Proceedings Article | 17 April 2020
KEYWORDS: Lens design, Modulation transfer functions, Distortion, Monochromatic aberrations, Zemax, Industrial metrology, Optical design, Spherical lenses, Machine vision, Inspection
This paper analyzes the characteristics of the dual telecentric optical system and designs a compact dual telecentric laser lens using zemax optical design software. The lens image space F number is 8, the half object field of view is 30mm, the object distance is 100mm, the working distance is 80mm or less, and 8 optical lenses are used. The lens uses multiple meniscus lenses to correct aberrations such as field curvature and distortion due to the compact lens set. The image quality of the lens was evaluated in this paper. At a spatial frequency of 100 lp / mm, the MTF values are all above 0.4. The RMS radius is about 2μm, the Airy disk diameter is 10μm, and the telecentricity is less than 0.1%. The optical imaging system is all designed with a spherical lens. Traditional telecentric lenses generally have a working distance of about 200 mm, and telecentricity is generally between 1 and 10. In some situations where the working environment is harsh, conventional telecentric lenses are not suitable for the detection of precision instruments, and even cannot be used. And the accuracy is not high. The design is suitable for places with a working distance of less than 100 mm, and the telecentricity is high, that is, less than 1%, so the measurement accuracy is high. Considering the processing difficulty of a lens group, the thickness of each lens is as uniform as possible, and within the range that can be processed, thereby reducing the processing difficulty of the lens, thereby reducing the production cost of the lens, and the utility is higher. This article has designed a compact dual telecentric lens that maximizes the accuracy of the lens, taking into account miniaturization and cost. Eventually the telecentricity using the zemax operand RANG was maintained at 0.1% for both 0.5 and 0.7 field of view. Moreover, the lenses used are spherical, easy to process with respect to the aspherical surface, low in cost, and highly practical.
