In this episode Shahriar takes a close look at the Resolve Handheld Raman Analyzer for Chemical Identification from Agilent. This instrument resembles a real-life Tricorder with its ability to identify chemicals through various opaque containers.
This video explores every aspect of this instrument's design from principle of operation to the modern electronics required to realize its function. The video is organized as follows:
00:00 – Introductions & first through-barrier scan example
02:46 – Raman history, invention & Nobel prize
04:41 – Infrared absorption, Raman spectroscopy theory, challenges and importance of fluoresce
10:49 – Fluorescence example & measurement using Uranium glass & HeCd laser
15:21 – Other applications of fluorescence such as microscopy
16:48 – Nonlinear optical effect and frequency doubling crystals, measurement of green laser
20:13 – Other applications of nonlinear optics, autocorrelation instrument to measure femtosecond pulses
23:18 – Electron excitation of atoms to produce photon emissions using Helium & Neon gasses
24:23 – Components required to build a Raman spectrometer
25:15 – Monochromator & spectrometer architectures, limitations & design
29:07 – Agilent Raman Spectrometer overall architecture, Raman chemical fingerprints
31:10 – Spatially Offset Raman Spectroscopy (SORS) theory & application
32:43 – Agilent Raman Resolve use-cases, accessories and application scenarios
36:03 – Measurements & identification of spilled unknown powders & liquids
40:53 – Through-barrier plastics & glass measurement of mixed liquids & acids
42:52 – Agilent Resolve extensive library & material categories, Reach-back support
44:03 – Chemical identification examples using the Vial accessory
47:26 – Trace chemical concentration & sensitivity measurement
48:34 – Concluding remarks
In this experiment Shahriar modifies a SourceTronic DC resistance meter due to its incredibly loud built-in buzzer. The instrument can sink up to 1A through a DUT and therefore measure down to micro-ohm resolution. The instrument also has offset voltage compensation capability to eliminate thermoelectric effects from bimetal contacts to the DUT. A direct measurement of the DUT current shows how the instrument is able to do this task in the background while measuring low resistances.
In this episode Shahriar takes a look at a faulty SRS DS360 ultra-low distortion function generator. This instrument is capable of producing pure sinusoids with better than -110dB of THD!
Although the unit powers on, changing the frequency or output signal does not result in any internal relay switching and the instrument does not produce any output signal.
The block diagram of the instrument as well as the theory of operation is described before the teardown. The teardown also shows the two board design and the interface between the digital/analog boards. The fault is finally traced to a broken optoisolator IC between the two boards. Without this interface IC none of the configuration parameters from the digital board arrive to the analog subsection. The faulty part is replaced and the unit is restored. The difficult measurement of the THD is also presented using an SRS SR830 DSP lock-in amplifier.
In this episode Shahriar investigates the problem preventing a Fluke 789 PrceossMeter from powering on. The issue is fairly simple and is quickly identified.
The basic functionality of the instrument (DC/AC voltage, current, resistance measurements) are verified as well as the current delivery of the unit.
The Signal Path (TSP) is a science & electrical engineering video blog for industry professionals, researchers & students. TSP is a not-for-profit website dedicated to provide free education spanning a wide range of electrical engineering & science topics. Equipment reviews, tutorials and repair videos are posted regularly.
