Abstract: We examine the Seidel aberrations of thin spherical lenses composed of media with refractive index not restricted to be positive. We find that consideration of this expanded parameter space allows for the reduction or elimination of more aberrations than is possible with only positive index media. In particular, we find that spherical lenses possessing real aplanatic focal points are possible only with a negative index. We perform ray tracing, using a custom code that relies only on Maxwell's equations and conservation of energy, that confirms the results of the aberration calculations.

Abstract: An X-ray CT apparatus capable of imaging a subject based on X-rays of multiple energy levels while using an ordinary X-ray detector includes an X-ray tube which generates X-rays from multiple focal points of different 3-dimensional positions sequentially on a time-division basis, a plurality of filters which implement the filtering individually for the X-rays generated individually from the focal points, a collimator which equalizes the irradiation range of the X-rays generated individually from the focal points, collection means which collects projection data of multiple views of a subject of imaging for the X-rays generated individually from the focal points, and reconstruction means which reconstructs an image based on the projection data. The anode of the X-ray tube has multiple impingement portions where electrons released by the cathode impinge at multiple positions on the trajectory of electrons sequentially on a time-division basis.

Abstract: Vibro-acoustography is a method that produces images of the acoustic response of a material to a localized harmonic motion generated by ultrasound radiation force. The low-frequency, oscillatory radiation force (e.g., 10 kHz) is produced by amplitude modulating a single ultrasound beam, or by interfering two beams of slightly different frequencies. Proper beam forming for the stress field of the probing ultrasound is very important because it determines the resolution of the imaging system. Three beam-forming geometries are studied: amplitude modulation, confocal, and x-focal. The amplitude of radiation force on a unit point target is calculated from the ultrasound energy density averaged over a short period of time. The profiles of radiation stress amplitude oil the focal plane and on the beam axis are derived. The theory is validated by experiments using a small sphere as a point target. A laser vibrometer is used to measure the velocity of the sphere, which is proportional to the radiation stress exerted on the target as the transducer is scanned over the focal plane or along the beam axis. The measured velocity profiles match the theory. The theory and experimental technique may be useful in future transducer design for vibro-acoustography.

Abstract: A system for optical imaging of a thick specimen (1) that permits rapid acquisition of data necessary for tomographic reconstruction of the three-dimensional (3D) image. One method involves the scanning of the focal plane of an imaging system (60, 61) and integrating the range of focal planes onto a detector (43). The focal plane of an optical imaging system (60, 61) is scanned along the axis perpendicular to said plane through the thickness of a specimen (1) during a single detector exposure. Secondly, methods for reducing light scatter when using illumination point sources (11) are presented. Both approaches yield shadowgrams. This process is repeated from multiple perspectives, either in series using a single illumination/detection subsystem, or in parallel using several illumination/detection subsystems. A set of pseudo-projections is generated, which are input to a three dimensional tomographic image reconstruction algorithm (74).

Abstract: An improved system and method for obtaining images of a microscope slide are provided. In one embodiment, a focus camera (22) includes an optical sensor that is tilted relative to the focal plane of a scanning camera (32). A scan of a target region (14) are captured from a plurality of X-Y position. Each image contains information associated with multiple focal planes.

Abstract: Systems and methods for microbolometer focal plane arrays are disclosed. For example, in accordance with an embodiment of the present invention, microbolometer focal plane array circuitry is disclosed for a microbolometer array having shared contacts between adjacent microbolometers. Various techniques may be applied to compensate for non-uniformities, such as for example, to allow operation over a calibrated temperature range.

Abstract: We report the use of starch as an ideal nonlinear medium with which to perform collinear frequency-resolved optical gating measurements of ultrashort pulses at the focal plane of a high-numerical-aperture (NA) lens. We achieved these measurements by simply sandwiching starch granules (suspended in water) between two coverslips and placing them within the focal plane of a high-NA lens. The natural nonlinear characteristics of starch allow the correct phase matching of pulses at the focal plane of a high-NA lens at different wavelengths. This elegant arrangement overcomes all the complexity and problems that were previously associated with pulse characterization within a multiphoton microscope.

