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Raman Spectroscopy of Surfaces
Published in Arthur T. Hubbard, The Handbook of Surface Imaging and Visualization, 2022
The quantum efficiency of two types of CCD detectors, a normal frontside-illuminated CCD detector, the Photometries PM512, and a thinned, back-illuminated CCD detector (Tektronix TK512-T), are plotted along with the quantum efficiency for the RCA C3104A PMT commonly employed for Raman spectroscopy, in Figure 47.4. As can be seen from this figure, the quantum efficiency of the CCDs greatly exceeds that of the photomultiplier tube. In particular, the quantum efficiency of the thinned, back-illuminated CCD is particularly high with a peak quantum efficiency of greater than 80%. Thus, these detectors represent the most ideal light detectors for visible wavelength radiation that are available. Their high quantum efficiency coupled with their low noise make them the detectors of choice for these extremely demanding surface Raman spectroscopic applications.
Optics Components and Electronic Equipment
Published in Vadim Backman, Adam Wax, Hao F. Zhang, A Laboratory Manual in Biophotonics, 2018
Vadim Backman, Adam Wax, Hao F. Zhang
A charge-coupled device (CCD) is a light-sensitive integrated circuit that stores and displays data belonging to an image where each pixel corresponds to an electric charge the intensity of which is proportional to a particular color. Implementation of CCDs is commonplace in cameras used for image acquisition (Figure 2.32). When an image is projected onto the lens of a CCD camera, a capacitor array (or photoactive region) inside the CCD accumulates electric charge where each individual capacitor's charge is proportional to the light intensity at a corresponding location. Following charge accumulation, a control circuit prompts each capacitor to transfer its charge to its neighbor until the last capacitor in the array deposits its charge into a charge amplifier. The charge amplifier converts the charge into a voltage, and this process is repeated until the image information is encoded as a sequence of voltages. These voltages can then be sampled, digitized, and stored for data acquisition purposes or output to a display.
Design and Fabrication of Optical and Fiber-Optic Humidity Sensors
Published in Ghenadii Korotcenkov, Handbook of Humidity Measurement, 2018
On account of the manufacturing distinctions, there have been some noticeable differences between CCD and CMOS sensors: CCD sensors create high-quality, low-noise images. CMOS sensors, traditionally, are more susceptible to noise.As each pixel on a CMOS sensor has several transistors located next to it, the light sensitivity of a CMOS chip tends to be lower. Many of the photons hitting the chip hit the transistors instead of the PD.CCDs use a process that consumes a lot of power. CCDs consume as much as 100 times more power than an equivalent CMOS sensor. This means that CMOS sensors should be considered as low-power devices, which have great battery life.CMOS chips can be fabricated on just about any standard silicon production line, so they tend to be extremely inexpensive compared to CCD sensors.CCD sensors have been mass produced for a longer period of time, so they are more mature. They tend to have higher quality and more pixels.
Assessing rechargeable batteries with 3D X-ray microscopy, computed tomography, and nanotomography
Published in Nondestructive Testing and Evaluation, 2022
Herminso Villarraga-Gómez, Dana L. Begun, Pradeep Bhattad, Kai Mo, Mansoureh Norouzi Rad, Robin T. White, Stephen T. Kelly
There are two common approaches to further increase the image resolution capabilities of flat-panel CT instruments: a reduction in the X-ray focal spot and/or the use of a higher resolution flat panel detector. However, this would not remove the geometric magnification limitations imposed by larger samples (>25 mm diameter). An alternative would be to incorporate optical lenses after X-ray detection to create a scintillator-lens-CCD1 detector coupling that optically magnifies the image (Figure 3). The scintillator-lens-CCD coupling is used for the indirect conversion of X-ray photons into electrically charged signals. The X-rays hit a scintillator, which converts the X-ray photons into visible light. The visible light then passes through an optical lens that projects a magnified image onto the CCD (charge-coupled device). This strategy enables effective detector pixel sizes down to 150 nm, producing XRM images with spatial resolutions of less than 700 nm [11].
Research on key technologies of UAV cluster cooperative system for Internet of Things applications
Published in Journal of Control and Decision, 2022
Formulas (14)∼(18) are all uniform (isotropic) sensor models. If an anisotropic sensor model is considered, and the definitions of the field of view and are similar, both models will be affected by the rotation angle of the sensor, which will be discussed later. Considering that the sensor performance function is affected by the maximum sensing range r, the following model can be selected: For vision-based sensor models, the field of view of a charge-coupled device image sensor (CCD) is generally rectangular, so it can also be analysed in a similar way. The system parameters of different sensors may be different. For example, the sensing range and field of view range of the sensors are different. Therefore, UAV clusters can be heterogeneous groups, and the design process is similar.
CMOS Implementation of Time Delay Integration (TDI) for Imaging Applications: A Brief Review
Published in IETE Technical Review, 2020
Sushil Kumar Semwal, Raghvendra Sahai Saxena
In this review, a timeline for development in CMOS-based TDI circuit architecture is presented. It has been observed that at initial stage more focus was on to implementation of more and more features so that the utility of TDI in CMOS may be proved. The optimization of circuit for better noise, power, etc. was handled in later development work. In fact, people at later stage had also developed the CCD process in CMOS technology itself to get the optimum advantage of both. With the development of TDI in CMOS imaging systems (CIS), CIS has attracted applications in widespread fields, e.g. scientific, medical, industrial, agriculture, etc. Imaging systems based on hybrid TDI sensor technology utilizes CCD-based TDI pixel array for light sensitivity and CMOS structure for readout electronics. In these systems CCD pixel structure delivers low noise and high dynamic range while CMOS technology enables low power with faster readouts. Such commercially available systems are offering linear arrays of up-to 16 k pixels, line rate of up-to 300 kHz, very low noise (∼10e-) and other loads of features [51–52].