Capacitance Sensors vs. Eddy Current Sensors Application Note
Capacitance Sensors vs. Eddy Current Sensors Application Note Capacitance sensors and Eddy current sensors are both used for non-contact measurements. Capacitive probes use electric fields to measure the distance from the sensor face to the surface of a target that is typically conductive and grounded. Eddy current probes use an alternating AC current to induce a magnetic field in a conductive target instead. In turn, the induced magnetic field produces a back magnetic field that is proportional to the gap between the probe face and the target. In a recent application note, MTI Instruments examines the differences between capacitance [...]
Storm Watch / Tornado Radar
Storm Watch / Tornado Radar Customer Case On average, the United States experiences 100,000 thunderstorms each year, causing about 1,000 tornadoes. The customer is trying to determine what meteorological conditions enable a large rotating thunderstorm (a "supercell") to drop a dangerous tornado-funnel. By determining what conditions must exist for the formation of an especially fierce tornado, researchers hope to develop accurate predictions of when and where such a tornado may touch down, giving the people time to evacuate. The customer wants to study tornadoes and other severe-storm features with an X-Band polarimetric Doppler radar. This mobile cloud-profiling radar is [...]
Atmospheric Remote Sensing
Atmospheric Remote Sensing Customer Case The customer requires a combination of hardware and software ("data system") to do live update sampling, processing, display, and archival of atmospheric measurements using an airborne Lidar system. This system, which continuously emits laser pulses, measures line-of-sight velocity and backscattered signals at a particular range from the aircraft. Real-time performance is necessary to observe the state of the atmosphere and to assess the performance of their instrument. Their requirement is similar to that of laser Doppler anemometry. The signal from the Lidar system will vary continuously with time and the signal waveform will be [...]
Nuclear Decay Experiment
Nuclear Decay Experiment Customer Case A customer wants to measure nuclear decay rates of various radioactive isotopes. With each nuclear decay, the isotope under study simultaneously emits a beta particle, which is a high-speed electron, and a gamma particle, which is a high-frequency photon of light. Beta particles are detected with an efficiency of over 90% by a proportional gas counter that surrounds the radioactive isotope. Surrounding only one quarter of the isotope, a sodium iodide scintillator crystal detects gamma particles with about 25% efficiency. When it impinges on the scintillator crystal, a gamma creates a flash of visible [...]
Foam Density Measurement: Capacitance Sensors vs. Nuclear Gauges
This application note from MTI Instruments compares two technologies for measuring foam density: capacitance sensors and nuclear gauges. It examines the basic operating principles of each technology and explains why capacitance measurement is recommended for in-line measurement during foam manufacturing. Capacitance Sensors Capacitive probes are non-contact devices that use electric fields to measure foam density. In combination with a thickness value, a density measurement may be calculated. These probes consist of a capacitance sensor inside of a protective housing and are part of a larger measurement system that includes amplifiers, cables, and software. With parallel plate capacitance, the capacitance probe [...]
Electron Spin Resonance (ESR) Experiment
Electron Spin Resonance (ESR) Experiment Customer Case A customer has an Electronic Spin Resonance (ESR) experiment. ESR is based on the fact that the magnetic moment of an electron precesses in an applied magnetic field, not unlike a child's top in a gravitational field, at a well-defined frequency called the Larmor frequency. Electromagnetic radiation at the Larmor frequency, when impinging on such an electron, will be preferentially absorbed. This principle is identical to that employed in Nuclear Magnetic Resonance (NMR), where the atomic nucleus precesses. In NMR, Larmor frequencies are of order 100 MHz. Because the electron is 2000 [...]
Nuclear Ion Testing
Nuclear Ion Testing Customer Case This customer is involved in nuclear ion testing. The pulse amplitudes of nuclear ions from a detector must be measured and sorted into a histogram, which will show the number of times a given amplitude was received. The customer wants a "multi-channel analyzer" capable of analyzing 4,000 to 8,000 "channels." In the customer's terminology, "channels" are actually histogram bins. The customer has pulses coming in at 20 - 30 ms minimum interval and needs to peak detect (calculate the maximum value of the pulse). Then, based on peak height, each is stored in a [...]
Capacitance Sensing vs. Strain Gauge Sensing Application Note
Capacitance Sensing vs. Strain Gauge Sensing Application Note Capacitance probes that are embedded in piezo flexure stages can provide significantly greater accuracy than strain gauges. Although some minor mounting modifications are required, capacitance probes with picoscale positioning provide higher linearity, greater long-term stability, and better direct measurement. Capacitance sensors cost more, however, and are limited by sensing distance. Therefore, strain gauge sensors remain a good choice for applications where cost is a consideration, sensing distances are larger, and high resolution or high accuracy are required. In a recent application note, MTI Instruments examines the differences between capacitance probes and [...]
Alpha Particle Counting
Alpha Particle Counting Customer Case A customer has to characterize a new design for a solid state alpha particle detector. The detector is essentially a silicon diode with a large area face. Because alpha particles, which are high-speed helium nuclei, are electrically charged, they interact strongly with matter and lose their energy quickly upon entering a solid. When an alpha particle decelerates within the depletion region of the diode, it creates electron-hole pairs. The carriers are collected by the diode's electrodes and create a measurable current pulse. The customer's experimental solid state detector has two implanted electrodes whose signals [...]
Laser Spectroscopy
Laser Spectroscopy Customer Case An academic researcher is studying the attenuation properties of different materials inside Laser cavities for applications in Laser Spectroscopy. The Laser pulses are generated by one Laser, and are then transmitted by mirrors into another cavity filled with gaseous material. In the second cavity, the light pulses are continuously reflected by opposite mirrors and their intensities are measured by a transducer which converts them into decaying pulses of 30 nanosecond width. The decay takes about 40 microseconds to settle. The researcher is required to capture the decaying pulses and save the captured data onto the [...]