Ariel Schwarz

Superresolved imaging based on wavelength multiplexing of projected unknown speckle patterns

We propose a method for resolution enhancement of a diffraction limited optical system based on the capture of a set of low resolution images. These images are obtained after projection of an ensemble of unknown speckle patterns on top of the high resolution object that is to be imaged. Each speckle pattern is generated by the same thin (and unknown) diffuser, but illuminated with a slightly different wavelength. From the ensemble of low resolution images, we obtain a system of equations that can be solved in an iterative manner that enables reconstruction of the high resolution object. As a result, we also achieve the projected high resolution speckle patterns used for the encoding.

Light intensity and SNR improvement for high-resolution optical imaging via time multiplexed pinhole arrays

In this paper, we present a novel method for pinhole optics with variable pinhole arrays. The imaging system is based on a time multiplexing method using variable and moving pinhole arrays. The improved resolution and signal-to-noise ratio are achieved with improved light intensity in the same exposure time, compared with that of a one-pinhole system. This new configuration preserves the advantages of pinhole optics while solving the resolution limitation problem and the long exposure time of such systems. The system also can be used as an addition to several existing optical systems, which use visible and invisible light and x-ray systems.

Noncontact speckle-based optical sensor for detection of glucose concentration using magneto-optic effect

Abstract. We experimentally verify a speckle-based technique for noncontact measurement of glucose concentration in the bloodstream. The final device is intended to be a single wristwatch-style device containing a laser, a camera, and an alternating current (ac) electromagnet generated by a solenoid. The experiments presented are performed in vitro as proof of the concept. When a glucose substance is inserted into a solenoid generating an ac magnetic field, it exhibits Faraday rotation, which affects the temporal changes of the secondary speckle pattern distributions. The temporal frequency resulting from the ac magnetic field was found to have a lock-in amplification role, which increased the observability of the relatively small magneto-optic effect. Experimental results to support the proposed concept are presented.

Digital Camera Detection and Image Disruption Using Controlled Intentional Electromagnetic Interference

Photography is becoming more and more an end-user capability, with many people having digital cameras on their mobile phones. In general, digital cameras are phasing out traditional film-based equipment. The advantages of digital photography are many: the compactness of the cameras, high reliability, ease of image processing, and transmission of the images via the internet or multimedia messaging. These processes emphasize a big problem which is the ability to photograph an object without the approval of its owner. This unsolved problem has many aspects: the right to privacy, paparazzi, industrial intelligence, and the need to protect objects which have high security sensitivity. This paper describes a method of sensing and then disrupting digital imaging by using a controlled radio frequency transmission. This method can be used in order to create a system that causes a localized malfunction of a digital camera in a specified area so that it will degrade photographic recording done by the digital camera. This method is composed of two stages: coupling the digital camera to a source of intentional electromagnetic interference and generating electromagnetic waves in a specific frequency to interfere with the correct functioning of at least one electronic component of the digital camera.

Remote optical configuration of pigmented lesion detection and diagnosis of bone fractures

In this paper we present a novel approach of realizing a safe, simple, and inexpensive sensor applicable to bone fractures and pigmented lesions detection. The approach is based on temporal tracking of back-reflected secondary speckle pattern generated while illuminating the affected area with a laser and applying periodic pressure to the surface via a controlled vibration. The use of such a concept was already demonstrated for non-contact monitoring of various bio-medical parameters such as heart rate, blood pulse pressure, concentration of alcohol and glucose in the blood stream and intraocular pressure. The presented technique is a safe and effective method of detecting bone fractures in populations at risk. When applied to pigmented lesions, the technique is superior to visual examination in avoiding many false positives and resultant unnecessary biopsies. Applying a series of different vibration frequencies at the examined tissue and analyzing the 2-D speckle pattern trajectory in response to the applied periodic pressure creates a unique signature for each and different pigmented lesion. Analyzing these signatures is the first step toward detection of malignant melanoma. In this paper we present preliminary experiments that show the validity of the developed sensor for both applications: the detection of damaged bones as well as the classification of pigmented lesions.

Optical remote sensor for peanut kernel abortion classification.

In this paper, we propose a simple, inexpensive optical device for remote measurement of various agricultural parameters. The sensor is based on temporal tracking of backreflected secondary speckle patterns generated when illuminating a plant with a laser and while applying periodic acoustic-based pressure stimulation. By analyzing different parameters using a support-vector-machine-based algorithm, peanut kernel abortion can be detected remotely. This paper presents experimental tests which are the first step toward an implementation of a noncontact device for the detection of agricultural parameters such as kernel abortion.

