Image detectors

To describe the X-ray imaging system the projection of 3D object points onto the 2D image plane, and nonlinear distortions inherent in the image detector system have to, be modelled. A parametric camera model based on a simple pinhole model to describe the projection in combination with a polynomal model of the nonlinear distortions is used to describe the X-ray imaging system. The parameters of the model are estimated using a two step approach. First the distortion parameters for fixed source and detector positions are calculated without any knowledge of the projection parameters. In a second step, the projection parameters are calculated for each image taken with the same source and detector positions but with different sample positions. 

In this section the camera model based on a projection model and the polynomal model of the image detector distortions will be described (figure 2). 

EG G Heimann Optoelectronics GmbH, Wiesbaden, Germany Radiation Image Detector RIS 256 - Datasheet... 

Improvements in technology will shape developments in PL in the near future. PL will be essential for demonstrating the achievement of new low-dimensional quantum microstructures. Data collection will become easier and ter with the continuing development of advanced focusing holographic gratir, array and imaging detectors, sensitive near infiared detectors, and tunable laser sources. 

Y Talmi, Multichannel Image Detectors, Vol 1 (1979), Vol II (1982), American Chemical Society, Washington DC, USA... 

All of the dissociation products from reactions (29), (32) and (34) were ionized by VUV laser and detected by ion image detector. They can be represented by the following reaction ... 

Chapter 8 written by Steve Vogel et al. also deals with sensitized emission based FRET methodology, but now using a spectral imaging detector device. Because a spectral detector and spectral unmixing software nowadays are standard options on the major commercial confocal microscopes, here a complete description is given how to quantify FRET from unmixed spectral components. 

Since TIRF produces an evanescent wave of typically 80 nm depth and several tens of microns width, detection of TIRF-induced fluorescence requires a camera-based (imaging) detector. Hence, implementing TIRF on scanning FLIM systems or multiphoton FLIM systems is generally not possible. To combine it with FLIM, a nanosecond-gated or high-frequency-modulated imaging detector is required in addition to a pulsed or modulated laser source. In this chapter, the implementation with of TIRF into a frequency-domain wide-field FLIM system is described. 

A much better time resolution, together with space resolution, can be obtained by new imaging detectors consisting of a microchannel plate photomultiplier (MCP) in which the disk anode is replaced by a coded anode (Kemnitz, 2001). Using a Ti-sapphire laser as excitation source and the single-photon timing method of detection, the time resolution is <10 ps. The space resolution is 100 pm (250 x 250 channels). 

Figure 18. Array of waveguide to free space couplers (a) in top view and (b) in a side view showing imaging detector array used for channel intensity acquisition.

There are two basic types of detectors used to measure ion signals, current detectors and ion counters. Each type has different implementations. A third type of detector is an imaging detector. In some SIMS instruments, the mass spectrometer is also an ion microscope, which transmits a stigmatic image of the sample to a detector plane. 

The Cameca ims 1280 is an ion microscope as well as an ion microprobe. That means that it can transmit direct ion images to an image detector. This capability has now been adapted for semi-quantitative and quantitative ion imaging. Direct ion imaging does not depend on the size of the primary ion beam for its spatial resolution. The new solid-state SCAPS detector has a spatial resolution of less than a micron, close to that of the NanoSIMS (see below). 

The imaging detectors, whether for point mapping, line scanning, or array detection, can be coupled with different types of spectrometers. Instrument types are classified by wavelength selection modality into imaging Fourier transform (FT) and tunable filter (TF) spectrometers, both of which are presented below, and dispersive spectrometers. FT imaging systems are classical laboratory instruments while TF spectrometers are compact and robust systems for chemical imaging. 

In the ion microscope the sample is illuminated with a broad ion beam (25 — 250 /rm). The secondary ions are filtered by mass spectrometers that conserve their spatial distribution. Ions are then visualized by microchannel plates as image detectors. The maximum lateral resolution of this method is in the order of 1 /tin. 

C. Grunzweig, G. Frei, E. Lehmann, G. Kuhne, C. David, Highly absorbing gadolinium test device to characterize the performance of neutron imaging detector systems. Rev. Sci. Instrum. 78, 053708 (2007)... 

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