface roughness achieved is as low as 6.4 nm. The surface quality is analyzed in terms of arithmetic roughness, power spectral density, and image analysis of scanning electron microscopy for uniform evaluation.
2019 International Conference on Vision Towards Emerging Trends in Communication and Networking (ViTECoN), 2019
Modern era technologies are adopting miniaturization process and procedures for system automation... more Modern era technologies are adopting miniaturization process and procedures for system automation wherein electronics and electrical plays a vital role for its faithful performance. Miniaturized circuits and systems need efficient heat dissipation for its reliable performance in varying ambient temperature conditions. The proposed technique of thermal management would be used in compact avionics cockpit display system to drive the mixed signal conditioning and processing of multisensory data of an aircraft. Simulation has been carried out on a DC-DC converter for efficient heat dissipation by fluid (air, water) convective technique. The proposed heat dissipation technique with condenser would be used for varying ambient temperature conditions as per thermal MIL-Standards 810E.Various cooling techniques for circuits and systems have been discussed in this paper. Simulation results have been discussed for effectiveness of thermal dissipation from the converter. Most effective cooling technique is analyzed with condenser and water as coolant that brings down temperature from 471K to 327K at an ambient temperature of 343K. Also, the proposed thermal management design would be tested with nanofluids.
Lens distortion estimation and correction has been an active research area for decades and contin... more Lens distortion estimation and correction has been an active research area for decades and continues to intrigue scientists even today. With increasing usage of low-cost wide-angle lenses for commercial applications, this demand has increased even more as these lenses have relatively larger distortions. It is thus required to devise mechanisms by which these errors can be removed automatically and in an effective manner. In this paper, a neural network based technique is devised to estimate radial distortion by analysing the area enclosed by synthesizing objects of known shape. The difference in the area between ideal and distorted image is used to create a model and used later to assess its efficacy on the test dataset. The proposed scheme is found to work promisingly on synthetic images and can be extended for real-time image analysis and correction in future.
2017 2nd IEEE International Conference on Recent Trends in Electronics, Information & Communication Technology (RTEICT), 2017
Nowadays low-cost wide-angle lenses are extensively used in the fields of computer vision, photog... more Nowadays low-cost wide-angle lenses are extensively used in the fields of computer vision, photogrammetry and image processing to get critical information. However, these lenses provide vast field of view at the cost of significant distortion in the images. Hence, distortion estimation and correction becomes a prerequisite in almost all the fields. A novel approach for estimation and correction of radial estimation has been proposed in this paper. The proposed idea is based on plumb line method of distortion estimation in which no specific information about the camera parameters or scene is required. Straight lines existing in the 3D space are transformed to curves in the captured image. The proposed method determines the coefficient of distortion based on angle formed between these curves. Besides this, a detailed analysis of the effect of shape, size and position of curves is also presented.
2017 2nd IEEE International Conference on Recent Trends in Electronics, Information & Communication Technology (RTEICT), 2017
Accelerometer is one of the integral parts of a navigation system which helps in estimating motio... more Accelerometer is one of the integral parts of a navigation system which helps in estimating motion parameters of the vehicle to which it is mounted upon. With wide usage of MEMS based sensors in commercial applications such as gaming industry and mobile robotics, these sensors are required to be calibrated appropriately and in as easy manner as possible. Traditional calibration technique requires the sensor to be taken to the laboratory where it is needed to be manipulated in different orientations. However, owing to the non-availability of costly equipment, infield inertial sensor calibration has gained wide popularity in recent times. In this paper, an attempt has been made to simplify the infield calibration technique by mounting the non-calibrated unit over another calibrated sensor or vice-versa, to yield calibration parameters. The cost function arrived for this sensor to sensor calibration is solved using particle swarm optimization technique and its other variants which modifies PSO's own parameters differently is experimented. The PSO algorithm proposed here incorporates constriction factor along with time varying inertial weight for improved results than the traditional PSO scheme. The calibrated sensor reading is then compared with the data obtained from the reference calibrated sensor unit and provides the corresponding result.
Freeform optics is the next generation optics with no rotation symmetry about any axis. The fabri... more Freeform optics is the next generation optics with no rotation symmetry about any axis. The fabrication and metrology of freeform optics are not possible by conventional techniques. Due to non-symmetric nature, it is more critical to align the freeform surface during fabrication and metrology. Fabrication and metrology accuracies of the freeform optics are mainly limited due to alignment errors at all the stages of development process. In this paper, effects of alignment errors on quality of freeform optics during of fabrication and metrology are studied. It is found that alignment errors have significant contribution on quality of freeform optics development. Different types of fiducials and their importance and utilization are discussed. Further, a strategy for effective alignment of freeform optics is proposed.
Electronic nose systems have been recently in use for various applications ranging from environme... more Electronic nose systems have been recently in use for various applications ranging from environmental monitoring to biomedical applications. This paper introduces a compact electronic nose system integrating conducting polymer sensors with data acquisition, data processing and storage unit. The data acquisition system presented here is equipped with a graphical user interface (GUI) to control the acquisition parameters as well as perform analysis on obtained data. The real-time data acquisition system is capable of collecting data from an 8X8 resistive sensor array as per the parameters passed by the GUI. Finally, the paper is concluded with results and discussion obtained using the proposed electronic system. The result shows with proper classification algorithm, the system is capable of identifying various amine and alcohol groups.
