High-quality telecentric projection lens for vein visualization

Subject of study. A design of high-quality telecentric projection lenses that can be integrated into a miniprojector for projecting vein images onto human skin surfaces was investigated. Method. A numerical method based on Zemax software was used to design the lens. The required corrections were performed computationally to obtain a lens with components of similar diameter, significantly simplifying the mechanical structure, thus enabling easy and economical mass production. Main results. The new telecentric projection lens comprises seven spherical lenses, with a focal length and f-number of 20 mm and 2.51, respectively. The obtained value of the modulation transfer function (MTF) is extremely high: approximately 0.8 at 47 lines/mm and higher than 0.5 at 100 lines/mm. Relative distortion of the lens is less than 0.5 for the entire field of view. Owing to a unique technological feature, the fabricated projection lens demonstrated the measured MTF that was practically equal to the value calculated in the design. Practical significance. Using this projection lens in the vein finder enables the projection of sharp and precise images of veins onto the skin surface. Therefore, this device can help medical personnel in performing accurate and safe venipuncture. Owing to its low cost, compactness, and high quality of image formation, this projection lens is suitable for commercial purposes and for different applications of image formation. © 2022 Optica Publishing Group.