THT Mesoscope for Widefield Fluorescence Imaging

When performing GCaMP imaging using a commercially available fluorescence stereo microscope,

• The image is dark.
• The s/n ratios are low.
• The field of view is small.

As a result, you cannot see the activity you want to see...

The main reason is that the light is lost on its way from the sample to the camera, due to built-in functions such as zoom and microscope eyepieces.

For bright, widefield fluorescence imaging, a mesoscope that has a very simple design and large light path is recommended.

This page shows 5 reasons why bright, widefield fluorescence imaging is possible and optimized using our "THT Mesoscope".

What is THT Mesoscope?

The THT Mesoscope is a tandem-lens fluorescence optical system developed for detecting low light fluorescence that is emitted from biological samples at low magnifications.

Approximately 250 "THT Mesoscopes" have been sold in the last 20 years. They have been used in many scientific papers with high-speed fluorescence imaging applications, such as voltage-sensitive dye imaging, GCaMP imaging, and GEVI imaging, etc.

1. Brighter than other fluorescent stereo microscopes

No eyepieces, no zoom function, simple structure without loss of light

Features of THT Mesoscope include its simple yet flexible design, large light path for maximum throughput, and large custom-made fluorescence filter sets.

Compared to other fluorescent stereo microscopes, it is about 30 times brighter when the total magnification is 1x, and about 10 times brighter when the total magnification is 2x.

Large-diameter objective lenses and large fluorescence filters are used to collect as much light as possible

This mesoscope uses two Leica lenses and custom-made large fluorescent filters in order to maximize the amount of emitted light and increase S/N ratios.

2. Imaging the entire tissue with a wide field of view: Low magnification range from 0.19x to 6.3x

Depending on the combination of lenses used, the total magnification range is about 0.19x to 6.3x.

3. No need to tilt the animal sample: the THT Mesoscope can be tilted and rotated

A stand that can rotate the optical axis 360 degrees left and right is also available.

By tilting the optical axis, it is possible to image the entire temporal lobe of the brain without tilting the animal sample.

4. Simultaneous measurement of 2-3 wavelengths of multiple fluorescent probes is also possible.

The main unit can be used as a beam splitter, or a beam splitter can be connected to the main unit.

Simultaneous measurements of different fluorescent probes are possible as well as optical stimulation experiments with the use of optogenetics.

5. Hemodynamic correction for GCaMP signals is also possible with dual wavelength excitation

LEX9 is a high powered and highly stable LED light system. Two LED units can be installed inside LEX9..

Light from two LED units is output from the same optical path/light guide via an internally installed dichroic mirror. There is no need to use a separate beam splitter and connect it to the microscope.

It is ideal as an excitation light source for GCaMP imaging using 405nm and 460nm, as well as other dual-wavelength imaging experiments.

LEX9 with 405nm LED

LEX9 with 460nm LED

Applications

• Voltage sensitive dye imaging
• Widefield calcium imaging for in vivo brain
• Imaging with FRET, GCaMP, GEVI
• Intrinsic optical signal imaging based on hemoglobin and flavoprotein autofluorescence
• Optogentics and imaging
• Ratiometric fluorescence imaging with multiple camera heads