Browsing by Author "Kumar, Manoj"

Now showing 1 - 4 of 4

Interferenceless incoherent digital holography with binary coded apertures optimized using direct binary search
(Elsevier B.V., 2022) Kumar, Manoj; Anand, Vijayakumar; Rosen, Joseph
Coded aperture correlation holography offers 3D imaging with improved lateral and axial resolutions. This study is an additional advancement in the line of imaging systems with a pseudorandom coded aperture. Starting with the coded aperture correlation holography system implemented on an incoherent on-axis interferometer, we proposed interferenceless and lensless versions of the system. In the present study, we propose replacing the multi-values phase aperture mask with a binary mask. Two binary masks synthesized iteratively are used in two camera shots. Each mask is obtained from an iterative optimization process known as direct binary search, where the optimized cost function is the peak-to-background ratio of a reconstructed point object. Overall, the system demonstrates a lower background noise compared to other methods, enabling 3D imaging capability with only two camera shots, a substantial improvement in comparison to the many shots in the original systems. Using binary masks might extend the usefulness of the coded aperture holography for new regions in the electromagnetic spectrum other than the visual band, as of X-ray and THz bands.
Interferenceless incoherent digital holography with binary coded apertures optimized using direct binary search
(2023) Kumar, Manoj; Anand, Vijayakumar; Rosen, Joseph
Coded aperture correlation holography offers 3D imaging with improved lateral and axial resolutions. This study is an additional advancement in the line of imaging systems with a pseudorandom coded aperture. Starting with the coded aperture correlation holography system implemented on an incoherent on-axis interferometer, we proposed interferenceless and lensless versions of the system. In the present study, we propose replacing the multi-values phase aperture mask with a binary mask. Two binary masks synthesized iteratively are used in two camera shots. Each mask is obtained from an iterative optimization process known as direct binary search, where the optimized cost function is the peak-to-background ratio of a reconstructed point object. Overall, the system demonstrates a lower background noise compared to other methods, enabling 3D imaging capability with only two camera shots, a substantial improvement in comparison to the many shots in the original systems. Using binary masks might extend the usefulness of the coded aperture holography for new regions in the electromagnetic spectrum other than the visual band, as of X-ray and THz bands.
Nonlinear Reconstruction of Images from Patterns Generated by Deterministic or Random Optical Masks—Concepts and Review of Research
(Journal of Imaging, 2022) Smith, Daniel; Gopinath, Shivasubramanian; Arockiaraj, Francis Gracy; Reddy, Andra Naresh Kumar; Balasubramani, Vinoth; Kumar, Ravi; Dubey, Nitin; Ng, Soon Hock; Katkus, Tomas; Selva, Shakina Jothi; Renganathan, Dhanalakshmi; Kamalam, Manueldoss Beaula Ruby; Rajeswary, Aravind Simon John Francis; Navaneethakrishnan, Srinivasan; Inbanathan, Stephen Rajkumar; Valdma, Sandhra-Mirella; Praveen, Periyasamy Angamuthu; Amudhavel, Jayavel; Kumar, Manoj; Ganeev, Rashid A.; Magistretti, Pierre J.; Depeursinge, Christian; Juodkazis, Saulius; Rosen, Joseph; Anand, Vijayakumar
Indirect-imaging methods involve at least two steps, namely optical recording and computational reconstruction. The optical-recording process uses an optical modulator that transforms the light from the object into a typical intensity distribution. This distribution is numerically processed to reconstruct the object’s image corresponding to different spatial and spectral dimensions. There have been numerous optical-modulation functions and reconstruction methods developed in the past few years for different applications. In most cases, a compatible pair of the optical-modulation function and reconstruction method gives optimal performance. A new reconstruction method, termed nonlinear reconstruction (NLR), was developed in 2017 to reconstruct the object image in the case of optical-scattering modulators. Over the years, it has been revealed that the NLR can reconstruct an object’s image modulated by an axicons, bifocal lenses and even exotic spiral diffractive elements, which generate deterministic optical fields. Apparently, NLR seems to be a universal reconstruction method for indirect imaging. In this review, the performance of NLR is investigated for many deterministic and stochastic optical fields. Simulation and experimental results for different cases are presented and discussed
Serveriprii arvutus värkvõrgu jaoks
(2018) Kumar, Manoj; Mario Di Francesco and Satish Narayana Srirama
Pilvepõhised teenused on aastate jooksul teinud märkimisväärse arengu. Pilvearvutuse mudelid nagu IaaS, PaaS ja SaaS pakuvad alternatiive traditsioonilistele erataristu-põhistele lähenemistele. Serveriprii arvutus on pilvearvutuse mudel efemeersete, olekuta ja sündmusepõhiste rakenduste jaoks, mis kiirelt skaleeruvad. Vastupidiselt pilvearvutusele, kus ressursse jagub pea lõpmatult, koosneb värkvõrk arvutuslikult piiratud ressurssidega heterogeensetest ja intelligentsetest seadmetest, mis toodavad märkimisväärsetes kogustes andmeid. Värkvõrgu ressursipiiratuse tõttu kasutatakse selliste andmete töötluseks pilveresursse, kuid pilve kasutamine toob kaasa ka mõned piirangud - suurenenud latentsus ning privaatsusprobleemid. Seetõttu tekib vajadus kohalikuks andmetöötluseks värkvõrgu seadmetel. Moodustades tarkvarakonteinerite abil värkvõrgu seadmetel klastri, on võimalik luua serveriprii platvorm kohalikuks andmetöötluseks. Käesolev töö esitleb hübriidset, mitmekihilist arhitektuuri, mis lisaks kohalikule sensorandmete töötlusele arvestab ka probleeme nagu seadmete heterogeensus ja ressursipiiratus. Loodud lahenduses kasutame tarkvarakonteinereid ning mitmekihilist arhitektuuri, et tagada kõrge käideldavus ja rikketaluvus.