Abstract: Elliptical reflectors are widely used in illumination engineering as a means to concentrate the light of a source in the secondary focal plane. To collect as much light from the source as possible, the reflector must cover a wide angular range of the emitted radiation, hence forward and backward reflections on the reflector must be discussed and conditions for paraxial optics do not apply. We develop a framework of relations that describe the image of an extended source in the secondary focal plane of the ellipsoid. After deriving basic relations between object and image spaces, the propagation of rays depending of their origin and on their direction is investigated. As a result, the function and the aberrations of the reflector can be expressed in terms of an angular dependent magnification for longitudinal and lateral coordinates. With that, one cannot not only calculate luminance and illuminance distributions in the secondary focal plane in a straightforward manner, but can easily understand their properties and their dependence on ellipse parameters. On the basis of the developed relations, implications for the design of "elliptical" short arc high-intensity-discharge (HID) lamps for video projection are discussed.

Abstract: A high-frequency imaging system for the millimeter and submillimeter radiation includes a high frequency lens to image an object at its focal plane. The object emits electromagnetic radiation at a first frequency above the microwave band of the electromagnetic spectrum. A local oscillator generates an electromagnetic beam at a second frequency to illuminate a plurality of dual-frequency antennas at the focal plane of the lens. Intermodulation of first and second frequencies generates a signal distribution of a third frequency over the focal plane, which represents an image. Also, a method of providing an image at the third frequency of an object emitting electromagnetic radiation at a first frequency is provided. The method includes imaging the electromagnetic radiation at the first frequency from each point of the object onto the focal plane. An electromagnetic beam is transmitted to illuminate all elements of the focal plane array.

Abstract: We design a new frequency-domain, finite-difference approach, based on a displacement formulation, which correctly describes the stress-free conditions at a free surface. In the conventional, displacement-based finite-difference method, we assign both displacements and material properties such as density and Lame constants to nodal points (a node-based grid set), whereas in our new finite-difference method, displacements are still defined at nodal points but material properties within cells (a cell-based grid set). In our new finite-difference technique using the cell-based grid set, stress-free conditions at the free surface are described by the changes in the material properties without any additional stress-free boundary condition. By conducting accuracy tests, we confirmed that the new second-order finite differences formulated in the cell-based grid set generate numerical solutions compatible with analytic solutions within the range of errors determined by dispersion analysis; the new, cell-based, weighted-averaging finite-difference method also yields better solutions than the old, node-based, weighted-averaging finite-difference method. The cell-based finite-difference method does not violate the reciprocity.

Abstract: A scalable laser scanning angle apparatus and method of scaling a scanning angle using MEMS devices and elliptical mirrors includes disposing a first scanner at one focal point of an elliptical mirror and scanning the emitted light beam in a first direction at a first scanning angle toward a concave surface of the elliptical mirror such that the scanned light beam is directed toward the second focal point of the elliptical mirror, and scanning the light beam from the concave surface of the elliptical mirror in a second direction at a second scanning angle using a second scanner, wherein the second scanner outputs the light beam across a system scanning angle which corresponds to a combination of the first scanning angle and the second scanning angle. The scanning angle is scalable by repeatedly scanning the light beam at corresponding focal points of a predetermined number of elliptical mirrors, wherein the total scanning angle is scaled by a multiple of a number of times the light beam is scanned.

Abstract: We present a holographic lens with novel features recorded in an azopolymer film. Two holographic modulations, bulk birefringence and surface relief, are induced in the medium at the same time. The resultant holographic element has two focal planes, and the polarization of light in the focal points depends on the polarization of the incident light. Applications of this device for writing-reading information in two planes simultaneously or separately are described.

Abstract: Method and apparatus for heating plastic by laser beams with the aid of a number of laser points on the focal plane, the laser points being produced by an optical arrangement with the aid of a multiple wedge plate. The arrangement can be integrated in a processing head.

Abstract: Light that is scattered from lenses and mirrors in an optical system produces a halo of stray light around bright objects within the field of view. The angular distribution of scattered light from any one component is usually described by the Harvey model. This paper presents analytic expressions for the scattered irradiance at a focal plane from optical components that scatter light in accordance with the Harvey model. It is found that the irradiance is independent of the location of an optical element within the system, provided the element is not located at or near an intermediate image plane. It is also found that the irradiance has little or no dependence on the size of the element.

