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How to Select IR Imagers.

Infared (IR) Energy: Part of a complete range of radiation called the electromagnetic spectrum. IR radiation lies between the visible and microwave portions of the electromagnetic spectrum. IR waves have wavelengths longer than visible and shorter than microwaves.

IR cameras have been used to measure temperature, monitor thermal performance, and identify heat-related problems for more than 30 years. Recent innovations in thermal imaging, particularly detector technology and software development, deliver powerful and cost-effective thermal analysis solutions to R&D professionals. Today, IR--or thermographic--cameras are smaller, more accurate, and more versatile than ever before.

The primary source of IR radiation is heat or thermal radiation. Any object that has a temperature radiates in the infrared. Even objects that are very cold, such as an ice cube, emit infrared. When an object is not quite hot enough to radiate visible light, it will emit most of its energy in the infrared. For example, hot charcoal may not give off light but it does emit IR radiation, which we feel as heat. The warmer the object, the more IR radiation it emits.

The electromagnetic (EM) spectrum is a name for a variety of types of radiation categorized together as a group. Radiation is energy that travels and spreads out as it goes--visible light that comes from a lamp in your house or radio waves that come from a radio station are two types of electromagnetic radiation. Other examples of EM radiation are microwaves, IR and ultraviolet light, x-rays, and gamma-rays. Hotter, more energetic objects and events create higher energy radiation than cool objects. Only extremely hot objects and particles moving at very high velocities can create high-energy radiation like x-rays and gamma-rays.

Early in the 1990s, a new detector technology called focal plane array (FPA) expanded the applications for thermography. An FPA is an IR detector incorporating rows and columns of individual sensors arranged in a 2-D grid. Each IR detector stares at the target and creates its own pixel of information. Thermographic FPA cameras today typically use a 256 x 256 or 320 x 240 IR detector, which is equivalent to having more than 78,000 thermocouples operating simultaneously, but in a non-contact mode.

Among the most exciting thermal detector technologies to evolve recently is commercial uncooled technology, notably the microbolometer, and ferroelectric or pyroelectric detectors. The resistive microbolometer is the only uncooled thermal detector technology yielding high response that is direct current (DC) restored, and therefore does not require a mechanical chopper to modulate the detector response. This excellent linearity is better than most cooled detectors, and translates directly into low spatial noise over a very broad temperature range. Isolation from neighboring pixels ensures negligible pixel cross talk, resulting in high thermal sensitivity.

SynQor, Hudson, Mass., developed the PowerQor DC/DC converter, a high-efficiency, high-density modular power supply. Unlike traditional converters, the PowerQor does not use a heatsink or baseplate to dissipate heat. The efficiency is so high that the SynQor converters provide more usable output power without a heatsink than traditional converters with a heatsink assembly.

In early development work, thermal imaging helped SynQor find something that was hotter than expected. Owning a thermal imaging camera provided the high-resolution, instant noncontact temperature measurement, and remote temperature interface necessary for a complete board inspection. If SynQor engineers were just using thermocouples and attaching them where they thought it was going to be hot, they would not have caught something glowing on the other side of the board.

Engineers at SynQor also make extensive use of IR imaging early in the product design cycle. "In development work, it is very helpful to get immediate feedback on the amount of output power and the power being dissipated. At SynQor, we have found that the best way to locate the power loss in circuitry is by using an IR camera. With IR, you can see where the power loss is and address that part of the circuit immediately," says Josh Bretz, design engineer at SynQor.
WEB RESOURCES FOR IR CAMERAS:
www.flir.com
observe.iw.nasa.gov/nasa/education/reference/main.html
www.optics.arizona.edu


Fallon is industrial marketing manager at FLIR Systems Inc.
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Title Annotation:infrared imaging equipment
Comment:How to Select IR Imagers.(infrared imaging equipment)
Author:Fallon, Mary
Publication:R & D
Article Type:Brief Article
Geographic Code:1USA
Date:Jun 1, 2001
Words:691
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