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Assembly of Microscopic Three-Dimensional Structures and Their Applications in Three-Dimensional Photonic Crystals
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
In this approach, the final 3D photonic crystal structure was considered as an ensemble of simple components. Unit components were prepared in the form of air-bridge plates using conventional semiconductor processing techniques for easy removal from a wafer during micromanipulation, and assembled into the designed 3D structure using a micromanipulation system. Here, InP was selected as the material for a 3D photonic crystal. Indium gallium arsenide (InGaAs) was deposited on an InP wafer using the metalorganic chemical vapor deposition (MOCVD) method as a sacrificial layer; then an InP layer was formed on it [2]. Subsequently, titanium and nickel layers, as a mask for dry etching processing, were formed using an evaporator, and a resist layer for electron-beam lithography was spin-coated onto the top (Figure 24.3).
Introduction to optical imaging
Published in Ahmad Fadzil Mohamad Hani, Dileep Kumar, Optical Imaging for Biomedical and Clinical Applications, 2017
Dileep Kumar, Ahmad Fadzil Mohamad Hani
The most commonly available single-channel photon detectors are PIN diode, avalanche photo diode (APD) and photomultiplier tube (PMT) [15]. PIN diodes are made up of silicon or In GaAs (indium gallium arsenide). Silicon photodiode operates in the range of 200–1100 nm and has a peak response at 900 nm, whereas In GaAs operates in the range of 800–1700 nm and has a peak response at 1500 nm. Signal is linearly dependent on the input light and there is no requirement of any high voltage. Because of very low sensitivity and small photoactive area, PIN photodiodes are often used in monitoring the excitation of intensity in fluorescence spectroscopy. However, the APD has a higher sensitivity compared to PIN photodiode due to the avalanche multiplication that results in the first stage of gain. A suitable APD is selected based on the range of wavelengths, size of detection area and electrical bandwidth [15]. In applications like fluorescence microscopy with very low signal detection level, APDs are used because of its higher sensitivity and faster response time. The PMT is made up of electron collector (anode), photon electron converter (cathode) and electron multiplier. With higher bandwidth and gain, PMTs are capable of photon counting in very low or short pulses of light. PMTs are selected based on wavelength, beam size and intensity requirements. Most common photodetectors in PET scanners are PMTs, which are used for small animal imaging [21].
Specialist Applications and Multispectral Imaging
Published in Adrian Davies, Digital Ultraviolet and Infrared Photography, 2017
During the 1950s and 1960s a Dutch physicist, J.R.J., van Asperen de Boer, used IR-sensitive video tubes (Vidicon) to collect data from wavelengths up to 2200nm, a system referred to as IR Reflectography. The later development of InGaAs (Indium gallium arsenide) cameras enabled high-resolution examination of paintings, but they have generally been superseded by modern high-resolution converted DSLRs.
Towards a real-time release of blends and tablets using NIR and Raman spectroscopy at commercial scales
Published in Pharmaceutical Development and Technology, 2023
Aruna Khanolkar, Viraj Thorat, Bhaskar Patil, Gautam Samanta
The NIR spectrophotometer SentroPAT BU II (Sentronic GmbH, Germany) was used for spectra collection for offline samples (blend components and blend) and inline monitoring during the blending and lubrication process. SentroPAT BU II instrument is having two tunable laser sources with a spectral range of 1350–1550 nm and 1550–1800 nm respectively. The spectral acquisition was done in reflectance mode using Indium Gallium Arsenide (InGaAs) detector. A detailed description of the spectra collection is given in our previous publication (Khanolkar et al. 2022). The acquired spectra were having a wavelength range of 1350–1800 nm at 1 nm intervals. The spectrophotometer has wavelength accuracy of <1 nm and wavelength reproducibility of <0.1 nm. API and Excipients samples were filled in 10 mL tubular glass vials and offline spectra were taken in triplicate for each sample using a spectrophotometer. For inline spectra collection, the instrument was mounted on the blender lid during blending and the spectra were collected for each revolution of the blender with a trigger angle at 30° rising edge of the blender.
In vivo near-infrared fluorescent optical imaging for CNS drug discovery
Published in Expert Opinion on Drug Discovery, 2020
Maria J. Moreno, Binbing Ling, Danica B. Stanimirovic
In the past decade, the developments in NIR imaging have been focused mainly on the so-called ‘first biological window’ or NIR-I (650–950 nm). More recently, the technology has moved one step further in the spectrum scale to explore the ‘second biological window’ or NIR-II, also termed shortwave infrared (SWIR, 1000–1700 nm) where there is an unparalleled improvement in transparency of the biological sample and a significant gain in both depth penetration and image resolution [19]. However, imaging in the SWIR has been challenging due to the lack of sensitive detectors. The silicon-based detectors used in the NIR-I window produce low signals beyond 900 nm [20]. Other detectors based on germanium (Ge), indium antimonide (InSb), and mercury cadmium telluride (HgCdTe) despite higher sensitivity in the SWIR range, still exhibit low efficiency [21–23]. Recent development of indium gallium arsenide (InGaAs)-based diode array detectors has provided more sensitive detection of longer wavelengths enabling explorations in the SWIR spectral region [21,24] for both in vivo and ex vivo imaging. This, in combination with the recent development of biologically compatible SWIR emitters such as organic dyes [25], single-wall carbon nanotubes (SWCNTs) [26]; quantum dots (QDs) [27]; rare-earth-doped nanocomposites [28] and gold nanoparticles [29], have revolutionized the field of fluorescent imaging potentially expanding its applications to both preclinical and clinical imaging.
Understanding the impact of magnesium stearate variability on tableting performance using a multivariate modeling approach
Published in Pharmaceutical Development and Technology, 2020
Ting Wang, Ahmed Ibrahim, Stephen W. Hoag
The spectral properties of the MgSt samples were characterized in our previous study; a brief summary is given below and a detailed description is given by Wang et al. (2019). NIR Spectra were measured with a NIRS XDS Rapid Content Analyzer (Metrohm, Columbia, MD, USA) from 400 to 2500nm at a 0.5nm resolution. Each spectrum was the average of 32 scans in diffuse reflectance mode measured through the bottom of a clear glass vial (Shell vial, 4ml, Sun-Sri, Rockwood, TN, USA). Three samples from each lot were scanned and the samples were obtained from different locations (top, middle and bottom) in a sample container (1kg). The average spectra are used for each lot. Raman spectra were acquired using a portable FT-Raman analyzer (RamanID, Real-Time Analyzers, Inc., Middletown, CT, USA). The laser wavelength is 1064nm, with spectral coverage from 150–3500cm−1 and a resolution of 8cm−1. The spectra obtained were the result of average of 50 scans. The detector is the thermos-electrically cooled indium gallium arsenide (InGaAs) detector. Powder samples in glass vial were placed into a Light-tight compartment in horizontal position. The spectra used for analysis are an average of three sample spectra.