Thermal Imaging Lenses

Common Specifications Lens Substrate Black Diamond-6a AR Coating Range 8 - 12 µm Reflectance over Coating Range (Avg.)b <0.75% at 0° AOI AR Coating Reflectance
(Click Icon for Plot) Transmission
(Click Icon for Plot) Substrate Properties Refractive Index 2.7867 at 8 µmc Coefficient of
Thermal Expansion 22.5 x 10-6 / °C Thermooptic Coefficient (Δn / ΔT) 30.5 x 10-6 / °C Zemax Files Click on the red Document icon next to the item numbers below to access the Zemax file download. Our entire Zemax Catalog is also available. Webpage Features Clicking this info icon below will open a window that contains specifications, a reference drawing, and horizontal field of views for various detector sizes.

Features

• Focus Infrared Light without Introducing Spherical Aberration
• 8 - 12 µm AR Coating for Long-Wave Infrared (LWIR) Applications
• Black Diamond Substrate Provides Stable Operation up to 110 °C
• Horizontal Field of View (FOV) Options from 18° to 56°
• Focal Lengths of 4.0 to 24 mm Available
• Mounted in Threaded, Engraved Black Anodized Aluminum Housings
• Internally Sealed to IP67 Standard

Thorlabs offers Thermal Imaging Lenses that are ideal for focusing long-wave infrared (LWIR) sources onto detectors or image sensors. The lenses, manufactured by LightPath Technologies, are mounted in threaded, black anodized aluminum housings engraved with the focal length and f/# (see the table below for details). Designed using Black Diamond-6 glass, their aspheric geometry allows them to focus light without introducing spherical aberration. The TIL4 and TIL8 lenses feature singlet designs, while the TIL15, TIL20, and TIL24 are doublets.

Black Diamond
Black Diamond-6 (BD-6), a chalcogenide made of an amorphous mixture of arsenic (40%) and selenium (60%), has several advantages over germanium, which is traditionally used to fabricate IR optics. BD-6's thermally stable refractive index (see the Refractive Index tab) and low coefficient of thermal expansion (22.5 x 10-6 / °C) result in a smaller change in focal length as a function of temperature than for germanium. Additionally, germanium suffers from transmission loss as temperature increases, while BD-6 aspheric lenses can be used in environments up to 110 °C. This material performs particularly well over the 2 - 12 µm spectral range (click here for the transmission of an uncoated 1 mm thick sample).

Item # Info EFLa WDb HFOVc VFOVc Ideal Detector Formatd Surface Quality Aperture Height f/#e Design Thread TIL4 4.0 mm 5.33 mm 56° 42° 320 x 240 / 12 µm 80-60 Scratch-Dig Ø3.33 mm 6.50 mm 1.2 Singlet M10 x 0.5 - 6g TIL8 7.7 mm 10.06 mm 41° 31° 320 x 240 / 17 µm 100-60 Scratch-Dig Ø5.80 mm 11.50 mm 1.3 Singlet M19 x 0.5 - 6g TIL15 15 mm 10.07 mm 25° 18° 640 x 480 / 10 µm 80-50 Scratch-Dig Ø12.46 mm 17.00 mm 1.2 Doublet M19 x 0.5 - 6g TIL20 20 mm 7.96 mm 18° 14° 640 x 480 / 10 µm 80-50 Scratch-Dig Ø16.60 mm 21.42 mm 1.2 Doublet M19 x 0.5 - 6g TIL24 24 mm 10.00 mm 26° 19° 640 x 480 / 17 µm 100-60 Scratch-Dig Ø19.90 mm 26.50 mm 1.2 Doublet M25 x 0.5 - 6g