Array detectors imaging using

Figure 3.6 Schematicofa double-focusing sector field mass spectrograph with Mattauch-Herzog geometry with a linear imaging curve (double focusing for ions of all masses simultaneously) modified field combination with 70°. In the mass spectrograph, photographic ion detection or focal plane array detectors are used for quasi-simultaneous detection of separated ion beams. (H. Kienitz (ed.), Massen-spektrometrie (1968), Verlag Chemie, Weinheim. Reproduced by permission of Wiley-VCH)...

The detectors used for SIMS are electron multipliers (discussed in Section 14.2.1.1 and in Chapter 9) array detectors are used for imaging. 

To summarize, in this section we have shown how single-point microspectroscopy using the synchrotron IR source and small, confocal aperturing can deliver improved resolution and contrast for biological imaging when compared with various array detector microscopes using a thermal source, but these improvements come with a serious handicap - extremely long measurement times. 

The first step involved massive testing at ANDREX laboratory to determine the optimal detection process. Two imaging methods were discussed, one using a linear detector array, the other using a high resolution image intensifier. 

The main detectors used in AES today are photomultiplier tubes (PMTs), photodiode arrays (PDAs), charge-coupled devices (CCDs), and vidicons, image dissectors, and charge-injection detectors (CIDs). An innovative CCD detector for AES has been described [147]. New developments are the array detector AES. With modem multichannel echelle spectral analysers it is possible to analyse any luminous event (flash, spark, laser-induced plasma, discharge) instantly. Considering the complexity of emission spectra, the importance of spectral resolution cannot be overemphasised. Table 8.25 shows some typical spectral emission lines of some common elements. Atomic plasma emission sources can act as chromatographic detectors, e.g. GC-AED (see Chapter 4). 

Since the microarray spot images have many different sizes and shapes and some of the spots may not be located at the central position, addressing is essential to find the centre of the spots. In order to ensure accuracy of the measurements, an automatic spot detector is used to calculate the spacing between rows and columns of spots, the overall position of the array in the image and the spot size so that coordinates can be assigned to each of the spots in the array. 

TOF-MS to detect the electron current every nanosecond while the ions are arriving at the detector. The second setup can be used for imaging purposes, e.g., to construct an array detector (below). 

Detectors are used to convert X-ray flux into an electrical signal, which can then be digitized and stored. For imaging cabinet X-ray systems, the detectors usually consist of a folded linear array of scintillators optically coupled to photodiodes. Typically, 500-1000 such detector elements are present for single-energy imaging... 

The optical system comprises a laser, which is reflected by a mirror mounted on the back of the cantilever to another mirror that sends the reflected beam to an array detector. The position of the beam translates in the position of the cantilever in the vertical direction, whereas the lateral position in xy coordinates is inferred from the movement of the xy table. Essentially, AFM uses a feedback system to measure and regulate the force applied on the scanned sample, which allows the acquisition of images using very low forces. 

Analogous to the principal concept of multiplex CARS microspectroscopy (cf. Sect. 6.3.5), in multiplex SRS detection a pair of a broad-bandwidth pulse, eg., white-light femtosecond pulse, and a narrow-bandwidth picosecond pulse that determine the spectral width of the SRS spectrum and its inherent spectral resolution, respectively, is used to simultaneously excite multiple Raman resonances in the sample. Due to SRS, modulations appear in the spectrum of the transmitted broad-bandwidth pulse, which are read out using a photodiode array detector. Unlike SRS imaging, it is difficult to integrate phase-sensitive lock-in detection with a multiplex detector in order to directly retrieve the Raman spectrum from these modulations. Instead, two consecutive spectra, i.e., one with the narrow-bandwidth picosecond beam present and one with that beam blocked, are recorded. Their ratio allows the computation of the linear Raman spectrum that can readily be interpreted in a quantitative manner [49]. Unlike the spectral analysis of a multiplex CARS spectrum, no retrieval of hidden phase information is required to obtain the spontaneous Raman response in multiplex SRS microspectroscopy. 

Marcott, C., Reeder, R. C., Paschalis, E. P., Talakis, D. N., Boskey, A. L. and Mendelsohn, R. (1998) Infrared microspectroscopic imaging of biomineralized tissues using a mercury-cadmium-telluride focal-plane array detector. Cell. Mol. Biol. 44, 109-115. 

---