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LWIR Athermalized Lenses for Thermal Imaging Camera

  • Wide focal length range: 4.3mm to 100mm
  • Broad working temperature range: -40℃ to 60℃
  • Passive optical athermalization design
  • Compact structure and IP67 sealing
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Code Focal length Module F# Focusing Mechanism Unit Price Delivery Cart
301-001 4.3mm L4.3F1.0 1.0 Athermalized Enquire 5-6 weeks
301-002 7.1mm L7.1F1.0 1.0 Athermalized Enquire 5-6 weeks
301-003 8mm L8F1.0 1.0 Athermalized Enquire 5-6 weeks
301-004 9mm L9F1.05 1.05 Athermalized Enquire 5-6 weeks
301-005 10mm L10F1.0 1.0 Athermalized Enquire 5-6 weeks
301-006 12.3mm L12.3F1.0 1.0 Athermalized Enquire 5-6 weeks
301-007 12.8mm L12.8F1.0 1.0 Athermalized Enquire 5-6 weeks
301-008 13mm L13F1.0 1.0 Athermalized Enquire 5-6 weeks
301-009 13mm L13F1.0 1.0 Athermalized Enquire 5-6 weeks
301-010 13mm L13F1.1 1.1 Athermalized Enquire 5-6 weeks
301-011 15mm L15F1.0 1.0 Athermalized Enquire 5-6 weeks
301-012 17mm L17F1.0 1.0 Athermalized Enquire 5-6 weeks
301-013 19mm L19F0.9 0.9 Athermalized Enquire 5-6 weeks
301-014 19mm L19F1.0 1.0 Athermalized Enquire 5-6 weeks
301-015 19mm L19F1.0 1.0 Athermalized Enquire 5-6 weeks
301-016 19mm L19F1.2 1.2 Athermalized Enquire 5-6 weeks
301-017 20mm L20F1.0 1.0 Athermalized Enquire 5-6 weeks
301-018 25mm L25F1.0 1.0 Athermalized Enquire 5-6 weeks
301-019 27mm L27F1.0 1.0 Athermalized Enquire 5-6 weeks
301-020 32mm L32F1.0 1.0 Athermalized Enquire 5-6 weeks
301-021 35mm L35F0.85 0.85 Athermalized Enquire 5-6 weeks
301-022 35mm L35F1.0 1.0 Athermalized Enquire 5-6 weeks
301-023 35mm L35F1.2 1.2 Athermalized Enquire 5-6 weeks
301-024 38mm L38F1.0 1.0 Athermalized Enquire 5-6 weeks
301-025 40mm L40F1.0 1.0 Athermalized Enquire 5-6 weeks
301-026 40mm L40F1.6 1.6 Athermalized Enquire 5-6 weeks
301-027 50mm L50F1.2 1.2 Athermalized Enquire 5-6 weeks
301-028 50mm L50F1.2 1.2 Athermalized Enquire 5-6 weeks
301-029 60mm L60F1.25 1.25 Athermalized Enquire 5-6 weeks
301-030 75mm L75F1.0 1.0 Athermalized Enquire 5-6 weeks
301-031 75mm L75F1.2 1.2 Athermalized Enquire 5-6 weeks
301-032 75mm L75F1.4 1.4 Athermalized Enquire 5-6 weeks
301-033 95mm L95F1.5 1.5 Athermalized Enquire 5-6 weeks
301-034 100mm L100F1.2 1.2 Athermalized Enquire 5-6 weeks
301-035 100mm L100F1.4 1.4 Athermalized Enquire 5-6 weeks
301-036 100mm L100F1.5 1.5 Athermalized Enquire 5-6 weeks

Infrared optical materials exhibit substantial changes in refractive index along with changes in temperature, this trait consequently leads to unstable focusing lengths of Infrared (IR) thermal imaging cameras, which are undesirable. Athermalization technique is often utilized in the design of IR thermal imaging to eliminate the defocus over an extended temperature range. There are three main techniques: Passive Optical Athermalization, Passive Mechanical Athermalization, and Active Electromechanical Athermalization. Passive Optical Athermalization eliminates the effect of defocus using combined different lens materials with complementing CTEs (Coefficients of Thermal Expansion) to compensate for thermal focus shift, the designed structure is simplified and involves no spacial displacement of the lenses, suitable for compact and light-weight applications.

