Features

• Diffraction-Limited On-Axis Performance
• AR Coated for the 3 - 5 µm Range
• Designs Incorporate Si and Ge Substrates
• Mounted in Engraved SM1-Compatible Housings

These AR-coated, air-spaced achromatic doublet lenses provide excellent transmission in the 3 - 5 µm range (surface reflectance for each coating can be seen in the graph to the right). They incorporate two AR-coated lenses, one with a germanium substrate and another with a silicon substrate.

Each achromatic doublet on this page has three design wavelengths: 3 µm, 4 µm, and 5 µm. By optimizing the design for these three wavelengths, the focal shift across the 3 - 5 µm range will be minimized (see Focal Shift tab for details), providing excellent on-axis performance.

Thorlabs' MWIR achromatic doublets are pre-mounted in engraved SM1-compatible mounts, making it easy to incorporate these optics into your setup. Each engraving includes the part number, AR coating range, focal length, an arrow indicating the direction of light propagation to collimate a point source, and an infinity symbol denoting that this lens has an infinite conjugate ratio (i.e., if a diverging light source is placed one focal length away from the flat side of the lens, the light rays emerging from the curved side will be collimated).

Note: We do not recommend disassembly of these lenses, as this may affect performance.