There are high-speed infrared cameras that are capable of solving a wide variety of problems as they use infrared detectors with different array sizes and pixels. Applications that do not require high-resolution, fast infrared cameras with QVGA detectors provide excellent performance. The 320×256 pixel 30-micron array has a very wide dynamic range due to the relatively large use of pixels. Large with deep pits, low noise, and ultra-high sensitivity.
Infrared sensing arrays are available in a variety of formats such as QVGA, VGA, and SXGA as shown. VGA and SXGA arrays have denser pixel arrays resulting in higher resolutions QVGA is economical and shows excellent dynamic range due to large sensitive pixels
Recently, smaller pixel pitch technology has resulted in infrared cameras with a 15-micron detection array, producing some of the most impressive thermal images to date. For higher resolution applications, cameras with larger free reverse image search arrays and smaller pixel pitches deliver high contrast and high sensitivity images. In addition, with a smaller pixel pitch, optics can further reduce costs.
2 Characteristics of infrared lenses
Lenses designed for high-speed infrared cameras have a unique feature of their own. In short, the most relevant terms are focal length (viewing angle), F-number (aperture), and resolution.
Focal Length: Lenses are usually indicated by the focal length (e.g. 50mm). The field of view of the camera and the lens combination depends on the focal length of the lens and the total diameter of the detector image area. As the focal length increases (or the detector decreases), the viewing angle of the lens becomes narrower (narrow).
A handy online display calculator for high-speed far-infrared cameras is available online.
In addition to regular focal lengths, there are also near-infrared lenses that enable high magnification (1x, 2x, 4x) photography of small objects.
Infrared close-up lenses provide a magnified view of the heat dissipation of small objects such as electronic components.
F-number: Unlike high-speed visible light cameras, objective lenses for infrared cameras using cooled infrared detectors must be designed to be compatible with the internal optical design. From the dewar (the cool case in which the FPA infrared detector resides), because the dewar is designed to have a cool compartment (or opening) inside to prevent parasitic radiation from hitting the detector. Due to the inactivation of the cold, the radiation from the camera and the lens is blocked from infrared rays that can be farther than that of the object to be observed. As a result, the infrared energy captured by the detector is mainly due to the radiation from the object. The position and size of the infrared lens exit pupil (and the f-number) should be designed to match the position and diameter of the dewar’s cold stop (in fact, the f-number of the lens may be less than the available f-number Efficiency is always as long as it is designed for a well-positioned cool spot).
Lenses for cameras equipped with cooled infrared detectors must not only be specially designed for but only for specific FPA resolution and location. But also to support the location and diameter of the cooling plug that prevents the parasitic radiation from hitting the detector.
Resolution: The Lens Modulation Transfer (MTF) feature is a property that determines the ability of a lens to correct details of the subject. Images produced by the optical system are subject to some degree of degradation due to lens aberration and diffraction. MTF explains how the image sharpness varies with the spatial frequency of the image content. As expected, large objects have a relatively high contrast compared to smaller ones. Low spatial frequencies typically have an MTF close to 1 (or 100%). As the spatial frequency increases, the MTF eventually drops to zero, which is the upper limit of resolution for optical systems.
