Abstract: Imaging polarimetry has the potential to be a key sensor technology in a number of target detection applications. Imaging polarimeters measure the polarization state of light emitted from and/or reflected from scenes. The light is polarized because of the geometry, roughness and material properties of the objects embedded in the scene. This added information enhances conventional intensity and color imagery, potentially surpassing its performance in low contrast situations. In this paper, we describe a divided aperture MWIR imaging polarimeter which acquires multiple polarization images simultaneously. At the heart of the polarimeter is a relay lens set that produces four identical images on a single focal plane array from a single aperture. Each of the four images measures a different orientation of linear polarization, 0, 45, 90 and 135 degrees. The relay lens set operates inside of a pour fill Dewar of a InSb MWIR camera. The design and calibration method for the polarimeter are given along with example data sets taken from the air over Huntsville, AL.

Abstract: Helico-conical optical beams, different from higher-order Bessel beams, are generated with a parallel-aligned nematic liquid crystal spatial light modulator (SLM) by multiplying helical and conical phase functions leading to a nonseparable radial and azimuthal phase dependence. The intensity distributions of the focused beams are explored in two- and three-dimensions. In contrast to the ring shape formed by a focused optical vortex, a helico-conical beam produces a spiral intensity distribution at the focal plane. Simple scaling relationships are found between observed spiral geometry and initial phase distributions. Observations near the focal plane further reveal a cork-screw intensity distribution around the propagation axis. These light distributions, and variations upon them, may find use for optical trapping and manipulation of mesoscopic particles.

Abstract: A plurality of temperature dependent focal plane arrays operate without a temperature stabilization cooler and/or heater over a wide range of ambient temperatures. Gain, offset and/or bias correction tables are provided in a flash memory in memory pages indexed by the measured temperature of the focal plane arrays. The memory stores a calibration database, which is accessed using a logic circuit which generates a memory page address from a digitized temperature measurement of each of the focal plane array. The calibration database is comprised of an array of bias, gain and offset values for each pixel in the focal plane array for each potential operating temperature over the entire range of potential operating temperatures. The bias, gain and offset data within the database are read out, converted to analog form, and used by analog circuits to correct the focal plane array response. The output of each of the FPAs is multiplexed to a shared processing module and calibration data for each of the FPAs is accessed from the shared processing module.

Abstract: An addressable array of lenses is disclosed. Two electrical connections per row address specific lenses within that row. Carriages support individual lenses, and from each resonant units with frequencies that are unique within each row. A voltage, having the same frequency as a selected resonant unit, is applied. The selected lens produces a resonating image. Testing has verified proper resonance addressing within a 5-by-5 array of microlenses. The array can be applied to a Shack-Hartmann (SH) sensor. To compensate for errant focal points outside of their assigned area, resonating images are identified by a processor. The array thus improves the dynamic range of wavefront aberration that can be measured by the SH sensor. The inventors currently estimate the improvement over conventional SH designs to be about a factor of 30.

Abstract: Two novel objective types on the basis of artificial compound eyes are examined. Both imaging systems are well suited for fabrication using microoptics technology due to the small required lens sags. In the apposition optics a microlens array (MLA) and a photo detector array of different pitch in its focal plane are applied. The image reconstruction is based on moire magnification. Several generations of demonstrators of this objective type are manufactured by photo lithographic processes. This includes a system with opaque walls between adjacent channels and an objective which is directly applied onto a CMOS detector array. The cluster eye approach, which is based on a mixture of superposition compound eyes and the vision system of jumping spiders, produces a regular image. Here, three microlens arrays of different pitch form arrays of Keplerian microtelescopes with tilted optical axes, including a field lens. The microlens arrays of this demonstrator are also fabricated using microoptics technology, aperture arrays are applied. Subsequently the lens arrays are stacked to the overall microoptical system on wafer scale. Both fabricated types of artificial compound eye imaging systems are experimentally characterized with respect to resolution, sensitivity and cross talk between adjacent channels. Captured images are presented.

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: PROBLEM TO BE SOLVED: To synthesize, from data obtained through one photography, an image that is focused at a certain distance after the photography. SOLUTION: An image synthesis method is applied to an image pickup apparatus having a plurality of positive lenses 12 arranged two-dimensionally in the vicinity of the focal plane of an imaging optical system 11, and image pickup elements 13 disposed on the backs of the plurality of positive lens and each comprising a plurality of two-dimensionally arranged pixels (a, b, c, d, e) having a photoelectric conversion function. The apparatus receives beams of light from different regions of the exit pupil of the imaging optical system 11 for each of the pixels. Based on the pixel outputs of the image pickup elements 13, the image data of an image on a certain image plane of the imaging optical system are synthesized. The image data Ia, Ib, Ic, Id, Ie formed by the respective pixels (a, b, c, d, e) are arranged in an overlapping, staggered manner such that they do not match one another by an amount equal to the height of the plane, whereby the image data of an image I' can be synthesized. COPYRIGHT: (C)2007,JPO&INPIT

