Sensitivity Of Charge-coupled Device Research Articles

A Fully Integrated 0.055% INL X-ray CCD Readout ASIC with Incremental <inline-formula> <tex-math notation="LaTeX">$\Delta \Sigma {\text{ADC}}$</tex-math> </inline-formula>

A fully integrated 100 kHz X-ray charge coupled device (CCD) readout application specific integrated circuit (ASIC) employing delta sigma ( $\Delta \Sigma $ ) digitization is presented. To achieve high linearity with small chip size and low power consumption, the correlated double sampling (CDS) is realized by the $\Sigma \Delta{\rm ADC}$ instead of the analog front end (AFE) as in conventional CCD readout circuits. Besides, the proposed decimation filter features simple structure and eases the integration. The chip is fabricated in $0.35 \upmu\hbox{m}$ CMOS technology and the measured integral nonlinearity (INL) throughout the input dynamic range of ASIC is 0.055% with $35.1 \pm 0.3 \upmu\hbox{V}$ input referred noise. A CCD detection system is built and tested with the sensitivity of CCD being $4 \upmu\hbox{V}/\hbox{e}^-$ . The integration test results show that the readout noise is $11.8 \hbox{e}^ {-} $ at 100 kHz readout pixel rate and the achieved energy spectrum resolution is $168 \hbox{eV} \pm 4.7 \hbox{eV}$ (Full Width at Half Maximum: FWHM) at 5.9 keV.

Comparison of the accuracy of cone-beam computed tomography, photostimulable phosphor imaging plate, charge coupled device, and conventional intraoral radiography in the diagnosis of internal root resorption: an in vitro study

Objective: Various radiographic methods are used to identify the internal root resorption. The aim of this study was to assess and compare the diagnostic accuracy of cone-beam computed tomography (CBCT), photostimulable phosphor (PSP) imaging plate, charge coupled device (CCD), and conventional intraoral radiography (CIR), for internal root resorption.Methods: This experimental study was conducted in Hamadan in 2012. Fifty seven carries-free anterior teeth were divided into three intervention groups of 15 teeth and one control group of 12 teeth. Teeth were split into two parts using a disk. Cavities of 0.5, 1 and 1.5 mm in depth were created in root canal of teeth to simulate internal root resorption artificially. Finally, the teeth fragments were fused. All teeth were examined with four different procedures and the results were compared with known simulated internal root resorption as the gold standard to determine the sensitivity and specificity of the procedures.Results: The sensitivity of CBCT, PSP, CCD, and CIR for diagnosis internal root resorption of 0.5 mm in depth was 93%, 73%, 60%, and 53% respectively. The sensitivity of all four procedures for diagnosis of internal root resorption with 1 and 1.5 mm in depth was the same and equal to 100%. Specificity of the four radiology procedures for diagnosis of internal root resorption of any depth was 100%, 100%, 83% and 75% respectively.Conclusion: CBCT provides the most accurate information on the depth and location of root resorption followed by the PSP and CCD respectively. Accordingly, conventional intraoral radiography was the least accurate procedure.

A CMOS In-Pixel CTIA High-Sensitivity Fluorescence Imager

Traditionally, charge coupled device (CCD) based image sensors have held sway over the field of biomedical imaging. Complementary metal oxide semiconductor (CMOS) based imagers so far lack sensitivity leading to poor low-light imaging. Certain applications including our work on animal-mountable systems for imaging in awake and unrestrained rodents require the high sensitivity and image quality of CCDs and the low power consumption, flexibility and compactness of CMOS imagers. We present a 132×124 high sensitivity imager array with a 20.1 μm pixel pitch fabricated in a standard 0.5 μ CMOS process. The chip incorporates n-well/p-sub photodiodes, capacitive transimpedance amplifier (CTIA) based in-pixel amplification, pixel scanners and delta differencing circuits. The 5-transistor all-nMOS pixel interfaces with peripheral pMOS transistors for column-parallel CTIA. At 70 fps, the array has a minimum detectable signal of 4 nW/cm(2) at a wavelength of 450 nm while consuming 718 μA from a 3.3 V supply. Peak signal to noise ratio (SNR) was 44 dB at an incident intensity of 1 μW/cm(2). Implementing 4×4 binning allowed the frame rate to be increased to 675 fps. Alternately, sensitivity could be increased to detect about 0.8 nW/cm(2) while maintaining 70 fps. The chip was used to image single cell fluorescence at 28 fps with an average SNR of 32 dB. For comparison, a cooled CCD camera imaged the same cell at 20 fps with an average SNR of 33.2 dB under the same illumination while consuming over a watt.

Multi-purpose nonlinear optical microscope. Its principle and applications to polar thin-film observation

Multi-purpose nonlinear optical microscope is an optical microscope which images 2D distribution of the optical second harmonic (SH) waves from a specimen. Image contrast can be obtained either by inhomogeneous distribution of nonlinear optical tensor components or by the interference between SH waves from a specimen and a standard plate. This microscope also functions as a fl uorescence (FL) microscope, and SH and FL images can be obtained from same part of a specimen. Absorption and FL spectra from a specifi c part of a specimen are measured through an optical fi ber, which connects an ocular with a polychromator. These functions are especially useful to investigate the J-aggregate state of polar dye molecules. Several photographs taken by the microscope revealed the structure of merocyanine dye / arachidic acid mixed monolayer and the role of bridge ions in subphase. Experiments started in the 1970s for visualizing inhomogeneous distributions in a specimen using the second harmonic (SH) waves which the specimen produces [1,2]. Recent developments of the spatial resolution and sensitivity of Charge Coupled Device (CCD) camera and image processing techniques enable us to obtain more easily high quality images of various kinds of bulk materials and surfaces. We made good use of development of the technology and constructed a multinpurpose nonlinear optical microscope called SHCM and successfully applied it to observations of ferroelectric domain structures [3n5] and periodically inverted domain structures in quasinphase match devices for frequencynconverter [6]. Recently we have installed a Langmuir trough to the SHGM and performed innsitu observations of monolayer molecules at airnwater interface, in particular, those of the J-aggregate state of polar dye molecules. In this paper, we discuss the principle of the SHGM, describe its structure and show several photographs taken by the SHGM, emphasizing useful application to polar thin fi lm studies.