Instruments Research and Development Establishment

Dehradun, India

Instruments Research and Development Establishment

Dehradun, India
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Mishra S.K.,Instruments Research and Development Establishment | Ghosh A.,Instruments Research and Development Establishment | Gupta A.K.,Defense Electronics Application Laboratory
Optics InfoBase Conference Papers | Year: 2016

This paper reports atmospheric turbulence effects on a Gaussian laser beam from an airborne platform to a submerged vessels in deep sea. Beam wander, beam spreading and scintillations effects have been considered for bit-error-rate (BER) analysis. © OSA 2016.

Bhatt M.,Instruments Research and Development Establishment | Nautiyal B.B.,Instruments Research and Development Establishment | Bandyopadhyay P.K.,Instruments Research and Development Establishment
Infrared Physics and Technology | Year: 2010

Antireflection coatings have critical importance in thermal imaging system working in MWIR region (3-5 μm) since optics of high refractive index materials are used. Germanium (Ge) and Silicon (Si) optics are used extensively in the MWIR thermal systems. In this paper a study has been carried out on the design and fabrication of multi-substrate antireflection coating effective for Germanium and Silicon optics in MWIR (3.6-4.9 μm) region. The wave band 3.6-4.9 μm is chosen for the reported work because detector system used in MWIR region has a band selection filter effective in the same wavelength region and atmospheric transmission window in MWIR region is effective in 3-5 μm spectral band. Comprehensive search method was used to design the multilayer stack on the substrate. The coating materials used in the design were Germanium (Ge), Hafnium oxide (HfO 2) and Y-Ba-Fluoride (IR-F625). The fabrication of coating was made in a coating plant fitted with Cryo pump system and residual gas analyzer (RGA). The evaporation was carried out at high vacuum (2-6 × 10 -6 mbar) with the help of electron beam gun system and layer thicknesses were measured with crystal monitor. The result achieved for the antireflection coating was 98.5% average transmission in 3.6-4.9 μm band for Germanium and Silicon optics. This work will be helpful in reducing the plant operation time, material and power consumption, as two different kinds of optics are simultaneously coated in a single coating cycle. © 2009 Elsevier B.V. All rights reserved.

Pawar M.,Instruments Research and Development Establishment
2012 IEEE International Conference on Computational Intelligence and Computing Research, ICCIC 2012 | Year: 2012

Mean shift based face tracking is able to track face nicely under controlled conditions. It usually fails when there is noise and rapid illumination variations over face. The main reason for failure is that mean shift employs fixed histogram based target model representation. In this paper we present a novel technique of continuously updating the target model histogram for more robust mean shift based face tracking using a Bayesian skin classifier. We used Bayesian skin classifier to learn new skin color features from face templates in successive frames. The classifier use likelihood ratio for extracting new skin color features from each new face template. The Bayesian skin classifier had been used mainly for detection of skin parts in images but we extend this idea to continuously update the target model histogram with learned features to accommodate the dynamics of pose change and illumination in a video sequence for more robust face tracking. © 2012 IEEE.

Negi R.,Instruments Research and Development Establishment
Proceedings 12th International Conference on Fiber Optics and Photonics, Photonics 2014 | Year: 2014

This paper presents a novel technique to design complex periodic pattern for the 2D photonic crystal using Talbot self-imaging.The plane wave simulation in RSoft software exhibits photonic bandgaps for these 2D periodic structures. © OSA 2014.

Kumar A.,Instruments Research and Development Establishment
Defence Science Journal | Year: 2013

The advancement in infrared (IR) detector technologies from 1st to 3rd generation and beyond has resulted in the improvement of infrared imaging systems due to availability of IR detectors with large number of pixels, smaller pitch, higher sensitivity and large F-number. However, it also results in several problems and most serious of them is sensor non-uniformities, which are mainly attributed to the difference in the photo-response of each detector in the infrared focal plane array. These spatial and temporal non-uniformities result in a slowly varying pattern on the image usually called as fixed pattern noise and results in the degradation the temperature resolving capabilities of thermal imaging system considerably. This paper describes two types of non uniformity correction methodologies. First type of algorithms deals with correction of sensor non-uniformities based upon the calibration method. Second type of algorithm deals with correction of sensor non uniformities using scene information present in the acquired images. The proposed algorithms correct both additive and multiplicative non uniformities. These algorithms are evaluated using the simulated & actual infrared data and results of implementations are presented. Furthermore, proposed algorithms are implemented in field programmable gate array based embedded hardware. © 2013, DESIDOC.

Gupta V.,Instruments Research and Development Establishment | Sunita,Instruments Research and Development Establishment
Advances in Intelligent Systems and Computing | Year: 2016

To recognize the Hindi characters using perceptron learning rule an algorithm is modeled and simulated in this paper. This model maps a matrix of pixels into characters on scanned images. In this paper perceptron learning rule is modeled based on mapping of input and output matrix of pixels. Perceptron learning rule uses an iterative weight adjustment that is more powerful than other learning rules. The perceptron uses threshold output function and the McCulloch– Pitts model of a neuron. Their iterative learning converges to correct weight vector, i.e., the weight vector that produces the exact output value for the training input pattern. For modeling and simulation, those Hindi characters are used which are similar to some of numeric numbers. To model and simulate the algorithm, Hindi characters are taken in form of the 5 × 3 matrix of pixels. © Springer Science+Business Media Singapore 2016.