Abstract: An illumination apparatus includes a reflector including a parabolic or ellipsoidal mirror, a light source arranged near a (first) focal point of the reflector, and a front mirror having a transparent window and a mirror surface symmetrical about the light axis. Luminous flux emitted from the light source is reflected from the reflector. In the case of the parabolic mirror, the front mirror has the same size as an entrance of an output light utilizing optical system, and the luminous flux exits toward the optical system as collimated light. In the case of the ellipsoidal mirror, the front mirror is arranged between two focal points of the ellipsoidal mirror, and the luminous flux is directed toward the second focal point. However, at least one part of the luminous flux is reflected from the front mirror and returned toward the first focal point.

Abstract: A digital keystone correction process locates image points in a corrected image from image points in a distorted image that was produced by misalignment of the axis of a sensor such as a camera The correction process locates corrected image points by constructing intercept points that are the intersections of the extended sides of a quadrilateral in the distorted image plane that is constructed from a known rectangular feature in the subject plane Reference points are located by drawing a line through each intercept point and the distorted image point Distances are found from the intercept points to the image points and the reference points The distances are scaled and corrected with an offset to locate the coordinates of the image points in the corrected image plane This process can correct alignment errors of pitch, yaw, and roll between the subject plane and an image plane such as photographic film

Abstract: An efficient image capture system is disclosed that integrates functions to control a lens including one or more of focus or object distance, zoom, temperature compensation, and stabilization within an image signal processor (ISP) with appropriate algorithms. In particular, the integrated ISP circuitry may control the motion of the focus and zoom optics of an optical assembly, control stabilization, control the flash, provide enhanced functions and features for controlling the zoom and focus lenses to enable enhanced image capture sequences and/or tracking lens data, provide a set of algorithms within the ISP to alter the aspect ratio (both height and width of an image) of the image, for example to compensate for the addition of an anamorphic lens, and integrate an anamorphic lens into the module to alter an image's projected aspect ratio onto the focal plane array.

Abstract: A wave-front sensing scheme based on placing a lenslet array at the focal plane of the telescope with each lenslet reimaging the aperture is analyzed. This wave-front sensing arrangement is the dual of the Shack–Hartmann sensor, with the wave front partitioned in the focal plane rather than in the aperture plane. This arrangement can be viewed as the generalization of the pyramid sensor and allows direct comparisons of this sensor with the Shack–Hartmann sensor. We show that, as with the Shack–Hartmann sensor, when subdividing in the focal plane, the quality of the wave-front estimate is a trade-off between the quality of the slope measurements over each region in the aperture and the resolution to which the slope measurements are obtained. Open-loop simulation results demonstrate that the performance of the lenslet array at the focal plane is equivalent to that of the Shack–Hartmann sensor when no modulation is applied to the lenslet array. However, when the array is modulated in a manner akin to that of the pyramid sensor, subdivision at the focal plane provides advantages when compared with the Shack–Hartmann sensor.

Abstract: We propose a configuration of an off-axis three-mirror system for maximum compactness and brightness. The chief ray is arranged to cross three times inside the system, and the system has a round configuration for compactness. We introduced into the design a ray triangle formed by the reflection points of the chief rays at the mirrors. The ray triangle indicates the size and the brightness of the system. Based on the proposed configuration, a design example of a 4 degrees x 4 degrees field of view is shown. The F-number of the system is 2.2, in close agreement with the estimation from the ray triangle.

Abstract: A system and method for calibration and compensation of a visual sensor system. The visual sensor system includes dark pixels adjacent active pixels on a CCD imaging array, which provide dark current data corresponding to image response data. Concurrently, the temperature of the focal plane of the CCD is measured by one or more temperature sensors disposed on the array. Concurrently, the temperature of a circuit board including a processor is measured by one or more temperature sensors arranged on the circuit board. The image response data, dark current data, and circuit board and focal plane temperatures are used to compensate the image response data.

Abstract: A novel detection pixel micro-structure allowing the simultaneous and continuous detection of several discrete optical frequencies. A focal plane array comprises a plurality of multi-spectral detection pixels and a connecting platform to electrically connect the pixels. Each of the multi-spectral detection pixels form a resonant optical structure that comprises at least two periodic latticed dielectric reflectors, and at least one optical cavity between the said latticed dielectric reflectors. The latticed dielectric reflectors create a plurality of photonic bandgaps in the spectral response of the pixel. In addition, each optical cavity of the pixel comprises at least two optical resonant modes, corresponding to localized Bloch modes supported by the pixel dielectric structure, wherein each optical resonant mode is localized maximally at, and minimally away from, the optical cavity.

