Let There be Light Sheet

In August 2004, light sheet microscopy burst onto the scientific scene. With a landmark paper, Ernst H.K. Stelzer and colleagues introduced the Selective Plane Illumination Microscopy (SPIM) that promised imaging of large samples at high speed and with minimal photodamage. The basic principle of the technique was relatively simple. By uncoupling the illumination and detection axis of the microscope and using thin sheet of laser light for direct optical sectioning through the imaged samples, the Heidelberg researchers opened a world of new possibilities. They showed that with this arrangement, it is possible to easily image even relatively large biological specimens by scanning through them with light sheets from multiple angles. This imaging happens at high speed, because CCD cameras could be used to capture an entire optical section at once. Moreover, due to the perpendicular arrangement of the microscope axes, only what is imaged gets illuminated. This results in improved sample health and allows very long-term imaging. The proposed microscope looked not only powerful, it also seemed to be relatively straightforward to build. Not surprisingly, the paper sparked the imagination of many biologists who dreamt about imaging large embryos in their entirety and at cellular resolution as they undergo development. The simplicity of the SPIM microscope and its potential to non-invasively image dynamic biological processes poised light sheet microscopy for rapid growth over the next decade.