Naraniya O.P.,Instruments Research and Development Establishment | Naraniya O.P.,Indian Institute of Technology Delhi | Shenoy M.R.,Indian Institute of Technology Delhi | Thyagarajan K.,Indian Institute of Technology Delhi
Applied Optics | Year: 2012

We present numerical results for optimization of the overall idler conversion efficiency of a nanosecond optical parametric oscillator (OPO), wherein the signal generated in the OPO process is also used as the pump for a difference frequency generation (DFG) process in a quasi-periodic MgO:LiNbO 3 crystal. The phase-matching conditions are considered such that the generated idler frequencies in both the processes (i.e., OPO and DFG) coincide. Optimization for the idler generation has been performed with respect to the different parameters, such as input pump power, pump pulse duration, and the output coupler reflectivity, for quasi-phase-matched interaction in MgO:LiNbO3. Wavelength of the pump, signal, and idler waves considered in the optimization are 1.064 μm, 1.456 μm, and 3.95 μm, respectively. A maximum overall idler generation efficiency of 33% could be obtained in the simultaneous OPO + DFG process for a pump pulse duration of 72 ns and output coupler reflectivity (Rs) of 90%, whereas for the stand-alone OPO process, the maximum idler generation efficiency was found to be 15%. The optimization has been illustrated for an average pump power of 8 Wat a pulse repetition frequency (PRF) of 10 kHz. This approach of simultaneous OPO + DFG process can be employed to significantly enhance the idler generation efficiency of nanosecond OPOs. © 2012 Optical Society of America.

Mishra S.K.,Instruments Research and Development Establishment | Gupta A.K.,Instruments Research and Development Establishment | Sharma A.,Indian Institute of Technology Delhi
Journal of Modern Optics | Year: 2012

A modal wavefront sensor for ocular aberrations exhibits two main advantages compared to a conventional Shack-Hartmann sensor. As the wavefront is detected in the Fourier plane, the method is robust against local loss of information (e.g. local opacity of ocular lens as in the case of cataract), and is not dependent on the spatial distribution of wavefront sampling. We have proposed a novel method of wavefront sensing for ocular aberrations that directly detects the strengths of Zernike aberrations. A multiplexed Fourier computer-generated hologram has been designed as the binary phase element (BPE) for the detection of second-order and higher-order ocular aberrations (HOAs). The BPE design has been validated by comparing the simulated far-field pattern with the experimental results obtained by displaying it on a spatial light modulator. Simulation results have demonstrated the simultaneous wavefront detection with an accuracy better that /30 for a measurement range of 2.1 with reduced cross-talk. Sensor performance is validated by performing a numerical experiment using the City data set for test waves containing second-order and HOAs and measurement errors of 0.065m peak-to-valley (PV) and 0.08m (PV) have been obtained, respectively. © 2012 Copyright Taylor and Francis Group, LLC.

Pandey N.,Indian Institute of Technology Delhi | Ghosh A.,Instruments Research and Development Establishment | Khare K.,Indian Institute of Technology Delhi
Applied Optics | Year: 2016

We report a method for two-dimensional phase unwrapping based on the transport of intensity equation (TIE). Given a wrapped phase profile, we generate an auxiliary complex field and propagate it to small distances to simulate two intensity images on closely spaced planes. Using the longitudinal intensity derivative of the auxiliary field as an input, the TIE is solved by employing the regularized Fourier-transform-based approach. The resultant phase profile is automatically in the unwrapped form, as it has been obtained as a solution of a partial differential equation rather than as an argument of a complex-valued function. Our simulations and experimental results suggest that this approach is fast and accurate and provides a simple and practical solution for routine phase unwrapping tasks in interferometry and digital holography. © 2016 Optical Society of America.

Upadhyaya A.S.,Instruments Research and Development Establishment | Bandyopadhyay P.K.,Instruments Research and Development Establishment
Journal of Physics: Conference Series | Year: 2012

In state of art technology, integrated devices are widely used or their potential advantages. Common system reduces weight as well as total space covered by its various parts. In the state of art surveillance system integrated SWIR and night vision system used for more accurate identification of object. In this system a common optical window is used, which passes the radiation of both the regions, further both the spectral regions are separated in two channels. ZnS is a good choice for a common window, as it transmit both the region of interest, night vision (650 - 850 nm) as well as SWIR (0.9 - 1.7 μm). In this work a broad band anti reflection coating is developed on ZnS window to enhance the transmission. This seven layer coating is designed using flip flop design method. After getting the final design, some minor refinement is done, using simplex method. SiO2 and TiO2 coating material combination is used for this work. The coating is fabricated by physical vapour deposition process and the materials were evaporated by electron beam gun. Average transmission of both side coated substrate from 660 to 1700 nm is 95%. This coating also acts as contrast enhancement filter for night vision devices, as it reflect the region of 590 - 660 nm. Several trials have been conducted to check the coating repeatability, and it is observed that transmission variation in different trials is not very much and it is under the tolerance limit. The coating also passes environmental test for stability.

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