Veena Awadhesh Singh
Verified email at kth.se
Postdoctoral Fellow, Department of material Science and Engineering
KTH Royal Institute of Technology, Stockholm, Sweden
EDUCATION
PhD. in Chemistry (2018) Indian Institute of Technology Banaras Hindu University, Varanasi, India
MSc: (2012) Organic Chemistry, University of Pune, Maharashtra, India
BSc: (2010) Chemistry, University of Pune, Maharashtra, India
RESEARCH INTERESTS
Material synthesis, Energy storage, Battery and Supercapacitor, Thin film deposition, Inkjet technology, Magnetic sputtering, Additive manufacturing, Photocatalysis, Solar cells, Renewable energy resources execution, Biofuels, Biodiesel production
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Shilpa Tayal, Anuj Saxena, Veena Singh, Tejinder Kaur, Neetu Singh, Kedar Khare, and Dalip Singh Mehta
Optics and Lasers in Engineering, ISSN: 01438166, Volume: 155, Published: August 2022
Elsevier BV
Shilpa Tayal, Veena Singh, Tejinder Kaur, Neetu Singh, and Dalip Singh Mehta
Journal of Biophotonics, ISSN: 1864063X, eISSN: 18640648, Published: April 2022
Wiley
Multi-modal analysis is highly advantageous for various biomedical applications including cancer and brain studies. Simultaneous measurement of quantitative phase with sub-pixel accuracy and fluorescence image is difficult to achieve in single measurement. Conventionally, off- axis interferograms are analyzed using the Fourier-transform method which limits the accuracy of the phase maps by pixel size, and usually the location of the carrier peak is in sub-pixel. We report a multi-modal microscopic system consisting of high-resolution (HR) quantitative phase interferometer (QPI) to retrieve sub- pixel accuracy in phase imaging and an oblique-illumination based fluorescence imaging system which decouples the excited light from emitted signal light to avoid saturation of the camera, both integrated into a single unit. Here, highly-resolved phase maps are obtained using a two-step process. Firstly, using a speckle-free illumination which offers high spatial phase sensitivity. Secondly, using a hamming window for accurate estimation of original signal frequency information and HR discrete Fourier transform (DFT) which offers sub-pixel accuracy in phase measurements. HR-DFT has computational load of O(ABβ), where A×B is the size of the interferogram and β is the upsampling factor, making system computationally more robust and efficient compared to zero-padded FFT. The experiment is conducted on MG63 osteosarcoma and human mesenchymal stem cells( hMSCs) and their quantitative parameters are extracted with significantly improved accuracy. The average phase for MG63 cells and hMSCs; for nucleus is obtained to be 8.02rad ± 0.80rad and 4.29rad ± 0.43rad ,respectively and for cytoplasm is obtained to be 2.63rad ± 0.96rad and 1.73rad ± 0.57rad, respectively. This article is protected by copyright. All rights reserved.
Priyanka Mann, Veena Singh, Shilpa Tayal, Pramila Thapa, and Dalip Singh Mehta
Journal of Biophotonics, ISSN: 1864063X, eISSN: 18640648, Published: 2022
Wiley
In this paper, we demonstrate the white light phase shifting Interferometer employed as whole slide scanner and phase profiler for determining qualitative and quantitative information over large field-of-view. Experiments were performed on human erythrocytes and MG63 Osteosarcoma cells. Here, we have recorded microscopic images and phase shifted white light interferograms simultaneously in a stepped manner. Sample slide is translated in transverse direction such that there exists a correlation between the adjacent frames, and they were stitched together using correlation functions. Final stitched image has a field-of-view of 0.24*1.14 mm with high resolution ~0.8 μm. Circular Hough transform algorithm is implemented to the resulting image for cell counting and five-step phase shifting algorithm is utilised to retrieve the phase profiles over a large field-of-view. Further, this technique is utilised to study the difference between normal and anaemic erythrocytes. Significant changes are observed in anaemic cells as compared to normal cells. This article is protected by copyright. All rights reserved.
