Excitation beyond the monochromatic laser limit: Simultaneous 3-D confocal and multiphoton microscopy with a tapered fiber as white-light laser source.
Timo Betz,
Jörn Teipel,
Daniel Koch,
Wolfgang Härtig,
Jochen Guck,
Josef Käs,
Harald Giessen
Journal of Biomedical Optics
10
(5)
054009
(2001)
| Journal
Confocal and multiphoton microscopy are essential tools in modern life sciences. They allow fast and highly resolved imaging of a<br>steadily growing number of fluorescent markers, ranging from fluorescent proteins to quantum dots and other fluorophores, used for the localization of molecules and the quantitative detection of molecular<br>properties within living cells and organisms. Up to now, only one physical limitation seemed to be unavoidable. Both confocal and<br>multiphoton microscopy rely on lasers as excitation sources, and their monochromatic radiation allows only a limited number of simultaneously usable dyes, which depends on the specific number of laser lines available in the used microscope. We have overcome this limitation by successfully replacing all excitation lasers in a standard confocal microscope with pulsed white light ranging from 430 to 1300 nm generated in a tapered silica fiber. With this easily reproducible method, simultaneous confocal and multiphoton microscopy was demonstrated. By developing a coherent and intense laser source with spectral width comparable to a mercury lamp, we provide the flexibility to excite any desired fluorophore combination
The optical stretcher: A novel laser tool to micromanipulate cells
Jochen Guck,
R Ananthakrishnan,
H Mahmood,
TJ Moon,
CC Cunningham,
J Kas
When a dielectric object is placed between two opposed, nonfocused laser beams, the total force acting on the object is zero but the surface forces are additive, thus leading to a stretching of the object along the axis of the beams. Using this principle, we have constructed a device, called an optical stretcher, that can be used to measure the viscoelastic properties of dielectric materials, including biologic materials such as cells, with the sensitivity necessary to distinguish even between different individual cytoskeletal phenotypes. We have successfully used the optical stretcher to deform human erythrocytes and mouse fibroblasts. In the optical stretcher, no focusing is required, thus radiation damage is minimized and the surface forces are not limited by the light power. The magnitude of the deforming forces in the optical stretcher thus bridges the gap between optical tweezers and atomic force microscopy for the study of biologic materials.
Contact
Cell Physics Division Prof. Vahid Sandoghdar Acting Division Head
Max Planck Institute for the Science of Light Staudtstr. 2 91058 Erlangen, Germany