Digital camera sensing and its image disruption with controlled radio-frequency reception/transmission

Photography is becoming more and more end user capability, with many people having digital cameras on their mobile phones. In general digital cameras are phasing out traditional film based equipment. The advantages of digital photography include the compactness of the cameras, high reliability and ease of image processing and transmission of the images via the internet or multimedia messaging (MMS) enabling the photographer to send his images within seconds. These processes emphasize a big problem: the ability to photograph an object without the approval of its owner. This unsolved problem has many aspects: the right to privacy, paparazzi, industrial intelligence and the protection of objects having high security sensitivity. This paper describes test methodology and test results to sense and then to disrupt digital imaging camera by using a controlled Radio Frequency (RF) transmission. This method can be used in order to create a system for causing a localized malfunctioning of a digital camera in a specified area to degrade photographic recording done by the digital camera, comprising the steps of coupling the digital camera to a source of electromagnetic interference and generating electromagnetic waves in a specific frequency to interfere with the correct functioning of at least one electronic component of the digital camera.

Demonstration of a Speckle Based Sensing with Pulse-Doppler Radar for Vibration Detection

In previous works, an optical technique for extraction and separation of remote static vibrations has been demonstrated. In this paper, we will describe an approach in which RF speckle movement is used to extract remote vibrations of a static target. The use of conventional radar Doppler methods is not suitable for detecting vibrations of static targets. In addition, the speckle method has an important advantage, in that it is able to detect vibrations at far greater distances than what is normally detected in classical optical methods. The experiment described in this paper was done using a motorized vehicle, which engine was turned on and off. The results showed that the system was able to distinguish between the different engine states, and in addition, was able to determine the vibration frequency of the engine. The first step towards real time detection of human vital signs using RF speckle patterns is presented.

Sensitivity enhanced photo-thermal borders detection in bio-phantoms enriched with gold nanoparticles

In the last decade diversity of applications in the fields of diagnostics and treatment for biomedical applications using gold nanoparticles (GNPs) as contrast agent sprang up. The strong optical absorption and scattering properties of the GNPs due to their localized surface plasmon resonance (LSPR) effect enables their use as contrast agents in these applications. The usage of the light-scattering properties of the GNPs in most imaging methods lead to background noise stems from light scattering from the tissue due to the same wavelengths of the illumination source and the GNPs’ scattering. In our previous works we presented a method to improve border detection of bio-phantoms enriched with GNPs leading for real-time complete tumor resection by using a modulated laser illumination, photo thermal imaging camera and the optical absorption of specially targeted GNPs. In this system the thermal camera detects the temperature field of the illuminated bio-phantoms. Although the surrounding area got heated the border location was detected at a precision of at least 0.5 mm through use of a simple post processing technique. In this paper, we present a continuation of our previous research with modified system of time sequence labelling (TSL) processing for improved border detection capable of operating and detecting borders at much lower signal to noise levels. Copyright

Computational expansion of imaging from visible to IR and gamma imaging systems

Lenses are used for imaging in a wide range of applications, but in many cases this leads to drawbacks. For example, in smart phone cameras the use of imaging lenses limits the flatness of the device, and in medical devices, such as micro-endoscopes, the field of view (FOV) is limited. In many applications, such as terahertz (THz) imaging—used for security purposes—or gammaray imaging, which is used in single-photon emission computed tomography (SPECT), conventional imaging lenses cannot be used. Instead, existing THz detectors require space scanning and bulky hemispherical lenses or mirrors,1 whereas gamma-ray imaging requires an array of collimators to allow only forwardpropagating rays to pass. We have found that the integration of a time-variable array of pinholes can be used to carry out high-resolution imaging. This array provides high energy efficiency if it is used to replace an imaging lens,2 and it can significantly extend the FOV3 if it is integrated into the aperture plane of an imaging lens. Avoiding the use of imaging lenses enables much flatter and cheaper imaging optics to be used in the visible and near-IR regions, and also in other spectral regions in which the use of conventional lenses is not feasible. Whether the array is used to replace a lens, or is integrated into a lens, its operating principle involves time-variable encoding of the aperture plane, followed by decoding to recover the resolution and FOV of the enhanced image. We have demonstrated experimental results for both the above-mentioned uses of the array.4 We achieved lens-free imaging by combining a variableaperture wheel, as shown in Figure 1, with a CCD sensor. Figure 1. Left: Variable-aperture wheel for use in combination with a CCD sensor to acquire images. Right: Experimental setup using the screen of a smartphone to display the imaged object.