Label-free imaging

It is not always required to label a sample with fluorophores in order to visualize it. Several structures and components can be imaged using label-free imaging techniques.

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second harmonic generation microscopy

Second harmonic generation (SHG) occurs when high-intensity light hits non-centro-symmetric structures (e.g. microtubules, enamel, collagen, myosin, ...). The energy conserving scattering process that follows, "combines two photons into one with double the frequency (half the wavelength) of the original photons". Contrast is created because only the highly ordered non-centro-symmetric structures can cause SHG while most biological structures are not highly ordered and thus produce no SHG signal. Because the SHG signal is created through scattering and doesn't require an excited state, there is no bleaching and no time delay. Additionally, the process itself causes no photodamage or phototoxicity, although absorption of the highly intense laserbeam can still cause damage in the sample. SHG microscopy can be performed relatively straightforward on a confocal microscope equipped with non-linear optics such as the LSM510 and LSM880.

label-free imaging of pollutants

Pollutants present in samples can potentially produce a specific and detectable signal when irradiated with high intensity light. At the AOMC we can investigate the spectral fingerprint of the signal and attempt to reliably separate pollutant signal from other sample components.