{"id":3846,"date":"2024-04-23T15:23:35","date_gmt":"2024-04-23T19:23:35","guid":{"rendered":"https:\/\/www.1stvision.com\/machine-vision-solutions\/?p=3846"},"modified":"2024-04-23T15:26:40","modified_gmt":"2024-04-23T19:26:40","slug":"lwir-long-wave-infrared-imaging-problems-solved","status":"publish","type":"post","link":"https:\/\/www.1stvision.com\/machine-vision-solutions\/2024\/04\/lwir-long-wave-infrared-imaging-problems-solved.html","title":{"rendered":"LWIR – Long Wave Infrared Imaging – Problems Solved"},"content":{"rendered":"\n

What applications challenges can LWIR solve?<\/h2>\n\n\n\n

LWIR is the acronym, is it reminds us where on the electromagnetic spectrum<\/a> we’re focused – wavelengths around 8 – 14 micrometers (8,000 – 14,000 nm). More descriptive is the term “thermal imaging”, which tells us we’re sensing temperatures not with a contact thermometer – but using non-contact sensors detecting emitted or radiated heat.<\/p>\n\n\n

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Remember COVID? Pre-screening for fever. Courtesy Teledyne DALSA.<\/figcaption><\/figure>\n<\/div>\n\n\n

Security, medical, fire detection, and environmental monitoring are common applications. More on applications further below. But first…<\/p>\n\n\n\n

How does an LWIR camera work?<\/h2>\n\n\n\n

Most readers probably come to thermal imaging with some prior knowledge or experience in visible imaging. Forget all that! Well not all of it.<\/p>\n\n\n\n

For visible imaging using CMOS sensors<\/a>, photons enter pixel wells and generate a voltage. The array of adjacent pixels are read out as a digital representation of the scene passed through the lens and onto the sensor, according to the optics of the lens and the resolution of the sensor. Thermal camera sensors work differently!<\/p>\n\n\n\n

Thermal cameras use a sensor that’s a microbolometer<\/a>. The helpful part of the analogy to a CMOS sensor is there we still have an array of pixels, which determines the resolution of the camera, as a 2D digital representation of the scene’s thermal characteristics. <\/p>\n\n\n\n

But unlike a CMOS sensor whose pixels react to photons, a microbolometers upper pixel surface, the detector, is comprised of IR absorbing material, such as Vanadium oxide. The detector is heated by the IR exposure, and the intensity of exposure in turn changes the electrical resistance. The change in electrical resistance is measured and passed by an electrode to a silicon substrate and readout integrated circuit.<\/p>\n\n\n

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Vanadium oxide (VOx) pixel structure – Courtesy Teledyne DALSA<\/figcaption><\/figure>\n<\/div>\n\n\n

Just as with visible imaging, for machine vision it’s the digital representation of the scene that matters, as it’s algorithms “consuming” the image in order to take some action: danger vs. safe; good part vs. bad part; steer left, straight, or right – or brake; etc. Whether one generates a pseudo-image for human consumption may well be unnecessary – or at least secondary.<\/p>\n\n\n\n

Applications in LWIR<\/h2>\n\n\n\n

Applications include but are not limited to:<\/p>\n\n\n\n

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  • Security e.g. intrusion detection<\/li>\n\n\n\n
  • Health screening e.g. sensing who has a fever<\/li>\n\n\n\n
  • Fire detection – detect heat from early combustion before smoke is detectable<\/li>\n\n\n\n
  • Building heat loss – for energy management and insulation planning<\/li>\n\n\n\n
  • Equipment monitoring e.g. heat signature may reveal worn bearings or need for lubrication<\/li>\n\n\n\n
  • Food safety – monitor whether required cooking temperatures attained before serving<\/li>\n<\/ul>\n\n\n\n

    You get the idea – if the thing you care about generates a heat signature distinct from the other things around it, thermal imaging may be just the thing.<\/p>\n\n\n\n

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