Hiding an image with a light-scattering medium and use of a contrast-discrimination method for readout

Hiding image data with a material such as a light-scattering medium is useful as an initial stage of data protection, because the hidden image can be detected only by observation with a specific technique. A light-scattering medium is used to hide the image data, and a low-temporal-coherence interferometer performs the readout processing. A new readout method for detecting pixel values of the image is proposed to overcome spatial variation of the light intensity and distortion of the interference fringes. The introduction of spatial coding further improves the performance by overcoming spatial variations of the light-scattering medium and variations in the reflectance of given pixels.     

Production and test of a readout chip for the ALICE SDD experiment

The paper summarizes the design, the fabrication and test of a chip for the silicon drift detector experiment, part of the A Large Ion Collider Experiment (ALICE) at CERN. The chip performs data reduction via bidimensional compression and packing for the readout chain of the experiment. The chip interfaces with front-end electronics and with the counting room. It is synchronized with a 40 MHz system master clock and configured via a serial signal. The work presents the tests that were performed to characterize the chip and it exploits the final yield of 89% over 700 fabricated chips. The whole tests were performed in laboratory and the chip was also tested in a test beam at CERN in November 2004.     

Design of a double-sided telecentric zoom lens

A method is presented for the calculation of paraxial design parameters of a double-sided telecentric zoom lens with easy variation of the magnification range. The telecentric lens consists of a zoom lens with a fixed distance between focal points and a lens with a fixed focal length. The third-order aberration analysis is also performed, and spot diagrams are calculated for two f-number values.     

Development of the central trigger system for the BELLE detector at the KEK B-factory

In this paper, we describe the design and development of the central trigger system (GDL) for the BELLE detector at the KEK B-factory. The GDL consists of four types of single width 6U VME modules (ITD, FTD, PSNM and TMD) which are designed using the programmable logic techniques of Xilinx FPGA and CPLD. Individual and combined performance tests of these modules are done and it is confirmed that the GDL functions as expected.     

Development of a fabrication technology for double-sided AC-coupled silicon microstrip detectors

We report on the development of a fabrication technology for double-sided, AC-coupled silicon microstrip detectors for tracking applications. Two batches of detectors with good electrical figures and a low defect rate were successfully manufactured at IRST Laboratory. The processing techniques and the experimental results obtained from these detector prototypes are presented and discussed.     

Development of a mos-CCD for parallel-in,serial-out readout

On behalf of CERN, Geneva, we are performing a feasibility study of a customer CCD circuit for a silicon microstrip detector readout [1]. In this presentation some design considerations will be discussed.     

Efficient computation of optical disk readout by use of the chirp z transform

Computation of the readout signal of an optical disk involves Fourier transforms from the objective lens pupil to the disk and, after interaction with the disk, from the disk to the objective pupil. Traditionally, the complex two-dimensional Fourier transform is numerically evaluated as a two-dimensional fast Fourier transform. To obtain sufficient resolution in the involved planes, one must choose sampling grid sizes of typically 1,024 x 1,024 or higher, resulting in a substantial computation time if the calculation is to be repeated many times. Discussed is an alternative method for evaluating the Fourier transform, based on the chirp z transform, by which a considerable improvement in efficiency can be obtained without loss of accuracy.     

Zigzag-shaped pads for cathode readout of a time projection chamber

We have introduced large zigzag-shaped pads for the cathode readout of a time projection chamber (TPC) to reduce the number of channels of readout electronics without degrading the spatial resolution. The spatial resolution has been studied using a laser. Zigzag-shaped pads are found to give a better spatial resolution than square pads of the same width for laser-beam tracks.     

Precise and simple optical alignment method for double-sided lithography

A method for aligning a photolithographic mask at the top of a transparent wafer that has a pattern on its bottom side is presented. The method is based on optical self-imaging of special alignment marks and provides submicrometer accuracy. The method is simple and robust and can conveniently be implemented on laboratory mask aligners for contact or proximity printing.     

Tunable four-pass narrow spectral bandwidth amplifier for use at approximately 508 nm

We report the implementation of a tunable, narrow-spectral-bandwidth, pulsed, four-pass dye-laser amplifier with strongly reduced amplified spontaneous emission. We present temporal pulse profiles, pulse spectra, and gain measurements of the amplifier output for the case of Coumarin 307 dye as the gain medium, seeded at wavelengths of approximately 508 nm and pumped at 355 nm.     

