What techniques are available?

  1. Laser Scanning Confocal Microscopy
  2. Multiphoton Excitation Microscopy
  3. Electron Microscopy

Coming soon:  Second Harmonic Generation Imaging, Magnetic Resonance Imaging Center, Time Resolved Fluorescence

Laser Scanning Confocal Microscopy (LSCM)

LSCM is a technique using fluorescent dyes for selective high resolution imaging of biological samples.  The dye is excited with a continuous wave UV or visible laser.  The fluorescence or emitted light is collected using a photomultiplier tube.  

Confocal microscopy differs from traditional fluorescence microscopy, in that the emitted light is collected through a pin-hole.  This minimizes the noise due to fluorescence from out-of-plane focus, and increases spatial resolution.  

LSCM allows the sample to be selectively scanned along the x-y plane creating image slices.   By changing the depth of focus, slices at different axial depths may be observed.  Typical penetration depth for LSCM for biological specimens is 10 to 100 m.

Multiphoton Excitation Microscopy (MPE)

MPE uses a mode-locked ultrafast laser to excite fluorescent dyes.  The intensity of the short laser pulse enables the sample to absorb two or more photons instantaneously.   In this case, dyes that would normally be excited in the UV or visible wavelength range may now be excited in the IR range.

  • greater penetration depth into the sample (~100-400 m)
  • decreased photodamage

This technique provides high resolution fluorescent imaging of live samples.

More about Leica LSCM and MPE system

For a more detailed discussion of MPE please feel free to view or download the Coherent MPE tutorial and glossary.  This is a in-depth discussion of the benefits, applications and necessary equipment for MPE experiments, along with a useful glossary of terms.

Contact Coherent at 1-800-527-3786 or

Electron Microscopy

Electron Microscopy uses accelerated high-energy electrons and electromagnetic lenses for focusing the electron beam onto the surface of a metal-coated sample.  This allows much greater resolution than light microscopy. 

In scanning electron microscopy (SEM) the electron beam is scanned across the sample and secondary electrons are ejected from the surface of the sample.  These secondary electrons are collected to form a picture of the surface topography. 

Transmission electron microscopy (TEM) enables even higher resolution.  This is achieved in part by TEM's use of electrons rather than visible light as the resolving medium and electromagnetic condensers and lenses rather than glass. Under high vacuum electrons penetrate thin specimens focused onto fluorescent screen, creating a magnified image.

Typical resolution for SEM is on the order of 5 nm, while TEM can resolve objects that are ~0.1 nm apart.  This is much greater than the 200 nm resolution achievable with visible light. 

To learn more about electron microscopy, and how it compares to light microscopy, visit these websites:
Darthmouth University Electron Microscopy Education Page
Electron Microscope Yellow Pages