Abstract: A wavefront measurement system (106) includes a source of electromagnetic radiation (103). An imaging system (M3, M4) directs the electromagnetic radiation at an object plane that it uniformly illuminates. A first grating (201) is positioned in the object plane to condition the radiation entering the input of a projection optic. A projection optical system (104) projects an image of the first grating onto the focal plane. A second grating (203) is positioned at the focal plane that receives a diffracted image of the source to form a shearing interferometer. A CCD detector (202) receives the image of the first grating (201) through the projection optical system (104) and the second grating (203) that forms a fringe pattern (312) if there are aberrations in the projection optical system. Phaseshift readout of fringe pattern can be accomplished by stepping the first grating (201) in a lateral direction and reading each frame with the CCD detector. The first grating (201) includes a plurality of reflecting lines (1202) each formed by a plurality of reflecting dots (1204). The first grating has a pitch that is ½ times the magnification of the projection system times the pitch of the second grating for achromatic operation.

Abstract: Temporal, thermal and spatial performances of some FPA cameras have been tested. Different disturbing behaviors related to this recent technology have been pointed out, especially with a view to research and development applications.

Abstract: A system for enhancing images from an electro-optic imaging sensor and for reducing the necessary focal length of a sensor while preserving system acuity. This system uniquely reduces the necessary focal length and enhances images by collecting a video sequence, estimating motion associate with this sequence, assembling video frames into composite images, and applying image restoration to restore the composite image from pixel, lens blur, and alias distortion. The invention synthetically increases the pixel density of the focal plane array. Thus it reduces the necessary size of the projected blur circle or equivalently it reduces the minimum focal length requirements.

Abstract: A method of generating an image sequence that includes the steps of detecting scene irradiance using detectors in a focal plane array, generating an output image sequence for each of the detectors based on the detected irradiance, and correcting the output image sequence generated by a first subset of detectors in the focal plane array and the output image sequence generated by a second subset of detectors in the focal plane array using the correction provided to the first subset of detectors.

Abstract: A new method for designing holographic optical elements is presented. The method is based on matching the grating-spacing profile of the recording light interference pattern to the desired grating-spacing profile. We show that for designing near-field holograms, in which the optical images involved are close to the hologram aperture, the grating-matching technique is superior to the well-established aberration-balancing method introduced by Latta [Appl. Opt.10, 609 (1971)].

Abstract: A thermal imaging apparatus comprises a thermal image camera having a lens and a display. The camera further includes a focal plane array located behind the lens for converting imaging radiation to produce an image signal for further processing. A shutter mechanism is operative to selectively inhibit exposure of the focal plane array to the imaging radiation such that the focal plane array produces a reference signal. Processing circuitry is operative to receive the image signal and produce a corresponding thermal image on the display. The processing circuitry is further operative to utilize the image signal and the reference signal to derive temperature information.

Abstract: An imaging optical system (22) has an optical axis (34) and a refractive optical group (38) including a lens (40, 42, or 44) lying on the optical axis (34). At least one lens (40, 42, and/or 44) of the refractive optical group (38) lying on the optical axis (34) has an aspheric front surface and an aspheric back surface. An image surface (28) lies on the optical axis (34), and the refractive optical group (38) forms -an image at the image surface (28). The image surface (28) is preferably substantially planar. A detector (30), such as a focal plane array detector (30), lies on the optical axis (34) such that a ray of light passing through the lens (40, 42, and 44) is incident upon the detector (30). It is preferred that there are two lenses lying on the optical axis (34), with each lens having an aspheric front surface and an aspheric back surface. The imaging optical system (22) is suitable for use as a large-aperture, widefield-of-view, compact system having an F number of less than about F/ 1. 5, a field of view of more than about 45 degrees, and a telephoto ratio of less than about 2.0.

Abstract: We describe the design and expected performance of Clover, a new instrument designed to measure the B-mode polarization of the cosmic microwave background. The proposed instrument will comprise three independent telescopes operating at 90, 150 and 220 GHz and is planned to be sited at Dome C, Antarctica. Each telescope will feed a focal plane array of 128 background-limited detectors and will measure polarized signals over angular multipoles 20 < l < 1000. The unique design of the telescope and careful control of systematics should enable the B-mode signature of gravitational waves to be measured to a lensing-confusion-limited tensor-to-scalar ratio r~0.005.

