A scientific device and instrument company needed to develop an infrared lens with focal length of 40mm and f number of 0.98 for spectral imaging application. The spectral imager was meant to measure the relative concentrations of elements and compounds in fluid enabling precise monitoring firefighting applications. This required a precision lens with very little distortion.
Although the original design from this scientific device and instrument company offers high imaging quality and small distortion, it was not designed with an eye for manufacturing constraints. They originally used aspheric lens elements and a hazardous material (GaAs) to improve the modulation transfer function (MTF) and correct the chromatic aberration. Comparing with spherical lenses, the fabrication cost of aspherical lenses is higher. Using the toxic material GaAs can significantly increase the difficulty level for fabrication and incur unnecessary manufacturing cost.
Shanghai Optics was asked to come up with an alternate design that performed the same way the original lens did and more cost-effective to produce. We re-designed the infrared lens while taking into consideration both manufacturing cost and lens performance. There are no aspheric lens elements and hazard materials used in the redesigned lens system, and thus the manufacturing cost is significantly reduced. The lens performance also met our customer’s requirements for MTF, distortion, and image height offset at the working spectral range.
Our redesigned 40mm F/0.98 lens consists of 5 spherical lens elements and one filter. Figure 1 shows the final configuration of lens. The lens MTF is above 0.75 at 30lp/mm for the wavelength range of 3 ~ 5µm. Figure 2 shows the lens MTF plots. The lens distortion is less than 0.5%. Figure 3 shows the lens distortion plot.
Ultimately, Shanghai Optics DFM solution helped the customer reduce the lens cost about 30%, making it a practical inclusion in their spectral imaging equipment.
Contact us if we can help you with design for manufacturing (DFM) in your optical device or component. Custom optical design is our specialty, and our unique knowledge of manufacturing enables us to optimize your design for both performance and cost.