Beam test of the CsI(Tl) calorimeter for the BELLE detector at the KEK-B factory

We studied the performance of a prototype electromagnetic calorimeter for the BELLE detector at the KEK proton synchrotron for an energy range of 0.25–3.5 GeV. The prototype consisted of an array of 6 × 5 CsI(Tl) crystals with 30 cm length (16.2 radiation lengths) and about 6 cm × 6 cm cross section. The scintillation light of each CsI(Tl) crystal was read out by two large-area PIN photodiodes and charge-sensitive preamplifiers attached at the rear face of the crystal. We measured the energy and position resolution for electrons and the e/π separation for two sets of matrix configurations: one corresponded to the center and the other to the edge of the barrel calorimeter. The overall performance measured by the test proves that the prototype calorimeter is satisfactory for the use in the BELLE detector.     

Scanning electrochemical microscopy as a readout tool for protein electrophoresis

Scanning electrochemical microscopy (SECM) was used to image silver-stained proteins on a poly(vinylidene difluoride) membrane. The method is based on measuring the current at a scanning microelectrode in the feedback mode. The electrochemical feedback is caused by the redox-mediated etching of the isolated 5 - 10-nm-diameter silver nanoparticles formed during the staining process. Several parameters, such as the redox mediator and the staining protocol, were optimized to ensure a high resolution and a low detection limit, i.e., 0.5 ng of bovine serum albumin (4 x 10(-14) mol) distributed on an area of 1 mm(2) (4 x 10(-16) mol x cm(-2)). Images of beta-lactoglobulin A and myoglobin bands after gel electrophoretic separation and electroblotting were obtained in order to demonstrate that SECM can be employed as a sensitive and quantitative readout method for detection of proteins after gel electrophoresis. An additional advantage is that the silver staining can be removed, allowing further downstream mass spectrometry analysis.     

Performance of a BGO calorimeter with photodiode readout and with photomultiplier readout at energies up to 10 GeV

Bismuth germanate (BGO) calorimeter arrays, consisting of up to 12 elements of 30 × 30 × 200 mm³ have been tested at the CERN PS with pions and electrons of up to 10 GeV/c momentum, and at SIN with pions, electrons and protons up to 450 MeV/c. Both photomultiplier (PM) and photodiode (PD) readouts were used. Accurate calibration in the 100 MeV energy range was achieved with stopping protons, stopping pions and minimum ionizing pions. With 212 MeV electrons and PM readout, a time resolution of the BGO signal of 640 ps fwhm has been measured. The energy resolution for electrons above 1 GeV (PD readout) was found to be roughly constant at σ/E ～ 1%. This is consistent with a negligible intrinsic resolution for BGO at these energies, after taking into account shower leakage and PD noise. For electrons of 92 and 200 MeV, we obtained (PM readout) energy resolutions close to the theoretical limit given by photon statistics and shower leakage. The electron/hadron separation was better than 1:500 over the energy range of 0.5 to 10 GeV, and improved to better than 1:1000 after a simple pattern cut. The energy deposition of the e.m. showers, both laterally and longitudinally (rear leakage), was found to be in agreement at the 0.1% level with Monte Carlo calculations using the SLAC-EGS program.     

Time-to-charge converters for fast encoding and readout ADCs

Time-to-charge converters have been designed and built as front-end electronics for fast encoding and readout ADCs. The time resolution and long-term stability of these modules are both about 0.1% of the time range selected.     

Group-index and resonant field enhancement in a symmetric double-sided grated waveguide

A numerical study has been carried out by means of the Green's function method to explore possible performance improvements of a simple grated waveguide (GWg) by the variations of its grated structure. It is shown that a GWg featuring symmetric two-sided grated structure of 16 teeth with a 60?nm groove depth and having a symmetric refractive index profile with a relatively large contrast between the grated and ungrated layers is capable of delivering largely improved device performance compared to that achieved previously with a one-sided grating of 40?nm groove depth and asymmetric index profile. The improvement is characterized by a remarkable 8-fold and 15-fold increase in the group index and the maximum field intensity, respectively, at the first resonance wavelength above the upper band edge (shorter wavelength), while relatively less improvement is found at the first resonance wavelength below the lower band edge (longer wavelength). It is shown that more than 20% further improvement can be obtained by an appropriate shifting of the two innermost adjacent grating teeth in the case of the 40?nm groove depth. Apart from that, the result also reveals an interesting and remarkable correlation between the variations of the group index and the confined energy.     

Differential phase-contrast microscope with a split detector for the readout system of a multilayered optical memory

A transmission differential phase-contrast microscope with a split detector is used as a readout system for a multilayered three-dimensional optical memory. The system is applicable to data recorded as refractive-index changes. The system is compact and easy to use. The three-dimensional optical transfer function for the system is derived. This shows that the spatial bandwidth of the system is the same as that of a conventional microscope with incoherent illumination but with much improved contrast. Six layers of information are recorded in a photopolymer and are read out with little cross talk and high contrast.