Abstract: We propose a new scheme to generate a focusing hollow beam (FHB) by use of an azimuthally distributed 2pi-phase plate and a convergent thin lens. From the Fresnel diffraction theory, we calculate the intensity distributions of the FHB in free propagation space and study the relationship between the waist w_0 of the incident Gaussian beam (or the focal length f of the lens) and the dark spot size (or the beam radius) at the focal point and the relationship between the maximum radial intensity of the FHB and the dark spot size (or the beam radius) at the focal point, respectively. Our study shows that the FHB can be used to cool and trap neutral atoms by intensity-gradient-induced Sisyphus cooling due to an extremely high intensity gradient of the FHB itself near the focal point, or to guide and focus a cold molecular beam. We also calculate the optical potential of the blue-detuned FHB for ^85Rb atoms and find that in the focal plane, the smaller the dark spot size of the FHB is, the higher the optical potential is, and the greater the corresponding optimal detuning delta is; these qualities are beneficial to an atomic lens not only because it is profitable to obtain an atomic lens with a higher resolution, but also because it is helpful to reduce the spontaneous photon-scattering effect of atoms in the FHB.

Abstract: The Compressive Optical MONTAGE Photography Initiative (COMP-I) is an initiative under DARPA's MONTAGE program. The goals of COMP-I are to produce 1 mm thick visible imaging systems and 5 mm thick IR systems without compromising pixel-limited resolution. Innovations of COMP-I include focal-plane coding, block-wise focal plane codes, birefringent, holographic and 3D optical elements for focal plane remapping and embedded algorithms for image formation. In addition to meeting MONTAGE specifications for sensor thickness, focal plane coding enables a reduction in the transverse aperture size, physical layer compression of multispectral and hyperspectral data cubes, joint optical and electronic optimization for 3D sensing, tracking, feature-specific imaging and conformal array deployment.

Abstract: Presented is a new design method for distributed focal plane image processing, which allows complementary metal oxide semiconductor (CMOS) implementation of two-dimensional, reconfigurable, image-processing kernels at the pixel level.

Abstract: We describe multifocal multiphoton microscopy giving images without laser scanning. A multitude of 8 × 8 laser beams is focused into a sample yielding two-photon excitation in a plane. The focal spots are arranged in a rectangular array with close spacing between individual points (≈0.5 µm). The fluorescence emission from the sample is recorded with a CCD camera, but, owing to the close distance between the beams, they can no longer be regarded as individual points but rather as an illumination of the plane that is covered by the array of focal points. The axial sectioning capability is comparable with an ordinary single-beam two-photon microscope. Interference between the beams that could compromise the axial sectioning capability does not occur in our setup owing to small temporal delays between the individual beams. The axial sectioning capability of the setup is discussed in detail by means of the step response in which the foci are scanned axially into a uniformly fluorescent medium.

Abstract: It has been found that target optics produce non-specular, augmented optical returns when interrogated by a laser pulse. This non-specular radiation is detected by an active laser search system employing a direct-reading, thresholded focal plane detector that is able to detect non-cooperating targets with optics that employ a detector or optical element at the focal plane of their receiving optics. The pulses returned from such target optics have a width commensurate with the original transmitted pulse width, whereas passive background noise and the spread out active returns from the ground exhibit temporally long returns. By setting the sensor threshold sufficiently high, the system discriminates against noise and clutter while at the same time reducing the number of sweeps required to detect a target within the search area.

Abstract: An optical system for a riflescope (10) includes an objective element (11), an eyepiece element (17), an LD (12), an APD prism (130), an erector lens (15), an LED prism (160) and an LED panel (16). The erector lens is positioned between a first focal plane (18) and a second focal plane (19). The reticle is disposed at a distance of the second focal length so as to coincide with on the second focal plane. The LED prism is positioned between the erector lens and the second focal plane. The image of data of the range displayed by the LED panel is projected on the second focal plane through the LED prism. By this arrangement, the size and brightness of the reticle and the image of data of the range will not grow or shrink along with the target image size when the magnification is changed, and thus the shooter's vision feeling can be improved.

Abstract: The relationship between the size of a focal plane array in a prime focus dish and achievable scan angle is studied in order to find a starting point for designing such systems. A physical optics model is used to obtain focal plane fields and the radii in the focal plane required to encircle 3 dB and 1 dB below the incident power is calculated for a range of dish diameters and focal length over dish diameter ratios (F/D). The study found the focal plane fields are largely independent of dish size when the scan angle is expressed in beamwidths and gives guidance for the optimal F/D to achieve maximum field of view for a given focal plane array size.

