Sensing Solutions Lead to Recognition

Boulder, CO - Phase IV Engineering, Inc. announces that it has been chosen by CSIA as one of the most innovative technology companies in Colorado and will showcase its cutting edge innovations during the Colorado Technology Association’s (CSIA) DEMOgala on October 8, 2009, at the Colorado Convention Center in Denver.

Phase IV Engineering developed a sophisticated Passive RFID Sensing ASIC (application specific integrated circuit) called the “SensIC” and, during the DEMOgala Showcase, will demonstrate its adapted use in a number of applications ranging from aerospace, agriculture and food processing. This tiny chip offers battery-less sensing and can wirelessly measure and communicate the ID, temperature, and the value of an external MEMS sensor, such as pressure, shock, strain gauge, humidity, and more.

The theme of this year’s DEMOgala is “The Crossroads of Technology, Innovation & Growth”. The DEMOgala day long event features over 100 speakers on 15 different panels discussing the newest trends in technology. Topics include everything from cloud computing, software development, crowdsourcing, mobile applications, web commerce, open source, social networking, APIs, transparency, and much more.

GLD3 Label Detection Sensor

WINSBURG, OH – Pepperl+Fuchs introduces GLD3 Series Label Detection Sensors. With a quick and easy one-step teach and fast 100 µs response, GLD3 photoelectric slot sensors are specifically designed to detect paper, foil and many types of translucent adhesive labels on a roll.

GLD3 through beam sensors feature a robust, one-piece IP66 housing and are available with NPN and PNP outputs, and 3mm sensing range. A remote teach option is available, as are a choice of cabled or connector options to satisfy varying application needs.

The GLD3 series’ slotted design makes them well suited for use in web break detection, double sheet detection, splice detection, edge guiding and end-of-roll detection applications.

Pepperl+Fuchs
www.pepperl-fuchs.com

Electro-optical Sensor System for Navy Helicopters

The Raytheon Co. Space and Airborne Systems segment in McKinney, Texas, is providing the U.S. Navy with a helicopter-based electro-optical sensor suite — with infrared capability, laser designator, illuminator laser, and visible light sensor — under terms of a $44.3 million order awarded late Friday.

Raytheon is providing 62 of its AN/AAS-52 Multi-Spectral Targeting System (MTS) airborne sensor suites for Navy UH-60R and UH-60S helicopters to enhance their forward-looking infrared (FLIR) sensor capabilities, Navy officials announced.

The Raytheon MTS is a multi-use electro-optical infrared (EO/IR), and laser detecting-ranging-tracking set for long-range surveillance, target acquisition, tracking, rangefinding, and laser designation for the Hellfire missile and for all tri-service and NATO laser-guided munitions.

The MTS is designed for growth options such as multiple wavelength sensors, TV cameras (near-IR and color), illuminators, eyesafe rangefinders, spot trackers and other avionics through add-in circuitry.

Raytheon will build the systems in McKinney, Texas, and should be finished filling the Navy’s order by November 2011. Awarding the order were officials of the Naval Surface Warfare Center in Crane Ind.

Ratheon Company

Cylinder Position Sensors from TURCK

Minneapolis, MN — TURCK has expanded its line of BIM-UNT cylinder position sensors with a new 2-wire DC version, along with a NAMUR option for intrinsically safe applications. The cylinder position sensor features a wear-free design and short circuit protection, making it a suitable alternative to electromagnetic switches in the automotive industry. To further the sensor’s applicability in this industry, TURCK has integrated a weld-resistant TPU cable.

TURCK-BIM-UNT-Cylinder-Position-Sensor.jpg Measuring only 28 mm in total length, the BIM-UNT is one of the most compact cylinder position sensors on the market. The active sensing faces are located directly at the end of the sensor, allowing it to safely detect the piston rod’s end position on compact, short-stroke cylinders. BIM-UNT uses magneto-resistive, board-level technology that improves sensor performance and enhances housing options. It comes with a quick-mount tab that helps seat the sensor in the cylinder’s groove—even before the screw is tightened—to facilitate single-handed mounting. The screw is positioned away from the cable-end to provide cable strain relief, while also ensuring the sensor remains in place if the cable is pulled. With a broad range of accessories, from precision mounting to wire-strain relief products, BIM-UNT sensors can be simply installed in all T-groove, dovetail, round and tie rod pneumatic cylinders.

