24,395 research outputs found
Breadboard linear array scan imager using LSI solid-state technology
The performance of large scale integration photodiode arrays in a linear array scan (pushbroom) breadboard was evaluated for application to multispectral remote sensing of the earth's resources. The technical approach, implementation, and test results of the program are described. Several self scanned linear array visible photodetector focal plane arrays were fabricated and evaluated in an optical bench configuration. A 1728-detector array operating in four bands (0.5 - 1.1 micrometer) was evaluated for noise, spectral response, dynamic range, crosstalk, MTF, noise equivalent irradiance, linearity, and image quality. Other results include image artifact data, temporal characteristics, radiometric accuracy, calibration experience, chip alignment, and array fabrication experience. Special studies and experimentation were included in long array fabrication and real-time image processing for low-cost ground stations, including the use of computer image processing. High quality images were produced and all objectives of the program were attained
Exploiting multimode waveguides for pure fibre-based imaging
We acknowledge support from the UK Engineering and Physical Science Research CouncilThere has been an immense drive in modern microscopy towards miniaturisation and fibre based technology. This has been necessitated by the need to access hostile or diffcult environments in-situ and in-vivo. Strategies to date have included the use of specialist fibres and miniaturised scanning systems accompanied by ingenious microfabricated lenses. We present a novel approach for this field by utilising disordered light within a standard multimode optical fibre for lensless microscopy and optical mode conversion. We demonstrate the modalities of bright-field and dark-field imaging and scanning fluorescence microscopy at acquisition rates allowing observation of dynamic processes such as Brownian motion of mesoscopic particles. Furthermore, we show how such control can realise a new form of mode converter and generate various types of advanced light fields such as propagation-invariant beams and optical vortices. These may be useful for future fibre based implementations of super-resolution or light sheet microscopy.Publisher PDFPeer reviewe
Focal Plane Alignment and Detector Characterization for the Subaru Prime Focus Spectrograph
We describe the infrastructure being developed to align and characterize the
detectors for the Subaru Measurement of Images and Redshifts (SuMIRe) Prime
Focus Spectrograph (PFS). PFS will employ four three-channel spectrographs with
an operating wavelength range of 3800 to 12600 . Each spectrograph
will be comprised of two visible channels and one near infrared (NIR) channel,
where each channel will use a separate Schmidt camera to image the captured
spectra onto their respective detectors. In the visible channels, Hamamatsu 2k
x 4k CCDs will be mounted in pairs to create a single 4k x 4k detector, while
the NIR channel will use a single Teledyne 4k x 4k H4RG HgCdTe device.Comment: 16 pages, 27 figures, SPIE ATI Montreal 201
Advanced smoke meter development survey and analysis
Ideal smoke meter characteristics are determined to provide a basis for evaluation of candidate systems. Five promising techniques are analyzed in detail to evaluate compilance with the practical smoke meter requirements. Four of the smoke measurement concepts are optical methods: Modulated Transmission (MODTRAN), Cross Beam Absorption Counter (CBAC), Laser Induced Incandescence (LIN), and Photoacoustic Spectroscopy (PAS). A rapid response filter instrument called a Taper Element Oscillating Microbalance (TEOM) is also evaluated. For each technique, the theoretical principles are described, the expected performance is determined, and the advantages and disadvantages are discussed The expected performance is evaluated against each of the smoke meter specifications, and the key questions for further study are given. The most promising smoke meter technique analyzed was MODTRAN, which is a variation on a direct transmission measurement. The soot-laden gas is passed through a transmission cell, and the gas pressure is modulated by a speaker
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