Pramila Thapa, Veena Singh, Sunil Bhatt, Shilpa Tayal, Priyanka Mann, Kiran Maurya, Deepika Mishra, and Dalip Singh Mehta
Journal of Biophotonics, ISSN: 1864063X, eISSN: 18640648, Published: 2022
Wiley
Multimodality of an optical system implies the use of one or more optical techniques to improve the system's overall performance and maximum utility. In this paper, we demonstrate a multi-modal system with oblique illumination that combines two different techniques; fluorescence micro-endoscopy and spectroscopy simultaneously and can be utilized to obtain diverse information from the same location of biological sample. In present system, use of graded-index (GRIN) rod-lens makes it highly compact and oblique incidence decouples illumination geometry with collection geometry, preventing CCD cameras from saturation and reduces number of optical elements, thereby making system further miniaturized and field-portable. It also overcomes disadvantages of undesired reflections from different optical elements. The experimental results of simultaneous imaging and spectroscopy of the biological samples are presented along with quantitative spectroscopic parameters; peak wavelength shift, area under the curve and full width half maximum (FWHM) are calculated. This article is protected by copyright. All rights reserved.
Virendra Kumar, Atul Kumar Dubey, Mayank Gupta, Veena Singh, Ankit Butola, and Dalip Singh Mehta
Optics and Laser Technology, ISSN: 00303992, Volume: 141, Published: September 2021
Elsevier BV
Atul Kumar Dubey, Veena Singh, Mayank Gupta, Virendra Kumar, and Dalip Singh Mehta
Optics and Lasers in Engineering, ISSN: 01438166, Volume: 143, Published: August 2021
Elsevier BV
Shilpa Tayal, Veena Singh, Tejinder Kaur, Neetu Singh, and Dalip Singh Mehta
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, ISSN: 16057422, Volume: 11919, Published: 2021
SPIE
Primala Thapa, Sunil Bhatt, Veena Singh, Shilpa Tayal, Priyanka Mann, Anurag Shrivastava, and Dalip Singh Mehta
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, ISSN: 16057422, Volume: 11919, Published: 2021
SPIE
We describe field-portable GRIN lens based micro-endoscope with oblique-illumination for cancer screening. Fluorescence microscopic images of different samples were recorded with micro-endoscope which provides molecular information about the sample.
Priyanka Mann, Shilpa Tayal, Veena Singh, Pramila Thapa, and Dalip Singh Mehta
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, ISSN: 16057422, Volume: 11919, Published: 2021
SPIE
We report classification between normal and anemic erythrocytes by determining cell counts computationally using Circular Hough transform algorithm in matlab and quantifying phase map which are important for early diagnosis of diseases.
Optics InfoBase Conference Papers, Published: 2021
Optics InfoBase Conference Papers, Published: 2021
Optics InfoBase Conference Papers, Published: 2021
Veena Singh, Shilpa Tayal, and Dalip Singh Mehta
Springer Proceedings in Physics, ISSN: 09308989, eISSN: 18674941, Volume: 258, Pages: 609-612, Published: 2021
Springer Singapore
Pramila Thapa, Hansha Pandey, Veena Singh, Shilpa Tayal, Anurag Shrivastava, and D. S. Mehta
Springer Proceedings in Physics, ISSN: 09308989, eISSN: 18674941, Volume: 258, Pages: 289-292, Published: 2021
Springer Singapore
Priyanka Mann, Veena Singh, Shilpa Tayal, Vishesh Dubey, and Dalip Singh Mehta
Springer Proceedings in Physics, ISSN: 09308989, eISSN: 18674941, Volume: 258, Pages: 625-628, Published: 2021
Springer Singapore
Anuj Saxena, Vishesh Dubey, Veena Singh, Shilpa Tayal, and Dalip Singh Mehta
Springer Proceedings in Physics, ISSN: 09308989, eISSN: 18674941, Volume: 258, Pages: 293-296, Published: 2021
Springer Singapore
Virendra Kumar, Mayank Gupta, Atul Kumar Dubey, Shilpa Tayal, Veena Singh, and Dalip Singh Mehta
