Kevin L. Albright

Construction and characterization of partial digest DNA libraries made from flow-sorted human chromosome 16☆

In this report, we present the techniques used for the construction of chromosome-specific partial digest libraries from flow-sorted chromosomes and the characterization of two such libraries from human chromosome 16. These libraries were constructed to provide materials for use in the development of a high-resolution physical map of human chromosome 16, and as part of a distributive effort on the National Laboratory Gene Library Project. Libraries with 20-fold coverage were made in Charon-40 (LA16NL03) and in sCos-1 (LA16NC02) after chromosome 16 was sorted from a mouse-human monochromosomal hybrid cell line containing a single homologue of human chromosome 16. Both libraries are approximately 90% enriched for human chromosome 16, have low nonrecombinant backgrounds, and are highly representative for human chromosome-16 sequences. The cosmid library in particular has provided a valuable resource for the isolation of coding sequences, and in the ongoing development of a physical map of human chromosome 16.

High-speed test station for solid state imagers

A PC-based programmable solid-state imager test station has been designed and is in final development phases. It is designed to provide a flexible universal high-speed platform for evaluation of different imager designs and formats including various multiport configurations. The system provides drive and acquisition circuitry and components to allow electro-optic characterization of imagers as a function of pixel readout rate. The data are scan-converted to RS-170 format for analysis. The systems functional capabilities and performance are presented. Examples of program code to generate three phase clocks for an 8-port Frame Transfer EEV CCD are included. A sampling of preliminary results obtained from variable rate clocking of this imager are discussed.

Intensified/shuttered cooled CCD camera for dynamic proton radiography

An intensified/shuttered cooled PC-based CCD camera system was designed and successfully fielded on proton radiography experiments at the Los Alamos National Laboratory ALNSCE facility using 800-MeV protons. The four camera detector system used front-illuminated full-frame CCD arrays fiber optically coupled to either 25-mm diameter planar diode or microchannel plate image intensifiers which provided optical shuttering for time resolved imaging of shock propagation in high explosives. The intensifiers also provided wavelength shifting and optical gain. Typical sequences consisting of four images corresponding to consecutive exposures of about 500 ns duration for 40-ns proton burst images separated by approximately 1 microsecond were taken during the radiography experiments. Camera design goals and measured performance characteristics including resolution, dynamic range, responsivity, system detection quantum efficiency, and signal-to-noise will be discussed.

High-frame-rate digital radiographic videography

High speed x-ray imaging can be an important tool for observing internal processes in a wide range of applications. In this paper we describe preliminary implementation of a system having the eventual goal of observing the internal dynamics of bone and joint reactions during loading. Two Los Alamos National Laboratory (LANL) gated and image intensified camera systems were used to record images from an x-ray image convertor tube to demonstrate the potential of high frame-rate digital radiographic videography in the analysis of bone and joint dynamics of the human body. Preliminary experiments were done at LANL to test the systems. Initial high frame-rate imaging (from 500 to 1000 frames/s) of a swinging pendulum mounted to the face of an X-ray image convertor tube demonstrated high contrast response and baseline sensitivity. The systems were then evaluated at the Motion Analysis Laboratory of Henry Ford Health Systems Bone and Joint Center. Imaging of a 9 inch acrylic disk with embedded lead markers rotating at approximately 1000 RPM, demonstrated the system response to a high velocity/high contrast target. By gating the P-20 phosphor image from the X-ray image convertor with a second image intensifier (II) and using a 100 microsecond wide optical gate through the second II, enough prompt light decay from the x-ray image convertor phosphor had taken place to achieve reduction of most of the motion blurring. Measurement of the marker velocity was made by using video frames acquired at 500 frames/s. The data obtained from both experiments successfully demonstrated the feasibility of the technique. Several key areas for improvement are discussed along with salient test results and experiment details.

CCD operation using the High Speed Imager Test Station

The use of a high-speed (up to 100 MHz) programmable pattern generator and special clock driver/translator circuits for clocking solid-state multiple output imagers is discussed. A specific example of clocking a developmental 256 X 512 two-port CCD is illustrated. Reference to a prior report of clocking an eight-port CCD is included. Future use in clocking a CID imager is discussed.

