An all solid-state approach to the precise frequency synthesis and control of widely tunable terahertz radiation by differencing continuous-wave diode lasers at 850 nm is reported in this paper. The difference frequency is synthesized by three fiber-coupled external-cavity laser diodes. Two of the lasers are Pound–Drever–Hall locked to different orders of a Fabry–Perot (FP) cavity, and the thir...

We present commissioning and comprehensive evaluation for ArcCHECK as a QA equipment for volumetric-modulated arc therapy (VMAT), using the 6 MV photon beam with and without the flattening filter, and the SNC patient software (version 6.2). In addition to commissioning involving absolute dose calibration, array calibration, and PMMA density verification, ArcCHECK was evaluated for its response ...

An on-site determination method for trace manganese has been developed using the manganese-catalyzed oxidation of Malachite Green (MG) with potassium periodate. Absorbance measurement of MG was carried out using a laboratory-made palm-top size colorimeter with a red-green-blue light-emitting diode. The reciprocal value (1/τ) of the reaction time at a fixed absorbance value for red light was cho...

The NASA Earth Science System Pathfinder (ESSP) mission Aquarius, will measure global ocean surface salinity with ~100 km spatial resolution every 7-days with an average monthly salinity accuracy of 0.2 psu (parts per thousand). This requires an L-band low-noise radiometer with the long-term calibration stability of ≤0.1 K over 7 days. A three-year research program on radiometer stability has a...

This paper presents the development of a capacitor ESR meter, which covers capacitance and measurements as well interrelationship constituent parts/circuits. The idea is to keep hardware design simple, transferring complexity firmware controls hardware. In particular, it uses automatic functions controlled by relays thus there no need for switches its calibration ensures menus. work voltmeter f...

This paper provides an Analog Behavioral Model (ABM) in PSpice of a tunnel diode The PSpice parameters are implemented as separate parameterized blocks constructed from SPICE (ABM) controlled sources and extracted through experiment. A tunnel diode based oscillator is also proposed and simulated using circuit analysis software. The behavior of the tunnel diode is simulated and compared to the m...

We present the use of a near-infrared ~IR! laser Raman spectroscopy instrument to measure the concentrations of many important analytes at their clinically relevant levels in the simulated human serum. The Raman signal is generated by a 745 nm diode laser in a disposable waveguide capillary cell that contains a submicroliter sample. The Raman spectrum is acquired from the sample in 10 s. The ma...

The combination of reflectance, fluorescence, and Raman spectroscopy-termed multimodal spectroscopy (MMS)-provides complementary and depth-sensitive information about tissue composition. As such, MMS is a promising tool for disease diagnosis, particularly in atherosclerosis and breast cancer. We have developed an integrated MMS instrument and optical fiber spectral probe for simultaneous collec...