Digital holography is a technique that permits digital capture of
holograms and subsequent processing on a digital computer. This
paper reviews various applications of this technique. The presented
applications cover three-dimensional (3-D) imaging as well as several
associated problems. For the case of 3-D imaging, optical and
digital methods to reconstruct and visualize the recorded objects
are described. In addition, techniques to compress and encrypt 3-D
information in the form of digital holograms are presented. Lastly,
3-D pattern recognition applications of digital holography are discussed.
The described techniques constitute a comprehensive approach
to 3-D imaging and processing.

Three-Dimensional Imaging and ProcessingUsing Computational Holographic Imaging

Numerical reconstruction of digital holograms relies on a precise knowledge of the original object position. However, there are a number of relevant applications where this parameter is not known in advance and an efficient autofocusing method is required. This paper addresses the problem of finding optimal focusing methods for use in reconstruction of digital holograms of macroscopic amplitude and phase objects, using digital in-line phase-shifting holography in transmission mode. Fifteen autofocus measures, including spatial-, spectral-, and sparsity-based methods, were evaluated for both synthetic and experimental holograms. The Fresnel transform and the angular spectrum reconstruction methods were compared. Evaluation criteria included unimodality, accuracy, resolution, and computational cost. Autofocusing under angular spectrum propagation tends to perform better with respect to accuracy and unimodality criteria. Phase objects are, generally, more difficult to focus than amplitude objects. The normalized variance, the standard correlation, and the Tenenbaum gradient are the most reliable spatial-based metrics, combining computational efficiency with good accuracy and resolution. A good trade-off between focus performance and computational cost was found for the Fresnelet sparsity method.

Comparative analysis of autofocus functions in digital in-line phase-shifting holography.

Single-pixel imaging is an indirect imaging technique which utilizes simplified optical hardware and advanced computational methods It offers novel solutions for hyper-spectral imaging, polarimetric imaging, three-dimensional imaging, holographic imaging, optical encryption and imaging through scattering media The main limitations for its use come from relatively high measurement and reconstruction times In this paper we propose to reduce the required signal acquisition time by using a novel sampling scheme based on a random selection of Morlet wavelets convolved with white noise While such functions exhibit random properties, they are locally determined by Morlet wavelet parameters The proposed method is equivalent to random sampling of the properly selected part of the feature space, which maps the measured images accurately both in the spatial and spatial frequency domains We compare both numerically and experimentally the image quality obtained with our sampling protocol against widely-used sampling with Walsh-Hadamard or noiselet functions The results show considerable improvement over the former methods, enabling single-pixel imaging at low compression rates on the order of a few percent

/pdf/single-pixel-imaging-with-morlet-wavelet-correlated-random-ovpavresc0.pdf

Single-pixel imaging with Morlet wavelet correlated random patterns

Today people are facing more problems about security in all over world, nowadays security is the most essential issue everywhere in the world; so security of everything gains higher and higher importance in recent years. Here in this paper, trying to reproduce the comprehensive literature study related to the various door locks and gate security systems that are necessary in the fields such as home, industries and vehicle security where possibilities of incursion are increasing day by day. In past days, the research is gone on various door lock security systems like traditional security systems which provide indications using alarm. Due to the advancement in recent techniques, some door lock security systems are based on microcontroller, GSM, GPS, many sensors, software like MATLAB, PROTEUS, biometrics like face recognition, Iris scanner, RFID, Smart Card and password etc. Each system has their own advantages and disadvantages. In most of systems, SMS technique is used for communication so the system will become cost effective, more reliable and it will take less time to deliver message. As security becomes major problem nowadays, the security monitoring systems today needs to

https://www.ijcaonline.org/archives/volume153/number2/nehete-2016-ijca-911971.pdf

Literature Survey on Door Lock Security Systems

Parallel phase-shifting self-interference digital holography with faithful reconstruction using compressive sensing

Compressive Fresnel digital holography using Fresnelet based sparse representation

Compressive complex wave retrieval from a single off-axis digital Fresnel hologram for quantitative phase imaging and microlens characterization

Background/Objectives: Received Signal Strength Indicator (RSSI) is used to determine the position of the Bluetooth device in an indoor environment. Much work had not been reported in tracking the movement of the device using RSSI measurements. It is proposed to design and develop a RSSI logger for a moving Bluetooth device and to analyse the data. Methods/Statistical Analysis: RSSI logger is an embedded system which tracks the distance of a moving Bluetooth user by measuring and logging the RSSI in a time continuous manner. The system is designed by using Raspberry Pi and HC05 Bluetooth devices. Linux Library packages and software are used for development of this Bluetooth tracking. Designed system will plot logged RSSI data on GNUPLOT with respective to other devices. Findings: The graphs are obtained for movement of the device in different scenarios. There is a good coherence observed between the plotted graph and the movement pattern. This will decide behaviour of the systems. RSSI values are useful to track the movement of the person and provide service accordingly, if user comes near an entity he can be serviced, if the user goes away service can be terminated. RSSI computation capability of the Bluetooth devices and Speed of Movement analysis of system observed and calculated. This will be useful in monitoring the movement of some objects within the range of the Bluetooth devices. Conclusion/Improvements: This system can be deployed to monitor and tracking objects moving in a speed of 1m/sec within the range of the Bluetooth devices in a cooperative environment.

Development of an Embedded System to Track the Movement of Bluetooth Devices based on RSSI

The linear relationship between the sample complex object wave and its approximated complex Fresnel field obtained using single shot parallel phase-shifting digital holograms (PPSDH) is used in compressive sensing framework and an accurate phase reconstruction is demonstrated. It is shown that the accuracy of phase reconstruction of this method is better than that of compressive sensing adapted single exposure inline holography (SEOL) method. It is derived that the measurement model of PPSDH method retains both the real and imaginary parts of the Fresnel field but with an approximation noise and the measurement model of SEOL retains only the real part exactly equal to the real part of the complex Fresnel field and its imaginary part is completely not available. Numerical simulation is performed for CS adapted PPSDH and CS adapted SEOL and it is demonstrated that the phase reconstruction is accurate for CS adapted PPSDH and can be used for single shot digital holographic reconstruction.

Phase reconstruction using compressive two-step parallel phase-shifting digital holography

Background/Objectives: Home automation is becoming more important day by day due to its numerous advantages. Home automation technology provides essential security to homes and associated control operations. This paper deals with the design and implementation of secure home automation using Raspberry Pi. Methods/Statistical Analysis: The proposed technology is to design a basic home security application on Raspberry Pi through reading and posting of messages in social networking sites. This data can be shared to authorized user via social networking sites to achieve home automation. Findings: Raspberry Pi board is a flexible embedded processor and with the support of open source packages the required camera system and systems for Facebook management and one time pass word management are implemented. The GPIO pins are sufficient for external control. Conclusion/Improvements: The system developed provides user friendly automation for security of home using Facebook and can be enhanced in future using bio metric authentication.

Prakash Ramachandran

Papers

Compressive Fresnel digital holography using Fresnelet based sparse representation

Compressive complex wave retrieval from a single off-axis digital Fresnel hologram for quantitative phase imaging and microlens characterization

Development of an Embedded System to Track the Movement of Bluetooth Devices based on RSSI

Phase reconstruction using compressive two-step parallel phase-shifting digital holography

Development of Secured Home Automation using Social Networking Sites