The ICF program at Livermore has a large inventory of optical streak cameras that were built in the 1970s and 1980s. The cameras include microchannel plate image-intensifier tubes (IIT) that provide signal amplification and early lenscoupled CCD readouts. Today, these cameras are still very functional, but some replacement parts such as the original streak tube, CCD, and IIT are scarce and obsolete. This article describes recent efforts to improve the performance of these cameras using today’s advanced CCD readout technologies. Very sensitive, large-format CCD arrays with efficient fiber-optic input faceplates are now available for direct coupling with the streak tube. Measurements of camera performance characteristics including linearity, spatial and temporal resolution, line-spread function, contrast transfer ratio (CTR), and dynamic range have been made for several different camera configurations: CCD coupled directly to the streak tube, CCD directly coupled to the IIT, and the original configuration with a smaller CCD lens coupled to the IIT output. Spatial resolution (limiting visual) with and without the IIT is 8 and 20 lp/mm, respectively, for photocathode current density up to 25% of the Child-Langmuir (C-L) space-charge limit. Temporal resolution (fwhm) deteriorates by about 20% when the cathode current density reaches 10% of the C-L space charge limit. Streak tube operation with large average tube current was observed by lluminating the entire slit region through a Ronchi ruling and measuring the CTR. Sensitivity (CCD electrons per streak tube photoelectron) for the various configurations ranged from 7.5 to 2,700 with read noise of 7.5 to 10.5 electrons. Optimum spatial resolution is achieved when the IIT is removed. Maximum dynamic range requires a configuration where a single photoelectron from the photocathode produces a signal that is 3 to 5 times the read noise.

In the plasma flash x-ray generator, high-voltage main condenser of about 200 nF is charged up to 55 kV by a power supply, and electric charges in the condenser are discharged to an x-ray tube after triggering the cathode electrode. The flash x-rays are then produced. The x-ray tube is of a demountable triode that is connected to a turbo molecular pump with a pressure of approximately 1 mPa. As electron flows from the cathode electrode are roughly converged to a rod cerium target of 3.0 mm in diameter by electric field in the x-ray tube, the weakly ionized linear plasma, which consists of cerium ions and electrons, forms by target evaporating. At a charging voltage of 55 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 20 kA. When the charging voltage was increased, weakly ionized cerium plasma formed, and the K-series characteristic x-ray intensities increased. The x-ray pulse widths were about 500 ns, and the time-integrated x-ray intensity had a value of about 40 μC/kg at 1.0 m from x-ray source with a charging voltage of 55 kV. In the angiography, we employed a film-less computed radiography (CR) system and iodine-based microspheres. Because K-series characteristic x-rays are absorbed easily by the microspheres, high-contrast angiography has been performed.

Air Force Research Laboratory and MetroLaser, Inc. researchers have completed the initial development and transition to operational use of portable field holography systems. This paper documents the first fully operational use of a novel and unique experimental capability for remote field holography. In this paper we document the field trials and initial experiments that were performed with the Remote Holographic Interferometry System (RHIS) at the Munitions Directorate, Air Force Research Laboratory Site at Eglin, AFB, Florida. These experiments were performed to assess the effectiveness of remote pulsed laser holography combined with high-speed videography to document the formation and propagation of plumes of materials created by impact of high-speed projectiles. This paper details the development of the experimental procedures and initial results of this new tool.

The use of diffuse and line of sight optical radiation for wireless communications is an area of growing interest. In diffuse optical communications systems, light takes multiple paths from source to detector. Therefore knowledge of these multipaths is crucial to design of communications systems. In order to measure the characteristics of the optical channels a novel imaging system that records the frequency response of the indoor optical channel has been developed. The system uses a swept frequency laser source to illuminate the room and a large aperture telescope that concentrates incoming radiation onto a photomultiplier to receive it. Scanning of the receiver telescope yields data for all angles of arrival, allowing the angle-dependent frequency response to be obtained. Subsequent processing, using Fourier transform or superresolution techniques yields images of the arriving optical multipaths. In this paper the construction and characteristics of the imaging system are introduced. Frequency response measurements of a particular space, up to 750MHz, corresponding to approximately 1.5ns time resolution, are presented, together with images of light propagating within the coverage area.

We report the analysis and application of uncooled, directly-modulated high-speed DFB lasers with emphasis on their analogue transmission performance. Fibre-optic links employing such lasers are shown to meet the most stringent requirements of analogue systems at both high carrier frequencies and high temperatures. Spurious-free dynamic ranges (SFDR) exceeding 100dB×Hz^2/3 and 90dB×Hz^2/3 and input third-order intercept points (IIP3) above 20dBm and 18dBm are reported for carrier frequencies up to 20GHz at 25°C and up to 10GHz at 85°C, respectively. The error-vector magnitude (EVM) for a 256-QAM modulated signal transmitted over 15km of SMF remains below 1.9% for carrier frequencies of both 2GHz and 5GHz for all measured temperatures. The link performance is assessed by using 3GPP W-CDMA, IEEE 802.11a and IEEE 802.11b signals. In all cases the EVM remains within the standard specification, for fibre-optic link lengths of up to 10km and laser operating temperatures of up to 70°C. Finally, an IEEE 802.11b WLAN demonstrator is presented, allowing antenna remoting over up to 1000m of 62.5/125μm MMF.