Photoelectric Sensors From Rockwell Automation

Rockwell Automation has released two new ranges of light array photoelectric sensors – the Allen-Bradley 45DLA discrete light array sensors and 45MLA measuring light array sensors.

Both ranges utilise optical synchronisation, and boast one of the smallest profiles on the market, making them ideal for a wide variety of applications, claims Rockwell Automation.

According to the company’s component area manager, Irma Napolitano, light array sensors represent a growing area for the company.

“The 45DLA and 45MLA sensor families will extend the scope of the company’s capabilities and complement our existing solutions,” she said.

“Furthermore, they will reinforce to the end-user that Rockwell Automation is a ‘one-stop shop’ for sensing requirements.”

The 45DLA is a discrete on-off light array sensor with 30mm resolution and integrated controller. Comprising five models—with sensing heights varying from 118 to 734mm and a sensing range of up to 8m—these sensors are designed for applications where products of different sizes, positions or orientation need to be detected.

Universal Pulley Torque Sensor

Sensor Developments, Inc. addresses the needs to measure belt or chain torque on pulley systems with the use of Sensor Developments Inc universal pulley torque sensor.

Capable of accepting various pulley wheels and shaft diameters, this sensor features a highly accurate integrated sensing element, capable of resolving low torque levels while being exposed to high radial loads created by belt drive systems. Use it to replace a standard pulley system for equipment like engines, generators, fluid pumps, or other motor driven equipment and continuously monitor real time torque while in operation.

This sensor can be adapted to a wide range of belt drive systems and can be installed in a dynamometer test stand or on vehicle. Various torque capacities and pulley gears can be designed to meet your specific requirements.

Sensor Detects Lung Cancer?

Lung cancer is a brutal disease, often not caught until it’s too late for treatment to do much good. Now researchers are building an electronic nose that could help physicians detect the disease during its initial stages. Using gold nanoparticles, scientists at the Israel Institute of Technology in Haifa have created sensors with an unprecedented sensitivity for sniffing out compounds present in the breath of lung-cancer patients.

Other attempts to do this have yielded promising results (see Lung-Cancer Breathalyzer and Cancer Breathalyzer), but those devices require a higher concentration of the telltale biomarker chemicals than the Israeli device. The chemicals, called volatile organic compounds (VOCs), are metabolic products present in the vapors that we breathe out, but they occur in such small amounts that researchers have had to find ways to increase their concentrations before testing. Now, Hossam Haick and his colleagues have built sensors using an array of gold nanoparticles that can detect these VOCs in their natural concentrations and under the humid conditions characteristic of human breath. Their research was recently published online in the journal Nature Nanotechnology.

Other devices used for the same kinds of tests depend on expensive means of VOC detection, such as optical sensors, mass spectrometry, and acoustic sensors. These systems aren’t always portable, either. Gold-nanoparticle sensors, however, have the potential to be small and inexpensive–the only problem has been getting the VOCs to stick to the gold. “It was quite a lot of work to get them to stick,” says Haick, a 2008 TR35 winner. “We’re the first to do so, as far as I know.” Because of an impending patent, Haick declined to explain how he achieved the desired stickiness.

Trans-Tek AC-AC LVDT

Trans-Tek has created a unique category of Linear Displacement Transducer (LVDT), originally developed for a manufacturer of tools for the down-hole oil drilling industry. The products are the result of a collaborative, creative process that produced several iterations for increasingly deeper pressures and higher temperatures. Two models evolved, based on the company’s Series 230. However, Trans-Tek can add the same features to any stroke AC-AC LVDT. Other applications outside of the oil industry include R&D testing and nearly anywhere extreme environments exist.

To accommodate such high pressure, the transducer housing is perforated to equalize pressure inside and outside the LVDT. Since the holes in the housing expose the coils inside, the fluid must be electrically non-conductive and chemically benign. Of course, many hydraulic oils meet this requirement. The high temperature ratings are achieved by using special internal materials.

These LVDT’s are rated for pressures to 35,000 psi, in electrically non-conductive, chemically benign media, at continuous temperatures as high as 450°F. Non-linearity is ±0.25% and temperature coefficient of sensitivity is ±0.01% per degree/F. A high sensitivity output offers infinite resolution in a variety of strokes. Trans-Tek high-temp/high-pressure LVDT’s are available in a choice of 3/8” or ¾” OD body style with signal conditioners for DC-DC or 4-20 mA operation.

