Application Design of Infrared Optical Lenses in Different Bands

Infrared optics, or more commonly known as IR optics, are used to collect, focus, or collimate the spectrum in the near infrared (NIR), shortwave infrared (SWIR), midwave infrared (MWIR), or long wave infrared (LWIR). The wavelength range of infrared optics is between 700 – 16000nm. Wavelength Optoelectronics offers a wide range of high performance infrared optics for life science, security, machine vision, thermal imaging and industrial applications. Together with our in-house manufacturing department, we design, develop, prototype, manufacture and assemble IR systems using diamond turning with laser-assisted tools, automated CNC polishers, coating and inspection capabilities. SWIR Lenses SWIR lens bands share imaging advantages over visible light and other thermal bands. It is used in electronic board inspection, material/food sorting, solar cell inspection, quality inspection, military applications, industrial machine vision. SWIR lenses are also used in situations where other detectors or cameras are not sensitive enough to abort limited detail recognition. Short-wave infrared lenses, especially extended-band short-wave infrared lenses, need to consider the materials that can be used for wide-band transmission, machinability, visible light transmission, etc. Therefore, ZnSe, ZnS, CaF2, etc. have become common choices. In addition, there are some rare of glass. However, it should be noted that under normal circumstances, these glasses are not in stock and the frequency of consumption is not high. Therefore, before adopting, it is necessary to determine whether these materials can be delivered on time and have the possibility of continuous supply. MWIR Lenses MWIR achromatic lenses are available for designers and researchers working in the 3µm to 5µm spectral region. These lenses have near-diffraction-limited performance for FTIR (Fourier Transform Infrared) spectroscopy and mid-wave infrared thermal imaging, as well as tunable quantum cascade lasers. The medium wave infrared lens is usually used with the medium wave cooling type detector, and the diaphragm is placed in front of the lens, so the lens is relatively large, and the so-called cold beam effect (ghosting, reflection, also known as the cold screen effect) must be considered. Although the cooling lens and detector are bulky, the detection distance can reach a long distance, such as focal length of 150 mm and 300 mm, and the distance of 10 km to 30 km can be seen. LWIR Lenses LWIR lenses are usually uncooled and therefore less sensitive. It allows users to see through dust or smoke, which makes them especially valuable in certain environments and applications. The field of view of the lens is mainly determined by the focal length and detector size. The design of long-wave infrared lenses is dominated by commercialization, that is, both low price and good effect. Therefore, aspherical surfaces are more commonly used. In addition, with the advancement of commercial applications, such as vehicle night vision, gun sights, mobile phones and other applications, chalcogenide glass began to become the ng of such applications. Since it can be molded at low temperature, the price of chalcogenide glass lenses can be very low if the number of chalcogenide glass lenses is large. Under extremely cold and hot conditions, especially when the temperature difference is large, the curvature of the infrared lens, the thickness of the lens, the refractive index of the lens barrel and the lens material change, causing the lens to defocus. In order to ensure a clear image, the lens needs to be refocused. Motorized or manual focus adjustment is required. In order to eliminate the adverse effects of temperature changes, athermal design is required. Usually, designers will use different optical materials to stop optical compensation (temperature difference), or use mechanical materials and optical materials to change trends. In the opposite design, optomechanical compensation is discontinued.