This paper describes the architecture, process technology, and performance of a family of high burst rate CCDs. These imagers employ high speed, low lag photo-detectors with local storage at each photo-detector to achieve image capture at rates greater than 10⁶ frames per second. One imager has a 64 x 64 pixel array with 12 frames of storage. A second imager has a 80 x 160 array with 28 frames of storage, and the third imager has a 64 x 64 pixel array with 300 frames of storage. Application areas include capture of rapid mechanical motion, optical wavefront sensing, fluid cavitation research, combustion studies, plasma research and wind-tunnel-based gas dynamics research.

An image sensor acquisition and readout circuit prototype, capable of 4 to 10 million frames/s and 79 dB (13 bits), RMS, dynamic range has been fabricated and tested. The 0.35 μm CMOS chip tests sensor and readout circuitry intended for applications such as accelerator-based radiography, where fast, brief, transient events can be captured with high resolution. It exhibits a unique combination of extremely high speeds and very wide dynamic range, as well as 64-frame analog storage on the focal plane array (FPA). Each pixel includes either a charge-integrating trans-impedance amplifier or a direct-integration source-follower front end, followed by an array of 64 sample capacitors and associated readout electronics. Flexible operation capabilities allows the acquisition of either 32 frames using correlated double sampling (CDS) at 4 M-frames/s, or 64 frames without CDS at 7 M-frames/s without any reduction in gain. Allowing a -3dB gain reduction, frame rates as high as 10.5 MHz can be achieved. CDS is performed by acquiring two samples per frame, one immediately after reset and one at the end of the integration period, followed by external subtraction of the two samples. Two samples at a time are read out in parallel when CDS is not required. A 200 by 200 μm pixel is implemented in order to mate an extended version to an existing back-illuminated hybrid photo-diode FPA.

A pixel-parallel image sensor readout technique is demonstrated for CMOS active pixel sensors to facilitate a range of applications where the high-speed detection of the presence of an object, such as a laser spot, is required. Information concerning the object’s location and size is more relevant that a captured image for such applications. A sensor for which the output comprises the numbers of pixels above a global threshold in both rows and columns is demonstrated in 0.18 μm CMOS technology. The factors limiting the ultimate performance of such a system are discussed. Subsequently, techniques for enhancing information retrieval from the sensor are introduced,including centroid calculations using multiple thresholds, multi-axis readout, and run-length encoding.

High-performance color image acquisition has heretofore relied on color video cameras using multiple image sensors mounted on spectral separation prisms to provide geometrically accurate color data free of reconstruction artifacts. Recently, a CMOS image sensor has been developed that incorporates three complete planes of photodiodes in a single device to provide color separation without the need for external optical elements. The first commercial device based on this technology has 1512 x 2268 three-color photosites on 9.12 micron centers and includes provisions for combining pixels in X and Y, region-of interest selection and sparse scanning. The camera described in this paper operates the sensor in a variety of scan modes offering tradeoffs between resolution, coverage and speed. In this camera, a 128x128 raster of either a matrix of this size or binned from a large area can be scanned at nearly 150 frames per second and a single 2048-element line can be scanned at 7 KHz. At full resolution, the image sensor will acquire four frames per second. The scan configuration can be reloaded in less than 50 microseconds permitting mod e changes on the fly.

With the advent of large digital image files in the high speed imaging in the range test environment comes the opportunity and the requirement to establish a comprehensive archiving system. This system should provide a means for handling multiple image formats, film, video and digital and also audio and documentary data. It should have the ability to transfer complete project data packages in a digital form for central storage and for transfer between ranges. This paper lays out the requirements with the intent of soliciting user input.

Theoretical model of a new high-speed metal - insulator - semiconductor (MIS) radiation sensor possessing giant internal signal amplification is proposed to describe the experimentally obtained results. The sensor is fabricated on an Ultra-High Resistivity (UHR) Epi Layer (>10 kΩ cm) on a heavily doped wafer. Theoretical modeling explains the giant value of the internal amplification of the signal that is determined as the ratio of peak values of readout currents and instantaneous photo current. At the integration time about 1 sec the amplification coefficient is of the order of 10⁴ in the case of the external load 10 - 50 kΩ, and it is of the order of 10⁶ when the external load is smaller than 1 kΩ. The sensors operate under non-modulated radiation as well as under an optical signal modulation till 1 GHz.

