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2 Photon Random Access Mesoscope

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Imaging Instrumentation
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2 Photon Random Access Mesoscope

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About the innovation

Researchers at HHMI Janelia Research Campus have designed and built a 2-photon random access mesoscope (2P-RAM) that provides rapid imaging anywhere within a large tissue volume.

Cellular imaging can link activity in populations of neurons with behavior. But individual neurons are small, around 10μm in diameter. Most microscopes with subcellular resolution have small fields of view and, therefore, cannot image neurons in multiple brain areas simultaneously. Most large-field-of-view microscopes do not resolve single cells, especially in the axial dimension.

The patent-pending 2P-RAM addresses these problems with technological advancements in remote focusing, correction of field curvature, and fast lateral and axial scanning. The complete 2p-RAM allows high-resolution imaging anywhere within a volume spanning multiple brain areas (∅ 5 mm x 1 mm cylinder), and resolution is near-diffraction-limited (lateral, 0.66 μm, axial 4.09 μm at the center; excitation wavelength = 970 nm; numerical aperture = 0.6) over a large range of excitation wavelengths. A fast three-dimensional scanning system allows efficient sampling of neural activity in arbitrary regions of interest across the entire imaging volume.

The 2P-RAM was made public, and training was offered to attendees at a Janelia 2P-RAM workshop in August 2016, where researchers learned to make and use the first 13 instruments outside of Janelia. The instrument is now available for purchase at Thorlabs, Inc. (see the link to the right). The plans are available via Research License for individual academic use (see License Request to right). 


  • Field of view (FOV) diameter: 5.0 mm

  • Imaging volume depth: 1mm

  • Excitation numerical aperture (NA): 0.6

  • Collection numerical aperture (NA): 1.0

  • Excitation wavelengths: 900 nm-1070 nm

Related Components:

Various custom components have been designed for use with the 2P-RAM, including head plates and a tilt stage. The original tilt stage is a motorized positioner intended for use with an air-suspended ball treadmill, which can be complex and expensive. An alternative is a rigid floor for the test subject with a single degree of freedom for adjustment. The design is compatible with the head plates also offered here. 

Patent Status:

Published U.S. Patents 10,295,811 and 10,901,194


For inquiries, please reference:

Janelia 2016-006

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2P-RAM brain area from Sofroniew et al. 2016
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Michael Perham
Director, Innovations & External Relations
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