Hamamatsu Photonics' New Technology Escalates Spatial Resolution of TPEF/2PEF to Study Brain Functions

Posted  by GoPhotonics

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A research team from Hamamatsu Photonics has succeeded in developing a technology that uses spatial light modulators (SLM) and optical control technology to enhance the resolution of two-photon excitation microscopes. This new microscopy technique is being put to practical use across a broad range of fields including neuroscience and biology. It allows for detailed measurements of deep regions in biological samples and highly accurate observations of changes in the state of organelles that make up cells. This makes it a promising tool for applications in research on brain functions, kidney disease, and other illnesses.

The results from this research were published in the leading scientific journal on neuroscience “Frontiers in Neuroscience”. Results were achieved by a joint research effort with a laboratory endowed for Biophotonics Innovation and from a course on Virology and Parasitology offered at the Hamamatsu University School of Medicine

Research background

In scientific fields such as neuroscience, biology, and medicine, it is necessary to observe deeper positions of thick biological samples such as brain tissues. Two-photon excitation fluorescence microscopy (TPEF/2PEF) utilizes near-infrared light which penetrates well into biological samples, reaching deeper positions compared to ordinary fluorescence microscopes using visible light. In deep regions of a sample, however, aberrations are likely to occur depending on the lens’ characteristics and the sample itself, causing a significant loss in resolution. To cope with this problem, two-photon excitation fluorescence microscopes equipped with an SLM are being designed for everyday use. They cancel out the aberrations by feeding a hologram pattern into the SLM.

It is the growing demand from universities and research institutes for higher resolution observation that prompted the team to work jointly with the Hamamatsu University School of Medicine. Together, they created this technology to improve the resolution of two-photon excitation fluorescence microscopy for practical applications. 

Overview of research results

In this research, the team carefully considered the number and shapes of hologram pattern rings based on their unique optical control technology and eventually succeeded in finding an optimal pattern that effectively improves the resolution. To further boost it, they also added an optical component that controls the light polarization. By feeding the optimal hologram pattern and adding one optical component in this way, the resolution can be enhanced by about 20% without having to make drastic changes in the microscope optics design.

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