Michael Gertsenshteyn

Lobster-eye infrared focusing optics

We propose a new imaging device for the long infrared spectral range, inspired by the natural eye of a lobster. Such a lobster-eye lens is composed of reflecting channels with a square cross section capable of wide angle of view and practically omni-directional imaging. As in large-aperture lenses, aberrations can significantly degrade the image. We show two methods of reducing aberrations: by selecting proper material for the mirrors and by making channels with absorbing sections.

Staring/focusing lobster-eye hard x-ray imaging for non-astronomical objects

A new approach to hard X-ray imaging is proposed, based on staring optics consisting of a lobster-eye lens. This new Staring Imaging Lobster-Eye X-Ray approach is especially suited to X-ray lobster-eye imaging of non-astronomical objects at finite distances, because the staring optics replacing the standard scanning optics, result in an extremely efficient power budget, making possible not only the use of low-efficiency Compton backscattering but also operation with low-flux X-ray beams, increasing operator safety. The lobster-eye optics, consisting of square-cross-section microchannels, transmit an X-ray beam by total external reflection. This mode of operation has already been verified for viewing astronomical objects. Its major challenge is minimizing image defocusing by apodization. For this purpose, a new lens imaging equation is derived, and a new local optical axis concept is defined. Applications include medical imaging, cargo inspection, non-destructive testing, industrial and security safeguards, and surveillance.

Through-the-wall sensor systems based on hard x-ray imaging optics

This paper discusses a new approach to X-ray non-intrusive (NDE) inspection based on hard X-ray imaging optics. A new X-ray lens, called lobster-eye-lens (LEL) is the transmission lens, based on reflection optics, with grazing-angle deflection of 0.2° and photon energy of 40-100 keV. The lens reflection-optics is based on large, high-quality X-ray mirrors with r.m.s. lower than 1 nm. The through-the-wall inspection capability of such a system, based on Compton back-scattering, can be applied for longer ranges, (up to 100 m in the air), and thick walls (over 2 cm for wood, and over 2 mm for metal). CONOPS examples are given for homeland security applications.

Animal eyes in homeland security systems

In this paper, biologically-inspired optical imaging systems, including fish eye, bug eye, lobster eye, and RGB color vision, are discussed as new lensing systems for military and homeland security applications. This new area of interest includes UV, VIS, IR, and X-ray part of electromagnetic spectrum. In particular, recent progress at Physical Optics Corporation will be discussed, including such applications as hyperspectral/multi-spectral imagery, video surveillance, and X-ray inspection.

Finite element Compton tomography

In this paper a new approach to 3D Compton imaging is presented, based on a kind of finite element (FE) analysis. A window for X-ray incoherent scattering (or Compton scattering) attenuation coefficients is identified for breast cancer diagnosis, for hard X-ray photon energy of 100-300 keV. The point-by-point power/energy budget is computed, based on a 2D array of X-ray pencil beams, scanned vertically. The acceptable medical doses are also computed. The proposed finite element tomography (FET) can be an alternative to X-ray mammography, tomography, and tomosynthesis. In experiments, 100 keV (on average) X-ray photons are applied, and a new type of pencil beam collimation, based on a Lobster-Eye Lens (LEL), is proposed.

Hard x-ray devices for target detection at longer distances

Detecting and identifying organic and metallic targets at distances from 50 m to 100 m is difficult for hard X-ray detection devices, especially when targets (such as improvised explosive devices (IEDs)) are concealed behind metal (steel) and non-metal (plastic, wood, rocks, soil, etc.) walls. At least two problems are inherent to detection at such long distances: (1) the air attenuation of X-rays, which can be significant for standoff distances of x = 50 m (100 m total for 2x); and (2) a scattering factor proportional to x4 that comes from the divergence of X-rays propagating from a source to a target and X-rays backscattering from a target (usually, Compton backscattering in low Z-number materials). The compensation of these factors by novel lobster-eye hard X-ray optics is analyzed in this paper. The analysis and the optimization of the hard X-ray lobster eye lens for realistic parameters are also discussed.

Non-scanning x-ray backscattering inspection systems based on x-ray focusing

Non-invasive real-time detection and identification of high explosives and improvised explosive devices, illicit materials hidden inside suitcases, vehicles, containers or behind metal and non-metal walls become critically important for safety and security worldwide. In this paper we will discuss non-scanning, portable real-time detection X-ray backscattering system based on novel Lobster-Eye X-ray focusing optics, which focuses backscatter photons from fully obscured objects several meters away that are being irradiated by short high-power X-ray pulses. Due to the ability of Lobster-Eye lenses to focus X-rays, such imaging systems collect more photons into a smaller spot, compared to traditional pinhole systems. This results in a higher signal-to-noise ratio and better spatial resolution. The signal-to-noise ratio can be further improved by using pulsed X-ray irradiation and a gated X-ray camera. The images can be further improved by software processing, which allows to reconstruct the object with high accuracy adequate for detection with high probability and low false alarm rate.

Inelastic scattering measurements of low energy x-ray photons by organics, soil, water, wood, and metals

The angular distribution of the inelastic scattering of photons at low energies (≤80 KeV) has been measured in organic material, soil, rocks, wood, steel sheet, and water. The measurements have been performed under air inside an X-ray shield cabinet using X-rays tube as a photon source and a thermoelectrically cooled CdTe detector. Measurements have been taken for both single and combined materials. The contributions of inelastic scattering of photons for the lower Z material in a given configuration have been extracted. The measured signal is primarily Compton scattering. The measured inelastic scattering contributions were compared with the calculated inelastic scattering cross sections according to the Klein-Nishina theory, updated to include a practical energy distribution of an X-ray tube beam. Relatively good agreement was found for all targets under investigation. The slight discrepancy is attributed to photoelectric effect and sample configuration. Present results may act as a guide for optimization of X-ray imaging sensors and in particular of those based on lobster eye X-ray optics suitable for cargo inspection, improvised explosives detection, non-destructive evaluation, and medical imaging.