Optical Design and Fabrication 2019 (Freeform, OFT), 2019
In the present study, a multilayer band pass filter using 11 layers of alternate TiO2 and SiO2 we... more In the present study, a multilayer band pass filter using 11 layers of alternate TiO2 and SiO2 were fabricated on a BK7 substrate using ion assisted electron-beam deposition technique. The filter was designed to have maximum transmission at 545 nm (Green) with adequate bandwidth to allow maximum energy transmission in the green wavelength band. The fabricated filter was found to have a bandwidth of 45 nm with a peak transmission of 91.5% at 545 nm.
Surface errors directly affect the performance of optical systems in terms of contrast and resolu... more Surface errors directly affect the performance of optical systems in terms of contrast and resolution. Surface figure errors at different surface scales are deterministically removed using controlled material removal rate (MRR) during a precision optics fabrication process. We systematically sectioned the wide range of MRR space with systematic parameters and experimentally evaluated and mapped the MRR values using a flexible membrane-polishing tool. We performed numerical analysis with a tool influence function model using a distributed MRR-based Preston’s constant evaluation approach. The analysis procedure was applied to a series of experimental data along with the tool influence function models to evaluate removal rates. In order to provide referenceable survey data without entangled information, we designed the experiments using Taguchi’s L27 orthogonal array involving five control parameters and statistically analyzed a large number of programmatic experiments. The analysis of...
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020
Thermal management of electronic systems is the utmost concern to achieve optimum efficiency unde... more Thermal management of electronic systems is the utmost concern to achieve optimum efficiency under space and weight constraints. For the optimal functioning of a system, the heat generated by the electronic components needs to be dissipated efficiently. The passive cooling technique is extensively used in electronic systems, wherein the more contact surface area of a heat source and the surroundings are utilized. This paper focuses on mathematical and simulation analysis for different types of heat sink designs for the 30 W multi-output DC–DC converter. Heat sink with inverted trapezoidal fins has resulted in efficient thermal management of the converter at its safe operating temperature of 398 K. Results show that the maximum temperature attained by the converter was 352 K which was in the safe operating zone of the converter. A comparative study of the effectiveness of heat dissipation with respect to maximum temperature attained has been discussed. Mathematical verification of Ra...
Ultra-precision machining is used to generate the high quality surfaces in terms of nano-metric s... more Ultra-precision machining is used to generate the high quality surfaces in terms of nano-metric surface finish and sub-micron profile accuracy for various engineering applications. Due to unique properties of diamond i.e. high hardness, good heat conductivity and low friction co-efficient it is most suitable tool material for ultra-precision machining. Advancements in material science and growing needs for modern applications leads to development of new materials. Silicon is one of the prominent materials used for various optical applications. However processing of silicon by machining is quite difficult due to its hard and brittle nature. Diamond tool wear is one of the major issues for ultra-precision machining which leads to increase the process cost significantly. Control of tool wear mainly depends on machining parameter selection and understanding of tool wear mechanism. Wear measurement of diamond tool is essential to understand the wear mechanism, process behavior and tool life quantification. Wear measurement of nano-metric cutting edge is one of the challenging tasks. In current study machining experiments are performed on Silicon. Tool cutting edge is analyzed by profilometric measurements at different orientations. Wear of cutting edge, rake face and flank face is measured. Measurement results are very helpful for understanding the possible reasons of wear and hence to optimize the machining conditions to minimize the tool wear.
Tantalum oxide is a widely used material as a high index layer in multilayer interference filters... more Tantalum oxide is a widely used material as a high index layer in multilayer interference filters for UV, visible and IR filters, laser mirror coatings as well as polarizer and beam splitter applications. In the present study, a single layer of Ta 2 O 5 was deposited on BK7 glass substrate using electron beam evaporation technique in an oxygenated reactive environment. The film was characterized using spectrophotometer and variable angle spectroscopic ellipsometry at angles of 65°, 70° and 75° to extract and estimate its optical constants as well as thickness. The refractive index of the film was found to be 2.0419 at 550 nm for deposition without ion assistance on a heated substrate at 250° C.
2015 Workshop on Recent Advances in Photonics (WRAP), 2015
In this framework, the Refractive elements and the Diffractive element has been combined to explo... more In this framework, the Refractive elements and the Diffractive element has been combined to explore the uniqueness of two domains into one Hybrid system. It was thus targeted to achromatize the optical system and to reduce the overall weight of the system, by incorporating lesser number of optical components to provide similar system performance using Hybrid optical design method. A 60 mm, f/2 Hybrid Petzval projection system with four components covering a 15° field of view has been presented here. The diffractive surface is introduced on the rear surface of the 3rd lens having 71 zones. The minimum zone size is approximately 2.42274 μm and the total chromatic focal shift is limited to 46.12 μm. Optimization and analysis has been performed on Zemax® and the corresponding results are shown.
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Papers by Vinod Karar