Journal of Optics (United Kingdom), ISSN: 20408978, eISSN: 20408986, Published: November 2020
IOP Publishing
Abstract We report the design and development of an efficient speckle reduction device for projection imaging. The device is composed of a combination of a rod-shaped waveguide diffuser and a reflective pyramidal cavity. The simulation results reveal that the pyramidal cavity with waveguide diffuser is a highly efficient light guide comparable to the other conventional light guides. Further, the device was developed and tested experimentally on the basis of speckle contrast and image quality for both the microscopic and macroscopic objects. An acrylic rod-shaped waveguide diffuser was developed and mounted at the middle of a pyramidal shaped cavity which was fabricated using 3D printer. Four highly reflecting mirrors were installed to make the cavity reflective. The system is highly effective for the speckle suppression due to the coherence reduction via multiple scattering from the rod-shaped waveguide diffuser and multiple reflections from the pyramidal cavity. In the system, a combined effect of spatial and angular diversity along with intensity averaging leads to an effective speckle free uniform illumination. Reduced speckle contrast using the proposed system was observed up to 2%, which is nearly equivalent to mechanically moving diffuser system. The device is able to reduce speckle contrast significantly without using any moving parts and in addition, it does not consume any electrical energy. The proposed system is compact, low cost, efficient, and very effective for low to high power laser sources in speckle reduction. Experimental results are compared with stationary and rotating diffuser system on the basis of computed speckle contrast and image quality.
Shilpa Tayal, Veena Singh, Tejinder Kaur, Neetu Singh, and Dalip Singh Mehta
Methods and Applications in Fluorescence, eISSN: 20506120, Published: July 2020
IOP Publishing
Quantitative phase imaging (QPI) technique is used to determine various biophysical parameters, such as refractive index, cell thickness, morphology, etc. On the other hand, fluorescence microscopy is used to acquire information regarding molecular specificity of the biological cells and tissues. Conventionally, a fully coherent light source such as laser is used in QPI technique to obtain the interference fringes with ease; however, its high coherence is also responsible for the generation of speckle and spurious fringes, which results in degraded image quality and affects the phase measurement results too. In this paper, we report a multi-modal system that can be effectively utilized to acquire time varied diverse information about the biological specimen with high spatial phase sensitivity. Herein, a single unit comprising of a fluorescence microscope and the Linnik based interferometer specially equipped with a partially spatially coherent light source illumination was developed. The integrated system is capable to procure molecular specificity and phase information of biological specimen, in a single shot, utilizing a single-chip color CCD camera. Here, we performed experiments on MG63 osteosarcoma cells, and the composite interferometric-fluorescence images were obtained and then digitally decomposed into red and green colors; and, the phase maps were reconstructed using the Fourier fringe analysis method. Furthermore, the cultured cells were monitored over a time-span to observe and investigate the time dependent morphological changes; along with the quantification of cellular adhesion and spreading. Hence, the proposed system can be utilized to quantify time dependent changes in the cell's morphology and in cell adhesion which can be an indicator for the detection of various range of diseases such as arthritis, cancer, osteoporosis and atherosclerosis.