Transporting MPEG-4 video over the Internet is expected to be an important component of many multimedia applications. The ISMA (Internet Streaming Media Alliance) has defied two hierarchical profiles to stream video content on wireless and narrow band networks, and over broadband quality networks. The evaluation mechanisms to assess the quality of video will play a major role in the overall design of video communication. However, the ISMA (Internet Streaming Media Alliance) MPEG-4 video quality analysis has not been reported. This paper presents statistical video quality analysis for the ISMA MPEG-4 video clips. Shannon entropies and principle components are used to interpret the degraded video quality in video sequences. Moreover, the current trends in error resilient video coding techniques and the error control/resilience solutions will be discussed.

We purpose a new design configuration of a phase modulated mode-locked figure eight laser(F8L)with two EDFAs and experimentally measure its characteristics in this paper. Our designed F8L mode-locked laser concludes two EFDAs, an isolator, a phase modulator(PM), two polarization controllers(PC)and two unbalance couplers(90:10). Two PCs are put at the input and output of two EDFAs to fix the polarization of light to generate a stable mode-locking laser output. A nonlinear loop mirror(NLM) is used to make the pulse being compressed. The PM can add an RF modulation signal to help mode-locking of the ultrashort pulse. Preliminary experimental demonstration is given in this paper. We present the time relative responses of this system for high speed photography triggering.

The aim of this research is to recompress the JPEG standard images in order to minimize the storage and/or communications bandwidth requirements. In our approach, we convert existing JPEG images into JPEG 2000 images. The proposed image restoration method is applied to improve the visual quality when the bit rate becomes low and visually annoying artifacts appear in existing JPEG image. The JPEG restoration algorithm here makes use of the DCT quantization noise model along with a Markov random field (MRF) prior model for the original image in order to formulate the restoration algorithm in a Bayesian framework. The maximum of a posteriori (MAP) principle based convex model is applied to restore images. The restored image is then compressed with the JPEG2000. The cumulative distribution function (CDF) based visual quality metric method has been developed to measure coding artifacts in large JPEG images. Perceptual distortion analysis is also included in this paper.

Studies have revealed that the variation of the normalized photon number of a single-cycle pulse (SCP) with the phase *Φ can be expressed in the form of {1+F*cos(2*Φ)}. Analytical expressions of F-functions in terms of the pulse width have been derived for analytical pulses of different profiles. Considering the fact that, for a train of mode-locked pulses, the phase may change from pulse to pulse, it can be shown that the duration and phase of SCPs can be evaluated with the aid of a square-law photodetector.

Flows over double cones and wedges featured with a large shock induced separation zone are representative of many parts of hypersonic vehicle geometries. To be practically important at shock interactions is phenomena that the shock wave produced from another objects carries out incidence to bow shock around a blunt body in the hypersonic flows, the two shock waves interact each other and various shock interactions occur according to the intensity of the shock wave and depending on the case of the local maximum of pressure and heat flux is locally produced on the body surface. The six types of shock interactions are classified, and particularly in the Type IV, a shear layer generated from the intersection of the two shock reached on the body surface, and locally anomalous pressure increase and aerodynamic heating occurred experimentally. In the present study, unsteady shock oscillations and periodically separation flows were visualized by means of high-speed video camera. Particularly, sequential observations with combination of schlieren methods are very effective because of flow unsteadiness.

A camera for ultra-fast motion measurement based on tomographic techniques is presented. The motion analysis is performed by following the movements of several discrete points (light emitting sources) positioned on the object. The camera utilizes three linear detectors, and the optical system is designed so that the measurements on the linear detectors are projections of the two-dimensional image. Using a suitable reconstructing algorithm based on discrete tomographic techniques, the position of the original point sources on the virtual two-dimensional image is determined. The remaining ambiguity of the tomographic reconstruction is minimized by assuming a model for the intensity of the point sources and adopting a normalization algorithm. The realization of this principle requires a rather sophisticated optical system to realize the one-dimension projection of the whole field of view without introducing significant aberrations, and three such optical systems in parallel are necessary to realize the tomographic reconstruction. In addition, these optical systems have to guarantee some depth of focus to allow reconstruction of movements also along the line of sight. Here we present the design of a camera based on this principle that can be operated at frame rates up to 40 KHz; it has a 30° field-of-view diameter and focuses objects at 2 m distance with spatial resolution of about 1.5 mm over a 1.1 m depth of focus length.

A 512x512-element, multi-frame charge-coupled device (CCD) has been developed for collecting four sequential image frames at megahertz rates. To operate at fast frame rates with high sensitivity, the imager uses an electronic shutter technology developed for back-illuminated CCDs. Device-level simulations were done to estimate the CCD collection well spaces for sub-microsecond photoelectron collection times. Also required for the high frame rates were process enhancements that included metal strapping of the polysilicon gate electrodes and a second metal layer. Tests on finished back-illuminated CCD imagers have demonstrated sequential multi-frame capture capability with integration intervals in the hundreds of nanoseconds range.