Abstract: This paper describes an optical configuration for generating dual-focus from a single laser incident beam. The generated two foci have nearly equivalent spot size and both fall on the optical axis of the focusing optics, but at different focal lengths. The dual-focus optics allows for variations of the laser power of each focal point and the distance between the two focal points. The advantages of dual-focus ablation were demonstrated with a nanosecond UV laser dicing silicon substrates. The experimental results show that, compared to conventional single focus, dual-focus improves ablation rate by a factor of 2–4.

Abstract: In all-in-focus imaging, a series of photographs taken of the same objects, on different focal planes, are analyzed to create an entirely in-focus final image. Edge detection techniques determined by variable thresholds are applied to the 512x512 input images and they are then progressively subdivided into smaller, 2N sized blocks, varying in size from 256x256 pixels down to 1x1 pixel. The 1x1 blocks are used to determine actual edges and the areas around them are then filled with progressively larger block sizes. The particular image that is most in-focus over a given region is determined by comparing the sums of edge pixels for the corresponding blocks of the different input images. Beyond aesthetic value, all-in-focus imaging may be used in applications ranging from pattern recognition and object detection to biometrics. We have successfully detected in-focus regions in an image and have generated final, all-in-focus images with only minor errors.

Abstract: The intensity profile and beam caustics of a fiber coupled high power Nd:YAG laser beam through a lens system are studied. The thermal lensing effect and its influence on the beam profile and focal position are discussed. Asymmetry of the intensity profile in planes above and below the focal plane is demonstrated. Also the influence of small pollutions on the protective window is explained. Three different methods are used to measure the occurrence of thermal lensing and quantify these effects.

Abstract: Effects of diffraction of a spectral beam from an edge of the micromirrors are reduced in order to optimize the passband in a wavelength selective switch. The effects of diffraction on the pass band may be reduced by appropriate modification of the edges of the micromirrors, by modification of the input and/or output ports to allow for attenuation by rotation of the micromirror about the switching axis, by using rotation of the micromirror about both the attenuation axis and the switching axis to achieve the desired level of attenuation, by inserting an aperture at a focal plane or external to the device to reduce the magnitude of the micromirror edge diffraction transmitted to any or all output ports, or by appropriate filtering of angular frequencies with a diffraction grating used to separate a multi-channel optical signal into constituent spectral beams.

Abstract: A variational full-field method is presented in this paper for the free vibration analysis of open circular cylindrical laminated shells supported at discrete points. A differential equation in matrix form is developed using the first-order shear deformable theory of shells, and rotary inertia is included. The displacement fields are defined by using very high-order interpolating polynomials and a large number of preselected nodal points on the reference surface of the shell. Each nodal point has 5 degrees of freedom, three displacement components, and two components of the rotation of the normal to the reference surface. The stiffness and mass matrices are obtained using the strain and kinetic energy functions. The numerical results are calculated for shallow and deep circular cylindrical panels with four-, six-, and eight-point supports along the two parallel straight edges. The values of the natural frequency obtained from the present method show good agreement with published data in the literature.

Abstract: High-resolution imaging systems are provided In one embodiment, an imaging system based on a Cassegrain or Schmidt-Cassegrain objective, with coaxial primary and secondary mirrors, is provided with a microdisplacement mechanism acting on the secondary mirror to displace the image on a focusing array In another embodiment, two co-axial Cassegrain-type objectives are provided one within the other with a common focal plane array, which therefore detects combined wide field-of-view and narrow field-of-view images

Abstract: The observation of closely-spaced objects using limited-resolution Infrared (IR) sensor systems can result in merged object measurements on the focal plane. These Unresolved Closely-Spaced Objects (UCSOs) can significantly hamper the performance of surveillance systems. Algorithms are desired which robustly resolve UCSO signals such that (1) the number of targets, (2) the target locations on the focal plane, (3) the uncertainty in the location estimates, and (4) the target intensity signals are correctly preserved in the resolution process. This paper presents a framework for obtaining UCSO resolution while meeting tracker real-time computing requirements by applying processing algorithms in a hierarchical fashion. Image restoration techniques, which are often quite cheap, will be applied first to help reduce noise and improve resolution of UCSO objects on the focal plane. The CLEAN algorithm, developed to restore images of point targets, is used for illustration. Then, when processor constraints allow, more intensive algorithms are applied to further resolve USCO objects. A novel pixel-cluster decomposition algorithm that uses a particle distribution representative of the pixel-cluster intensities to feed the Expectation Maximization (EM) is used in this work. We will present simulation studies that illustrate the capability of this framework to improve correct object count on the focal plane while meeting the four goals listed above. In the presence of processing time constraints, the hierarchical framework provides an interruptible mechanism which can satisfy real-time run-time constraints while improving tracking performance.