High-frame-rate CCD cameras with fast optical shutters for military and medical imaging applications

Los Alamos National Laboratory (LANL) has designed and prototyped high-frame rate intensified/shuttered Charge-Coupled-Device (CCD) cameras capable of operating at Kilohertz frame rates (non-interfaced mode) with optical shutters capable of acquiring nanosecond-to- microsecond exposures each frame. These cameras utilize an Interline Transfer CCD, Loral Fairchild CCD-222 with 244 (vertical) X 380 (horizontal) pixels operated at pixel rates approaching 100 Mhz. Initial prototype designs demonstrated single-port serial readout rates exceeding 2.97 Kilohertz with greater than 5 lp/mm spatial resolution at shutter speeds as short as 5 ns. Readout was achieved by using a truncated format of 128 X 128 pixels by partial masking of the CCD and then subclocking the array at approximately 65 Mhz pixel rate. Shuttering was accomplished with a proximity focused microchannel plate (MCP) image intensifier (MCPII) that incorporated a high strip current MCP (28 uA/sq.cm) and a LANL design modification for high-speed stripline gating geometry to provide both fast shuttering and high repetition rate capabilities. Later camera designs use a close-packed quadrupole head geometry fabricated using an array of four separate CCDs (pseudo 4-port device). This design provides four video outputs with optional parallel or time-phased sequential readout modes. Parallel readout exploits the full potential of both the CCD and MCPII with reduced performance whereas sequential readout permits 4X slower operation with improved performance by multiplexing, but requires individual shuttering of each CCD. The quad head format was designed with flexibility for coupling to various image intensifier configurations, including individual intensifiers for each CCD imager, a single intensifier with fiber optic or lens/prism coupled fanout of the input image to be shared by the four CCD imagers or a large diameter phosphor screen of a gateable framing type intensifier for time sequential relaying of a complete new input image to each CCD imager. Camera designs and their potential use in ongoing military and medical time-resolved imaging applications are discussed.

Multiport solid-state imager characterization at variable pixel rates

The imaging performance of an 8-port Full Frame Transfer Charge Coupled Device (FFT CCD) as a function of several parameters including pixel clock rate is presented. The device, model CCD-13, manufactured by English Electric Valve (EEV), is a 512 X 512 pixel array designed with four individual programmable bidirectional serial registers and eight output amplifiers permitting simultaneous readout of eight segments (128 horizontal X 256 vertical pixels) of the array. The imager was evaluated in Los Alamos National Laboratorys High-Speed Solid-State Imager Test Station at true pixel rates as high as 50 MHz for effective imager pixel rates approaching 400 MHz from multiporting. Key response characteristics measured include absolute responsivity, Charge-Transfer-Efficiency (CTE), dynamic range, resolution, signal-to-noise ratio, and electronic and optical crosstalk among the eight video channels. Preliminary test results and data obtained from the CCD-13 are presented and the versatility/capabilities of the test station are reviewed.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Rate effects of standard and high-strip-current microchannel plate image intensifiers

The gains of gated MCPIIs at high repetition rate (up to 10 kHz) were measured. Comparisons were made between the gain behavior of a standard ITT type F4111 MCPII and similar device incorporating a high strip current microchannel plate. The most notable effect observed for the standard MCPII is a decline in luminous gain with increasing gate repetition rate and with higher input irradiances. The intensifier with the higher strip current microchannel plate (MCP), on the other hand, exhibited little or no reduction in gain for gating frequencies up to 10 kHz under similar test conditions (60 pJ/cm2 input energy density). The charge storage capacity and recharge time of the standard MCPII are most likely the limiting factors in its ability to maintain a constant gain at high repetition rates. The limiting effect of the recharge time on the MCP gain is calculated and compared to the actual measurements.

Avalanche photodiode array sensor with high-speed CCD delay line readout

A prototype solid-state multi-chip-module (MCM) optical sensor circuit is described. The MCM is designed to sample the optical signals from a fiber-optic array at rates up to 200 MHz. The fiber-optic inputs interface to the MCM avalanche-photodiode (APD) sensor array. The prototype 40 pixel MCM stores approximately 1000 samples from each fiber before readout. This is done on the MCM using high-speed charge-injection input CCD delay line ICs. The MCM is designed to be cooled to 0 degrees C. This stabilizes the APD gain and minimizes dark current generation in the APD and the CCD delay line.

High-speed camera with a back-thinned 16-port frame transfer CCD sensor

A high frame rate CCD camera is described, based on the a new, back-thinned, 512/spl times/512 pixel frame transfer sensor with 16 video ports. The sensor allows for imaging beyond the visible range within a large dynamic range. Circuits for testing and evaluation of the sensor over a large range of charge transfer clock frequencies and the measured data are presented. The performance of the device when driven to the readout speed limit is also discussed.<<ETX>>