Trans-Tek
www.transtekinc.biz

Understanding Infrared Thermometry

John R. Gyorki
Editorial Director

Infrared (IR) thermometry appears to be rather straight forward: point, press the button, and read the temperature. However, measurement results will be quite disappointing without a thorough understanding of the instruments’ principle of operation and specifications.

Temperature measurement instruments can be divided into contact and noncontact types. Sensors used in contact-type instruments include thermocouples, resistance temperature detectors (RTDs), thermistors, and semiconductor temperature sensors. Since contact sensors measure their own temperature they require physical contact with the measured object to bring the sensor body to the object’s temperature.

In some applications this contact creates problems: The measured object or media may be located at a distance or in a hazardous environment with no easy access. Measurements of moving objects are also difficult. A small object’s temperature may be altered when a relatively large sensor touches it and acts as a heat sink.

Noncontact infrared (IR) thermometers, if used properly, offer convenient solutions for these and many other measurement applications. However, you should select the measuring instrument and measurement techniques to be compatible with the application.

How IR Thermometry works
Heat is transferred from one body to another through conduction, convection, or radiation. Radiation is a process where heat energy in a form of electromagnetic waves is emitted by a hot object and absorbed by a colder object. Most of this radiation is in the infrared (IR) region of the electromagnetic spectrum, but some also spreads into the visible light band. The IR wavelength band stretches from 0.7 to 1000 microns, however practical IR measurement systems use only certain wavelength bands between 0.7 and 14 microns because the radiation is the strongest in this range.

If an object is exposed to IR energy radiated by a heat source, such as an electric heater, light bulb, sun, or other source, the energy reaching the object is called incident energy.  Part of this energy is reflected off the object surface. Theoretically, the object’s coefficient of reflectivity can vary from 0 (no reflection) to 1.0 (100% reflection). Rough, matt surfaces have low reflectivity. Polished and glossy surfaces, especially metals, have high reflectivity.

Depending on the object material, thickness, and the radiation wavelength, part of the radiation can go through the object or be transmitted. The coefficient of transmission can vary from 0 (no energy transmitted through object) to 1.0 (100% energy transmitted through object). High transmittance examples include glass, quartz, plastic film, and various gasses. Materials opaque in the IR spectrum have close to zero transmission coefficients.

The remaining energy is absorbed by the object and raises its temperature. A hypothetical body that has no reflection or transmission and absorbs all incident energy across the entire spectrum has a coefficient of absorption equal to 1.0 and is called a blackbody. Real-life objects, referred to as gray bodies, have coefficients of absorption that fall between 0 and 1.0.

Incident energy, W_I, is defined as:

W_I = W_R + W_T + W_A

Where:
W_I =  incident energy received by the object, W
W_R = energy reflected off the object’s surface, W
W_T = energy transmitted by the object, W
W_A = energy absorbed by the object, W

As the object absorbs energy and heats, it also emits energy.  When an object is in a state of thermal equilibrium, the amount of energy it absorbs (W_A) equals the amount of energy it emits (W_E): W_A = W_E. When an object absorbs more energy and its temperature increases, the amount of radiation it emits also increases.

IR thermometry is based on the fact that any body (solid, liquid, or gaseous) that has a temperature above absolute zero (0^oK or -273^oC) emits radiant energy. This energy is proportional to the forth power of the body temperature, and the body’s ability to absorb and emit IR energy is called emissivity. Energy radiated by a body can be expressed as follows:

W = E σ T4 A

Where:

W = energy, W
E = emissivity
σ = Stefan-Boltzmann Constant = 5.6703 10^-8, W/m²K⁴
T = absolute temperature, ^oK
A = emitting area, m²

Emissivity can range from 0 to 1 for various bodies. A hypothetical blackbody emits and absorbs all energy and thus has an emissivity equal to 1. Real-life objects have an emissivity between 0 and 1.

When an IR thermometer measures an object’s temperature, consider the energy that actually enters the lens. That is, in addition to emitting energy related to its own temperature, the object may reflect energy coming from another source, or transmit energy passing through it from a source behind it. For accurate measurements, survey the surrounding area for possible sources of extraneous IR radiation and choose the thermometer position and aiming angle to minimize the effects of those sources.

IR Thermometers
Infrared temperature measurement instrument design varies from simple hand-held thermometers that can be purchased for less than a hundred dollars to complex special-purpose instruments that cost hundreds and even thousands of dollars. However, some building blocks are common for most designs.

A typical infrared thermometer consists of optical components, IR detector, electronics, and a display or interface output stage. Optical parts focus radiation energy onto the IR detector and filter out radiation outside the desired wavelength band.  These components include collecting optics, lenses, fiber optics, and spectral optical filters.