Hangzhou Shalom EO offers off-the-shelf and custom LWIR thermal camera lenses of passive optical athermalization design, with a focus range of 4.3mm to 100mm and a temperature range of -40℃ to +60℃. With passive optical athermalization treatment, the lenses are compact with the absence of adadditionalptics to offset the thermal defocus, and therefore are advantageous for weight-sensitive designs. 


Tutorial:

This is a basic and brief tutorial to help you understand some important glossaries when you are selecting Optical Lenses and Camera Lenses.


Sensor Size and Resolution: The Sensor Size is the Width (Horizontal Length) and Height (Vertical Length) of the sensor/detector, often measured in mm, inch, or pixels. For Thermal Imaging Camera Lenses, Shalom EO gives the width and the height of the compliant detectors in pixels. Resolution is a measure of the image qualities, often given in ppi, which is the number of pixels per inch. For Thermal Imaging Camera Lenses, the resolution is given in the form of pixel pitch measured in μm.


Depth of Field (DOF):  DOF is the distance between the nearest and the furthest objects which are in sharp focus in the image. Depth of Field could be calculated, providing the focal length, subject distance, and acceptable Circle of Confusion (CoC, a blurred spot resulting from the imperfect focus of point light sources, and the numerical value of acceptable CoC refer to the diameter of the blurred spot which is tolerable). and the f-number. Assume the focal length is f, subject distance is u, CoC equals c, and the f-number is n, then: DOF=2u^2nc/f^2


Focal Length:  Focal Length is the distance from the optical center to the point at which radiations parallel to the optical axis of the lenses converge (i.e. the focal point). There is also Effective Focal Length (EFL), which is the distance from the principal point and the focal point, and Back Focal Length (BFL), which is the distance from the vertex of the rear lens to the back focal point.


Field of View (FOV):  Field of View is the maximum angle within which an optical instrument is sensitive to electromagnetic radiation. It describes the visual scope of a camera and is determined by the focal length and the sensor size of the detector. In the specification forms, the FOV given is measured as angular values. Click Here to Learn More about FOV.


f-number:  f-number, sometimes known as the f stop of the focal ratio, is the ratio of the focal length to the diameter of the entrance pupil (the aperture). The f-number indicates the ratio of radiations entering the lens, the greater the f-number, the smaller the aperture, and hence the less are the radiations transferred. Also, lenses with a lower f-number appear crisper, since the blurring spot will become less perceptible on the image plane as the aperture contracts. The term “lens speed” also refers to the f-number of the lenses.


Transmission of Materials: It is important that the lens modules should be made from materials that have high transmission to your wavelength of interest. For instance, in the case of the MWIR thermal lenses, Germanium is a common material due to its wide optical transmission range from 2 to 12 microns. Thermal properties are another issue to consider, since the refractive index of optical materials varies as temperature varies, which leads to defocus of the lenses. Therefore for working conditions with fluctuated temperatures, athermalized lens modules are more appropriate. The weight of the material should also be evaluated for weight-sensitive applications.


Image Distortion: Image Distortion is defined as the deviation from a rectilinear perspective, the result is the bending over of straight lines into curved lines in the image. The greater the FOV, the more difficult it is to correct the spherical images into a rectilinear perspective. Fisheye Lenses tend to have a rather significant image distortion.


Modulation Transfer Function (MTF): Modulation Transfer Function is a comprehensive measurement to assess the ability of the optical lens to maintain contrast between line pairs of the real object at different spatial frequencies, where the distribution of light from the object is regarded as sinusoidal functions with specific frequencies. The greater the MTF value, the more capable is the camera of preserving the details from the real scene in the image.


Spherical Aberration and ComaSpherical aberrations result from variations in the optical paths of light beams when passing through an optical lens' spherical surface. Monochromatic light beams that are incident on optical lenses but are not parallel to the optical axis tend to focus at the front of the mathematical focal point of the optics, while paraxial light beams that are closer to the optical axis tend to focus at the back of the mathematical focal point of the optics. Spherical aberrations can occur with lenses that have one or more spherical sides, including plano-convex lenses and ball lenses. When a cone of light from a point light source forms a defocused, comet-shaped, elliptical patch on the focal plane, coma, also known as comatic aberration, is said to be present. When the vertex of the cone of lights—the point light source—is not on the optical axis, this phenomenon takes place. Click here to learn more about spherical aberration and coma.

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