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Updated: Jun 16, 2026
Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
Published on: May 30, 2014
Expanding two-photon intravital microscopy to the infrared by means of optical parametric oscillator
Josephine Herz1, Volker Siffrin, Anja E Hauser
1Cecilie Vogt Klinik, Charité-University Medicine Berlin, Berlin, Germany.
Insights
Optical parametric oscillator (OPO) microscopy enables deep-tissue imaging of immune cell interactions in organs like the brain. This advanced technique improves visualization of chronic inflammation and cellular communication for biomedical research.
Area of Science:
- Biomedical imaging
- Cellular biology
- Neuroscience
Background:
- Chronic inflammation involves complex immune cell interactions within organs.
- Visualizing these interactions in deep tissues requires advanced multi-color imaging capabilities.
- Current methods face limitations in penetration depth and fluorophore compatibility.
Purpose of the Study:
- To demonstrate the utility of optical parametric oscillator (OPO)-based two-photon laser scanning microscopy for dynamic intravital imaging.
- To showcase the application of this technique in challenging organs like the brain and immune system.
- To highlight its relevance for long-term studies of pathological mechanisms such as chronic neuroinflammation.
Main Methods:
- Utilized OPO-based two-photon laser scanning microscopy for deep-tissue imaging.
- Expanded excitation wavelength into the infrared spectrum.
- Employed fluorescent proteins (e.g., GFP- and RFP-derivatives) for multi-color visualization.
Main Results:
- Achieved simultaneous imaging of fluorophores with distinct spectra.
- Increased tissue penetration depth by up to 80% compared to standard methods.
- Reduced photobleaching and phototoxicity while maintaining high resolution.
Conclusions:
- OPO microscopy offers powerful capabilities for dynamic intravital imaging in deep tissues.
- This technology overcomes limitations of conventional laser systems, enabling better visualization of cellular communication.
- It significantly impacts the selection of protein fluorophores for intravital bioscience and biomedical applications.
Abstract:
Chronic inflammation in various organs, such as the brain, implies that different subpopulations of immune cells interact with the cells of the target organ. To monitor this cellular communication both morphologically and functionally, the ability to visualize more than two colors in deep tissue is indispensable. Here, we demonstrate the pronounced power of optical parametric oscillator (OPO)-based two-photon laser scanning microscopy for dynamic intravital imaging in hardly accessible organs of the central nervous and of the immune system, with particular relevance for long-term investigations of pathological mechanisms (e.g., chronic neuroinflammation) necessitating the use of fluorescent proteins. Expanding the wavelength excitation farther to the infrared overcomes the current limitations of standard Titanium:Sapphire laser excitation, leading to 1), simultaneous imaging of fluorophores with largely different excitation and emission spectra (e.g., GFP-derivatives and RFP-derivatives); and 2), higher penetration depths in tissue (up to 80%) at higher resolution and with reduced photobleaching and phototoxicity. This tool opens up new opportunities for deep-tissue imaging and will have a tremendous impact on the choice of protein fluorophores for intravital applications in bioscience and biomedicine, as we demonstrate in this work.
