A Novel Design Method of Uniformity Energy Distribution Lens for Miniscopes

Abstract

Objective: Calcium imaging is an essential tool for obtaining neuroactivities to understand the complex function of the brain. The one-photon miniscope, the most widely used endoscope in neuroscience, is employed to record neuronal calcium activities in vivo. However, the current half ball lens overlooks the energy distribution in the brain field, resulting in non-uniform fluorescence imaging and the omission of important signals, leading to misunderstanding in brain science. The main flaw in the existing lens is the lack of controlled energy distribution, where the center fluorescence is much stronger than the edge area, causing the fluorescence noisy background to overlap with numerous neuron signals. To address this issue, we propose a novel approach to simplify the optical path by setting a medial target. By combining the Ray Mapping Method and Energy Feedback Method, we design and optimize the lens based on the energy mapping mesh. Simulation results demonstrate a 2.1-fold enhancement in energy distribution uniformity in the brain field compared to the original half-ball lens, with edge neurons receiving 6.95 times more energy. This novel design is theoretically proved to be an innovative improvement of the one-photon miniscope method, being a potential breakthrough of this mainstream method lasting more than ten years.

Keywords

• Freeform lens
• calcium imaging
• one-photon