Silicon photodiode linear array detector

The classical silicon photodiode linear array manufactured by Reticon was the first detector marketed successfully. Similar solid state linear array detectors based on charge coupled devices, or charge.injection devices may also be of interest. Typical of the families of detectors, the Reticon detectors are built in a number of elements/array sizes. Commercially available units have anywhere from 128 to 1024 elements/array. Each individual element in the array is 1 x 1 mil to 1 x 100 mil in area, and are spaced on approximately 1 mil centers. The spectrometer system discussed in this article was built using Reticon-type devices. 

The use of a linear detector array in the image plane of a polychromator in place of the fluorescence monochromator in Figure 12.1 enables the parallel data accumulation of complete fluorescence spectra. Silicon photodiode arrays, operated in a CCD mode(34) are the most widely used detector elements. The spectral response of the diodes enables fluorescence to be detected from the near-UV up to ca. 1100 nm with a peak response in the near-IR. Up to 8192 elements are now available commercially in a single linear array at low cost. However, the small length of each element (ca. 10 [im) presently limits sensitivity and hence cylindrical lens demagnification is often necessary. 

Diode array detector A silicon chip that accommodates numerous photodiodes provides the capability to collect data from entire spectral regions simultaneously. Usually contains 64 to 4096 photodiodes arranged linearly. 

Antcliff, R. R., Hillard, M. E., and Jarrett, O. "Intensified Silicon Photodiode Array Detector Linearity Application to Coherent Anti-Stokes Raman Spectroscopy." Applied Optics 14 (1984) 2369. 

Silicon charge coupled devices (CCDs), commonly used in solid-state video cameras and in research applications, are being applied to low light level spectroscopy applications. The main advantage of area array CCDs over linear photodiode detectors is the two-dimensional format, which provides simultaneous measurements of spatial and spectral data. 

Photodiode arrays are one-dimensional detectors which consist of a linear array of photodiodes, produced in MOS technology on a single silicon chip [27, 28]. Arrays with up to 1024 diodes of 25.4 pm length and 2.5 mm width are presently available, leading to an active length of up to 25 mm. 

Milano et al. [153, 154] and Cook [34] introduced an approach to derivative spectra by substituting electronic wavelength modulation for the mechanical systems used in derivative spectrometers. This effect is achieved by superimposing a low-amplitude, periodic wave form on the horizontal sweep signal. In this way spectra were generated. Warner et al. [155] applied a vidicon detector for fast detection of fluorescence spectra and obtained derivatives of the stored data by digital computation. Cook et al. [156] also made use of a silicon vidicon detector for multichannel operations in rapid UV-VIS spectrophotometers with the possibility of first-order differentiation. For the same purpose Milano et al. [93, 157] used a multichannel linear photodiode array for detection of spectra in polychromator optics and stored data manipulations (d ). Technical explanations of the principles of diode array and vidicon devices cem be found in [158-161]. 

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