Integrating Optics and Parametrically-Resonant Micro-Scanner Design for Large Working Distance Implantable Microscopy

Area of Science:

• Biomedical Engineering
• Optical Engineering
• Microelectromechanical Systems

Background:

• Developing miniature, implantable fluorescence microscopes is crucial for in vivo biological research.
• Achieving a large working distance (WD) and field-of-view (FOV) while maintaining sub-cellular resolution presents significant design challenges.

Purpose of the Study:

• To investigate the interdependent design of optical paths and microelectromechanical system (MEMS) scanning mirrors for miniature implantable fluorescence microscopes.
• To maximize scan rate for high-NA focusing with a specified WD and FOV, enabling efficient subsurface imaging.

Main Methods:

• Employed linearized and numerical ray analyses to decouple optical and mechanical design aspects.
• Combined dynamic rotational analysis with a novel failure voltage model for parametrically-resonant electrostatic MEMS scanning mirrors.
• Optimized mirror parameters for speed within optical constraints and selected a compatible optical path for a small objective diameter.

Main Results:

• Developed a prototype instrument capable of sub-cellular resolution imaging.
• Achieved a field-of-view (FOV) of approximately 500 x 500 μm² at a working distance (WD) of up to 300 μm.
• Validated the prototype's performance on imaging targets and excised mouse brain tissue.

Conclusions:

• The interdependent design approach successfully integrated optical and MEMS scanning mirror components.
• The developed miniature microscope offers significant potential for advanced in vivo imaging applications, particularly in neuroscience.