IR Detectors
The majority of IR detectors are either single-wavelength (also called single-color), or dual-wavelength (also called two-color) type. The single-wavelength detectors measure IR energy within a certain wavelength band, and the instrument calculates object temperature based on the detector output and the preset emissivity. Some thermometers have adjustable emissivity, and most simple units have fixed emissivity.

Dual-wavelength detectors measure energy at two different wavelength bands, and the instrument calculates temperature based on the ratio of the two readings. If emissivity or the energy changes by the same amount at both bands, the measurement accuracy is not affected. Emissivity or the amount of radiated energy may change due to object change or movement, lens contamination or misalignment, or view obstruction.  The dual-wavelength detector’s drawback is higher cost and lower accuracy under certain conditions.

Emissivity of many materials and surfaces remains relatively constant over the IR wavelength range, and measuring energy in any narrower band will be acceptable. Other materials have wavelength bands with higher and lower emissivity due to high reflectivity or transmission, and require narrow band detectors tuned to high emissivity wavelengths.

Another factor is the atmosphere. Its transmission coefficient vs. wavelength curve has many peaks and valleys, which swing from almost 1.0 to near zero and block the IR energy transmission. Most general-purpose IR thermometers use the largest high-transmission band between 7 and 14 microns to minimize atmospheric attenuation.

To measure temperature of objects with emissivity that varies greatly over the IR wavelength spectrum and objects obscured by glass, smoke, steam, or other barriers, engineers need to use narrow band IR detectors. For example, short-wavelength detectors handle variable emissivity objects, lens contamination, and measurements through glass windows. Long-wavelength detectors are more prone to errors due to emissivity changes, but have a wide temperature range.

Special applications, such as measuring the temperature of glass, crystal, flame, gas, and thin film require detectors with specific narrow bands.  For example, detectors with a narrow band centered on 5 microns give the best results when measuring glass temperature.  Metals and metallic foils usually require 1 micron detectors where they have the highest level of radiation.

Based on the principle of operation, IR detectors fall into one of two categories: thermal detectors and photo detectors (photodiodes). Thermal IR detectors absorb the incident energy, raise the sensing element temperature, and change the detector’s electrical properties: thermopiles generate thermoelectric voltage, bolometers change resistance, and pyroelectric devices change their polarization. In general, they are slower than photo detectors.

A thermopile is made by connecting several thermocouples in series and placing their hot junctions in contact with a black body that absorbs the incident IR energy and heats the hot junctions. The cold junctions are placed in the area of the detector with adequate heat sinking. These detectors have fast response, broad band, large dynamic range, and are frequently used in general-purpose, automotive, air conditioning, and human-body thermometers.

Bolometers use a slab of material that changes its resistance in response to a change of temperature. The circuit converts resistance change to a voltage change, which is further processed by the instrument. Bolometers are frequently used for measuring low-level IR energy, often as an attachment to a telescope.

Pyroelectric devices become electrically charged when their body temperature changes. To produce a usable signal, the incident IR energy has to “pulse”. The output peak-to-peak AC signal is proportional to the pulse energy. Since energy emitted by measured objects is usually steady, thermometers that use pyroelectric detectors have a mechanical or optical chopper in front of the sensor. These sensors are used in many home security systems.

Photo detectors are built on a silicon substrate with an IR sensitive area that releases free electrons when impacted by the photons. The flow of electrons produces electrical signals proportional to the incident energy. These detectors are often used as arrays in thermal imaging systems.

A detector needs protection from the environment, and the selected window material must allow the correct wavelength band to pass through with minimum attenuation. A zinc sulfide or germanium window is best for the long-wavelength detectors, glass is suitable for short-wavelength detectors, and quartz for the mid-wavelength spectrum. Some instruments use a fiber-optic light guide to direct the radiation to the detector.

Since all types of IR detectors produce signals in the microvolt range, a high-gain amplifier should follow the detector.  Detector output vs. temperature curves are not linear and fluctuate greatly with a change in ambient temperature. To remedy this a signal-conditioning circuit stabilizes the temperature and linearizes the signal. Many applications require an analog-to-digital converter (ADC) to convert the temperature reading to a digital format.

Hand-held and many other instrument types have a built-in display, while other devices connect to a computer, data acquisition system, or temperature control system via an RS232 or RS-485 cable.  Some instruments simulate a thermocouple output, others have a 0 – 20 mA or 4 – 20 mA current loop, or voltage output.

