Infrared visibility keeps growing

Price and performance improve the allure of IR imaging for machine vision.

May 1st, 2004

Price and performance improve the allure of IR imaging for machine vision.

"Calorific imaging" certainly does not have the power of alliteration that "IR imaging" carries, yet that might have been the term if Sir William Hershel's first name for the radiation had stuck. The English astronomer discovered the IR wavelength region in 1800, when he subjected glass thermometers to different colors of the spectrum. "Calorific rays" was what he called the energy that lay just beyond red light.

In the past 40 years, the IR spectrum has become the domain of military, aerospace, and security applications, as well as for environmental and production monitoring. It's now interesting to watch the opening of additional markets for manufacturers of IR cameras and sensors in applications that rely on machine vision and industrial automation.

The barriers to entry in these markets have been high. Until the arrival of uncooled IR cameras, a camera could cost upwards of $30,000 with just a 160 × 120–pixel focal-plane array. In addition, the need for optics made of expensive materials like germanium, silicon, or sapphire made for very costly replacements in the event of damage.

The combination of uncooled IR cameras and affordable sensors with 320 × 240 pixels has opened up many new applications. For example, the better resolution enabled by the new sensors means that small parts with fine geometries can be examined, including printed circuit boards and other electronic components.

Near-IR (NIR), also known as short-wavelength IR (SWIR), is drawing particular interest because it makes possible the use of glass rather than more-expensive optics. In a harsh manufacturing environment where the optics may be frequently damaged, the reduced price for windows is a big advantage. Near-IR imaging (the 750-nm to 3-µm range) may also permit decisions to be made by a machine-vision system on the basis of physical properties other than shape. With an IR imaging spectrometer, for example, you could sort plastic bottles on a recycling line based on the type of plastic used to make each bottle rather than the visible shape of the container.

Infrared cameras are being developed that interface with programmable logic controllers (PLCs) and send alarm signals based on temperature maximum, minimum, and change. In addition, some new IR cameras come with standard digital interfaces such as USB 2.0 and Ethernet. Software development kits are beginning to appear offering C++, Visual Basic, and National Instruments (Austin, TX) LabView drivers.

As a result, the pieces are all falling into place for a significant growth in IR machine vision automation, where low cost, connectivity, and some measure of standardization is necessary for success.

On with the show

Changes in the imaging and machine vision industry are reflected in May's Vision Show East (Boston, MA; May 4–6), organized by the Automated Imaging Association (AIA; Ann Arbor, MI; www.machinevisiononline.com). The show has been focused primarily on imaging-related components. Attendance is usually around 2500, with about 100 exhibitors.

Times are changing, however. The Vision Show East is now collocated with two other shows: NEPCON East/Electro and Assembly East. Many attendees at NEPCON are customers for exhibitors at the Vision Show East, and many exhibitors at the Vision Show East have exhibited at past Assembly shows. The joining of component and system makers is welcome and should help draw more system integrators and end-users to both events.

There is another aspect of this year's Vision Show East to applaud—the technical sessions and tutorials are more extensive than past years. These reflect not just information on, for example, selecting lighting and optics, but include system design, machine vision for robot guidance, and numerous application and integration examples.

Finally, the Boston show features a floor party on May 5, Cinco de Mayo, with music, food, and beverages, where attendees and exhibitors from all three collocated shows can really relax and network. This is an industry that will certainly benefit from more integration, whether of components, systems, or people.

CONARD HOLTON is editor in chief of Vision Systems Design; e-mail: cholton@pennwell.com.

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