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6.7" x 6.7", FL 2.8", IR Fresnel Lens

Stock #43-798
Qty 1-10
Qty 11-49
Qty 50+
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Dimensions (inches):
6.7 x 6.7
Dimensions (mm):
170.18 x 170.18
Effective Diameter (inches):
Effective Focal Length EFL (mm):
Effective Focal Length EFL (inches):
Center Thickness CT (inches):
Groove Density (grooves/inch):
Poly IR
Coefficient of Thermal Expansion CTE (10-6/°C):
11 - 13
Flexural Modulus (psi):
(100-260) x 103
Index of Refraction nd:
Visible (Sodium D Line): 1.52
8-14µm: 1.53
15µm+: 1.48
Operating Temperature (°C):
Shore Hardness:
Fresnel Lens
Wavelength Range (μm):
8 - 14
Wavelength Range (nm):
8000 - 14,000
Young's Modulus (psi):
(60-180) x 103

Product Family Description

  • Excellent Collecting Optics for Infrared Detectors
  • Minimal Absorption Loss in the 8-14μm Region

IR Fresnel lenses are molded in a flexible, 0.015" (0.457mm) thick, milky white plastic. Advantages of this product are: least absorption loss in the 8-14μm region, extremely thin with consistent thickness across the lens, large apertures and minimal thermal expansion. The design of an infrared-transmitting Fresnel lens involves many complex considerations. The grooved side of a Fresnel lens should face the longer conjugate (away from the detector when used to collect radiation). If the smooth side needs to face the longer conjugate for some nonoptical reason, the maximum aperture of the lens should be f/1.0. In this case, total internal reflection keeps all radiation from the area of the lens past f/1.0 from reaching the image. Even when the grooves face the longer conjugate, the portion of the lens past f/1.0 contributes a diminished amount and there is no significant contribution past f/0.5.

Technical Information

Durability Specifications
Effect of Sunlight None to Slight
Effect of Ultraviolet UV Stabilized
Effect of Weak Acids Very Little
Effect of Strong Acids Attacked by Oxidizing Acids
Effect of Weak Alkalies Very Little
Effect of Strong Alkalies Very Little
Effect of Organic Solvents Little below 60°C (140°F)

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