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What Is an IR Microscope?

Paul Reed
Paul Reed

An Infrared (IR) microscope is a viewing device that can show images in the infrared light spectrum. IR is the frequency of light that is below the red frequencies visible to the human eye, and is related to heat given off by natural and artificial objects. This technology can be used for viewing images not seen with visible light, including changes in human cell samples and heat generated from electronic circuits.

Optical lenses that focus light to the viewing eyepiece can have limitations when trying to view infrared images. Normal optical microscopes can use infrared filters that block wavelengths of light other than IR, but these instruments can cause image blurring, known as aberration. Since the late 20th century, digital IR microscope technology has been replacing optical lenses, and use electronic sensors to detect infrared light and display the image on a computer screen. Increasingly sensitive digital image processors have improved the viewing capability, or resolution, of infrared technology.

Woman with hand on her hip
Woman with hand on her hip

Solid-state electronics use very small circuits created from layers of silicon and metals that can conduct electricity. Testing electronic circuits can be difficult due to the low voltages used and the very small circuit sizes. An IR microscope can view the solid-state circuits and look for changes in temperature from components that may be working incorrectly, and which will give higher temperatures than normally operating components.

Human tissue samples are screened for cancer cells and other abnormal conditions using infrared systems. Cancer cells can often create more heat than nearby normal cell tissues, a characteristic that can be used for cancer screening. Samples are placed under the IR microscope, and the system can be programmed to search for and identify unusual temperature regions.

Some plastics and other materials will not allow visible light to pass through them, making inspections difficult for damage or product quality testing. Infrared light can often show defects or damage and can be useful as a secondary quality check. An IR light source can be used to light the sample, and an IR microscope can view the resulting reflected light and detect unusual cracks or other imperfections.

Fiber optic cables are very thin glass fibers bundled together and used for telephone and video transmissions over long distances. Light passes through the cables, and there is very little heat generated from the transmission signals, making normal failure inspections difficult. An IR microscope can be used to detect fine cracks or other defects in fiber optic cables, allowing technicians to inspect new cables prior to installation, or existing cables damaged in the field.

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