Singlet gradient index lens for deep in vivo multiphoton microscopy

Area of Science:

• Neuroscience
• Optical Engineering
• Microscopy

Background:

• Micro-optical probes like gradient index (GRIN) lenses enable in vivo multiphoton microscopy of deep brain structures.
• Existing GRIN lenses suffer from spherical aberrations and limited fields-of-view, hindering deep brain imaging.
• Compound GRIN lenses are complex and restrict imaging capabilities.

Purpose of the Study:

• To develop an improved GRIN lens system for enhanced deep brain imaging.
• To overcome limitations of spherical aberration and field-of-view in current GRIN lens technology.
• To provide a cost-effective and easily adoptable solution for neuroscience research.

Main Methods:

• Utilized 0.5-mm-diameter, 1.7-mm-long GRIN lens singlets with 0.6 numerical aperture.
• Combined GRIN lens singlets with a cover glass and a conventional microscope objective correction collar.
• Balanced spherical aberrations to optimize imaging performance.

Main Results:

• Achieved a lateral resolution of 618 nm and an axial resolution of 5.5 μm.
• Demonstrated significantly improved resolution compared to compound GRIN lenses (≈ 1 μm lateral, ≈ 15 μm axial).
• Obtained fields-of-view exceeding 150 μm, substantially larger than compound GRIN lenses.

Conclusions:

• GRIN lens singlets with a cover glass offer a superior alternative to compound GRIN lenses for deep brain imaging.
• The developed system provides high resolution and large field-of-view at reduced cost.
• This disposable and easily assembled GRIN lens system is suitable for widespread adoption in neuroscience.