The smaller the diameter of an endoscope, the greater its potential for minimally invasive surgical treatments. In conventional, flexible (fiber-based) endoscopes with small diameters (<200 µm), imaging is severely limited by the number of fiber cores. Due to this limitation, the image is pixelated. In this work, an engineering approach is used to increase the number of pixels by spectral multiplexing. However, this requires very small color-splitting optical systems at the distal end of the endoscope, i.e., at the body-facing end of the fiber. Such small dispersive optical systems are practically impossible to produce directly on the fiber using conventional techniques. Therefore, the idea is implemented using 3D-printed micro-optics. Preliminary work has shown that multiphoton lithography (fs DLW) is capable of producing imaging and color splitting systems on this size scale.
We present the optical design, fabrication and test of a fiber core multiplexing endoscope with a diameter of only 160 µm. Single-shot resolution enhancement is demonstrated by imaging of a USAF test chart and biological samples.
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