Lenses designed to maintain focus over a wide temperature range

Standard, off-the-shelf lenses developed for imaging applications perform well in temperature-controlled environments or where temperatures vary only slightly. However, in certain security, defence, industrial and spaceborne applications, where imaging systems are prone to extreme or wide shifts in temperature, using athermalised lenses is key to minimising temperature-dependent performance changes.

Mark Pontin, Managing Director of Resolve Optics clarified “Because the different materials in a lens expand and contract at different rates, it is important that these factors are considered in the design phase to ensure a lens will remain in focus and provide good performance throughout its operating temperature range.”

He added: “Developing an athermalised lens design, is especially critical in the infrared (8 – 14 micron) waveband because the coefficient of thermal expansion of most infrared materials is orders of magnitude higher than those of visible glasses, creating large changes in the refractive index.”

Resolve Optics has experience of developing passively and mechanically athermalised lenses that offer stable imaging performance for applications with widely varying (-30°C to +60°C) or extreme temperatures (up to 950⁰C). Qualification of all athermalised lenses produced by Resolve Optics is conducted on state-of-the-art automated modulation transfer function (MTF) testing equipment. If required, athermalised lenses may be further qualified using the company’s inhouse vibration and shock testing facility.