Veena Singh, Vishal Srivastava, and Dalip S. Mehta
Optics and Laser Technology, ISSN: 00303992, Volume: 124, Published: April 2020
Elsevier BV
Virendra Kumar, Kashif Usmani, Veena Singh, Atul Kumar Dubey, Mayank Gupta, and Dalip Singh Mehta
Laser Physics Letters, ISSN: 16122011, eISSN: 1612202X, Published: March 2020
IOP Publishing
Optics InfoBase Conference Papers, Published: 2020
Dalip S. Mehta, Shilpa Tayal, Anuj Saxena, Veena Singh, and Vishesh Dubey
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, ISSN: 16057422, Volume: 11230, Published: 2020
SPIE
We report the development of field-portable multi-modal chip-based fluorescence, bright field and quantitative phase microscopy using smartphone detecting system. Fluorescence microscopy provide molecular information of the specimen with excellent specificity, while phase microscopy provides quantitative information of the specimen. Quantifying the optical phase shifts associated with biological structures gives access to information about morphology and dynamics at the nanometer scale. Here, we propose an integrated waveguide chip-based total internal reflection fluorescence (TIRF) microscopy and quantitative phase microscopy (QPM). We have developed microLED with cylindrical beam profile to couple excitation light into the edges of glass slide easily and efficiently. The evanescent field present on top of a waveguide surface is used to excite the fluorescence and a mobile phone microscope is used to collect the signal. Waveguide chip-based TIRF microscopy benefits from decoupling of illumination and collection light path, large field of view imaging and pre-aligned configuration for multi-color TIRF imaging. Light for bright field imaging and QPM integrated in the transmission mode. A microscope objective is used for collecting the fluorescence excited by evanescent field and transmitted light for bright field and quantitative phase microscopy (QPM). A compact and common path interferometer is used for QPM. The entire device is fabricated using three-D printer and integrated into one, which is compact and field portable. Images are recorded using a smart phone. Experimental results of onion epithelial cells, polystyrene microspheres and normal breast tissue are presented. The cost of entire system is very less.
Dalip S. Mehta, Veena Singh, Shilpa Tayal, Sunil Bhatt, and Vishesh Kumar Dubey
Progress in Biomedical Optics and Imaging - Proceedings of SPIE, ISSN: 16057422, Volume: 11251, Published: 2020
SPIE
Quantitative phase microscopy (QPM) is a label-free imaging technique to quantify various biophysical parameters, such as refractive index, optical thickness, cell dry mass, and dynamic membrane fluctuations. Accurate determination of these parameters requires the use of a QPM system with high temporal phase stability and high spatial phase sensitivity. We report a QPM system based on a common-path interferometer with high temporal phase stability and high spatial phase sensitivity. The proposed QPM system is highly temporally stable, compact and easy to align and implement. The interference pattern can be obtained quickly even with a low coherent light source. In order to realize high spatial phase sensitivity, we used partially spatially coherent (pseudo-thermal) light source for illumination. Due to the partial spatial coherent nature of the light source, a speckle-free interferogram/hologram is recorded over the entire field-of-view. Two types of speckle free QPM systems are implemented using common path Fresnel biprism as well as lateral shearing interferometers. A Fresnel biprism is used in the self-referencing mode, thus offering the advantage of no optical power loss in addition to high temporal stability and the least speckle artifacts. Furthermore, it is very easy to implement, as the system completely replaces the need for spatial filtering at the source end as well as for the reference beam generation. In another configuration, we used a lateral shearing interferometer. The scattered light from the object is collected by the microscope objective lens and passes through a 4mm thick optically flat parallel plate to generate the interference pattern. Phase maps of human RBCs are reconstructed and the results are compared for fully and partially coherent light illumination.
Shilpa Tayal, Veena Singh, Tejinder Kaur, Neetu Singh, and Dalip Singh Mehta
2019 Workshop on Recent Advances in Photonics, WRAP 2019, Published: December 2019
IEEE
In the present work, we have synthesized pseudo- thermal light source and developed the speckle-free quantitative phase interferometric microscope which can be utilized to determine various biological parameters such as morphology, phase, refractive index, cell density etc. We have obtained the phase images of the cultured MG63 cancer cells at different time points for the quantification of different cell stages after seeding. Small changes in the morphology cannot be distinguished using bright field and fluorescence microscopy. But the technique presented in this paper, can quantify morphology and shape of the cell easily.
Veena Singh, Shilpa Tayal, and Dalip Singh Mehta
Optics Communications, ISSN: 00304018, Volume: 451, Pages: 104-110, Published: 15 November 2019
Elsevier BV