The key specifications and considerations for any IR thermometer application are field of view (FOV) and distance; spectral band; response time; accuracy and repeatability; emissivity of the object or media being measured; media between the object and IR thermometer, such as vacuum, air, steam, gas, glass, or other; object temperature range; mounted or hand-held application; and type of output signal or display.

The FOV characterizes the diameter of a circle (target) that the IR detector will “see” at a certain distance from the measured surface. However, there is always a minimum target diameter that depends on the optical system and detector size. The detector measures and averages temperatures of all objects within the target area.  FOV is commonly called distance-to-spot size ratio and is a ratio of the distance between the meter and the target to the diameter of the target.

For example, a 10:1 distance-to-spot size ratio means that if a measured surface is located 10 inches from the thermometer it will measure and average the temperature of a circle with 1 in.diameter. Move the thermometer away to 20 in. and the target will increase to 2 in., and so on. A thermometer with a 1:1 ratio will measure within a one-foot diameter circle when held one foot away from the target.

Thermometers designed for measurements of small areas have a very narrow FOV and measure temperatures of objects less than a tenth of an inch. For example, such a thermometer held near a component on a pc board will measure the temperature of just that component and ignore the
components around it.

Other optical systems allow accurate temperature measurement of a spot several inches in diameter at a distance of tens of feet. However, such measurements require accurate pointing. Though notches on top of the instrument provide some help, aiming lights and built-in laser pointers prove to be most helpful.

Unfortunately, a laser pointer may occasionally lead to erroneous measurements if the user is not familiar with the IR thermometer operation and the FOV concept. Some first-time users mistakenly think that the laser beam that they see has something to do with the process of measuring temperature.  They presume that the instrument displays the temperature of the tiny spot where the laser beam meets the surface. Such measurements will not yield satisfactory results.

Practical considerations

Here are some helpful tips:
• Avoid degrading measurement accuracy by environmental elements, such as dirt, dust, smoke, steam, other vapors, extremely high or low ambient temperatures, and electromagnetic interference from other devices.
• Select an IR thermometer with a wavelength band compatible with the measured object (especially high reflectivity objects) and with the media between the thermometer and measured object (especially glass, smoke, or steam).
• Select an instrument with a temperature range not much greater than the maximum application temperature. Wider than needed temperature ranges lead to lower accuracy or higher instrument cost.
• An IR thermometer averages the temperature of all objects within its field of view: Select the instrument with an appropriate FOV, and calculate the proper distance so that only the desired area is measured.
• Avoid hot objects near the measured object. They radiate energy that can be reflected or transmitted by the measured object into the thermometer FOV.

For more information go to:

www.omega.com

www.watlow.com

www.gesensing.com

www.raytek.com

www.murata.com

Iris Recognition Sensor Gets a Speed Boost

Smart Sensors Limited, a spin-out from the University of Bath, UK, has
introduced version 2 of its MIRLIN software toolkit, enabling security system
developers to create iris recognition systems capable of 2 million matches per
second, four times faster than other current technologies. Functions include
image acquisition, enrollment, and verification or determination of identity
(ID) from human irises.

Analyzing a digital image of the iris using techniques similar to those employed
in video encoding, the Smart Sensors patented solution requires less processing
power than alternative methods and the software code can operate in only around
300 Kilobytes of memory on a silicon chip. As a result, systems can be based on
small, low-cost microcontrollers with less processing power than an ordinary
personal computer. This makes the technology suitable for use in fixed or
battery-operated, handheld equipment.

Smart Sensors` MIRLIN software development kits (SDK) enable systems to be
optimized for the best combination of speed and accuracy. Images can be scanned
in segments from 18 degrees to 0.72 degrees wide, depending on the accuracy
required. The technology works with iris characteristics that generally conform
to ISO/IEC standards but it is capable of delivering accurate results with
images that are significantly poorer than those defined by the standard.

The SDK can work with a variety of image sources, including several
manufacturers` iris cameras. Versions are available to support various
processors and operating systems. To make licensing more attractive for
customers, the company only charges a fee for each product or each server on a
network, not for every user or enrollment. Customers are supported through
service level agreements that provide bug fixes and product enhancements.

Smart Sensors, which is based in the SETsquared business incubator at the
University of Bath, has recently been awarded the Frost & Sullivan “Global Iris
Biometric Systems Technology Innovation of the Year Award” for 2009.

Smart Sensors Limited

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