Abstract—Designing a projection lens system for endoscopic 3D structured light system is challenging due to the extreme requirements of large depth of focus and light efficiency. We are proposing a systematic approach for finding out an optimal design that provides large depth of focus using conventional spherical lenses. Our contributions are 1) geometrical study of projection of light cone for depth of focus 2) Computer-aided optical design tool. Our proposed system is designed for a miniature binary-coded 3D structured light system, which makes it possible to apply to endoscope. The designed prototype diameter is only 2.8mm and total length is 13.78mm. Resulting system achieves a 15mm depth of focus in throw distance from 5mm to 20mm, and most of the MTF at 24lp/mm are more than 50% as shown in experimental results.
Index Terms—projection system, depth of field, endoscope, structured light, lens design
Cite: Xujian Chang and Sukhan Lee, "Chip-on-the-Tip Projection Design with Large Depth of Focus for Structured Light 3D Endoscopic Imaging," Journal of Image and Graphics, Vol. 3, No. 2, pp. 138-143, December 2015. doi: 10.18178/joig.3.2.138-143
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