Abstract: Optical remote sensing images are usually acquired according to the classical pushbroom principle. A linear array of CCD detectors, placed in the focal plane of the telescope, acquires a scanline over an integration time. The satellite's motion along its orbit, which is perpendicular to the linear array, ensures acquisition of successive lines. Because of inter-detector sensitivity differences, the image of a uniform landscape is striped vertically. Detector normalization aims at correcting these relative sensitivities and delivering uniform images of uniform areas. Determination of inter-detector coefficients requires observation of one uniform landscape, provided that each detector behaves linearly. High resolution optical satellites like the future French PLEIADES-HR have to face a lack of signal, which moves the useful signal range towards the non-linear part of the detector response. For such designs, normalization has to be run with a non-linear model : this is a cost-effective way to improve image quality at low radiances and relax detector sorting. Regarding in-flight operations, non-linear parameters identification requires observation of several uniform landscapes and may be actually very difficult to run, because of the uniformity constraint. An efficient way to bypass the quest of uniformity is to use the satellite agility in order to align the ground projection of the scanline on the ground velocity. This weird viewing principle allows all the detectors to view the same landscape. Thus, non-linear normalization coefficients can be computed by a histogram matching method. The goal of this paper is to present the Pleiades-HR non-linear normalization model, the suited steered mode and the method to compute the coefficients within Pleiades-HR context.

Abstract: Most of the three-dimensional (3-D) reconstructions of human organs rely on medical volume data. In this paper, we propose to use the endoscopic image sequences as a new image modality for surface reconstruction of human organs or tissues. Using the pinhole camera model, the original 3-D points are projected to two-dimensional (2-D) images by multiplying transformation matrices. We assume the intrinsic camera parameters, such as the focal length and principal points, are known and simplify the transformation matrices to only include the camera motion, i.e. camera rotation and translation. Using the factorization method for recovering the shape of the object and the motion of the camera from an image sequence, the 3-D structures are computed. 3-D reconstruction from endoscopic image sequences is a new exploration. It provides additional information that facilitates the understanding for the lesion areas three-dimensionally. And the reconstructed structures directly correspond to the original images and can be rendered with precise texture-mapping easily. It has potential to be used to guide surgery and serve as an alternative data source for constructing new stereo endoscopy systems using one camera.

Abstract: It is generally believed that very fast cameras imaging large Fields of View translate into huge optomechanics and mosaics of very large contiguous CCDs. It has already been suggested that seeing limited imaging cameras for telescopes whose diameters are larger than 20m are considered virtually impossible for a reasonable cost. We show here that, using existing technology and at a moderate price, one can build a Smart Fast Camera, a device that placed on aberrated Field of View, including those of slow focal ratios, is able to provide imaging at an equivalent focal ratio as low as F/1, with a size that is identical to the large focal ratio focal plane size. The design allows for easy correction of aberrations over the Field of View. It has low weight and size with respect to any focal reducer or prime focus station of the same performance. It can be applied to existing 8m-class telescopes to provide a wide field fast focal plane or to achieve seeing-limited imaging on Extremely Large Telescopes. As it offers inherently fast read-out in a massive parallel mode, the SFC can be used as a pupil or focal plane camera for pupil-plane or Shack-Hartmann wavefront sensing for 30-100m class telescopes.

Abstract: We present an adaptive optical closed loop system to obtain a good focused beam. A bimorph mirror is used as a wavefront corrector and CCD camera at the focal plane of the lens is a sensor. Such adaptive system can correct for the low-order wavefront aberrations without any sophisticated wavefront sensors.

Abstract: Method for 3D contactless optical measurement of object surfaces using an optical image sensor (3) for 2D image detection. The method involves recording images at a focal plane position (Fz) in a third z direction. The depth of the focal plane is very small. A series of images is recorded to create an image stack from which the 3D image is created. An independent claim is made for a coordinate measurement device with a camera for recording 2D image sets that are combined to form a 3D image for coordinate measurement.

Abstract: The paper presents a concept of a smart pushbroom imaging system with compensation of attitude instability effects. The compensation is performed by active opto-mechatronic stabilization of the focal plane image motion in a closed loop system with visual feedback on base of an auxiliary matrix image sensor and an onboard optical correlator. In this way the effects of the attitude instability, vibrations and micro shocks can be neutralized, the image quality improved and the requirements to satellite attitude stability reduced. To prove the feasibility and to estimate the effectiveness of the image motion stabilization, a performance model of the smart imaging system has been developed and a simulation experiment has been carried out. The description of the performance model and the results of the simulation experiment are also given.