Second Harmonic Generation Microscopy (SHG)

Second Harmonic Generation Imaging (SHG) is a second order coherent process where two lower energy photons are up-converted to exactly twice the incident frequency of an excitation laser. It has uses in many Bio-imaging applications.
Energy level diagram for the SGH mechanism
Figure 1. Energy level diagram for the SGH imaging mechanism.

Second Harmonic Generation Bio-Imaging Examples

Mouse mammary gland, label free image of collagen (SHG) and adipocytes (THG)
Figure 2. Mouse mammary gland, label free image of collagen (SHG, magenta) and adipocytes (THG, yellow), imaged with InSight DS+™.
Courtesy of Dr. Marie Irondelle, Institut Curie/CNRS, Paris, France

Zebrafish embryo (6 hours post fertilization) using label free THG at 1140 nm; imaged with InSight® DS+™
Figure 3. Mouse blood vessel wall, SHG and multiphoton excited fluorescence imaging with HighQ-2™ fs laser.
Courtesy of Dr. Marc van Zandvoort, Maastrich University

Mouse kidney, with CARS (red), SHG (blue) and autofluorescence (green)
Figure 4. Multi-Modal images of mouse kidney featuring CARS (lipids, red) SHG (collagen, blue) and MPE (elastin autofluorescence, green); imaged with Mai Tai® HP plus Inspire™ OPO.
Courtesy of Dr. Eric Potma, UC Irvine, CA

Human meibomian gland, CARS imaging the lipid rich meibocytes and SHG visualizing the surrounding collagen.
Figure 5. Human meibomian gland, CARS imaging the lipid rich meibocytes and SHG visualizing the surrounding collagen; acquired with InSight® DS+™.
Courtesy of Dr. Eric Potma, UC Irvine