Seeing Science: Confocal Microscopy from Biodesign Institute on Vimeo.

Scientists probe the mysteries of the natural world across an astonishing range of dimensions. They study particles that are smaller than atoms, such as quarks and leptons. They study walls or sheets of supercluster galaxies known as filaments—gargantuan structures measuring over a billion light years across.



Cells and other microscopic living things lie between these extremes. Microorganisms were discovered when early scientists developed microscopes.



One of the earliest pioneers of the microscopic realm was a 17th century Dutch tradesman named Antonie van Leeuwenhoek. Often tinkering in his free time at night, he made simple devices that would change the course of science. With little more than strong magnifying lenses mounted on silver or copper frames, van Leeuwenhoek brought into focus a previously unseen world.



In one experiment, van Leeuwenhoek sampled plaque from his own tooth. Upon examining the gooey substance with his microscope, he was astonished to find a lively zoo of living forms now rendered visible.

“The biggest sort. . . had a very strong and swift motion, and shot through the water (or spittle) like a pike does through the water. The second sort. . . oft-times spun round like a top. . . and these were far more in number," he wrote. These were the very first living bacteria ever seen. 



The microscope has become one of the most valuable tools ever created for exploring nature. Today, the field of microscopy continues to evolve, offering researchers a wide range of imaging technologies with a level of detail van Leeuwenhoek could only have dreamed of.



One of these techniques is the laser confocal scanning microscope, invented by Marvin Minsky in 1957. Laser confocal scanning microscopes, like the one at ASU’s Biodesign Institute, produce high-resolution images of biological materials.

Confocal microscopy is a form of fluorescence microscopy. The molecules of the material under study are put into an excited state using a high-intensity light. In response, the sample will emit light of longer wavelength—this is the fluorescence that will form the image.

A tiny pinhole in the detection pathway acts to reject of any out-of-focus light. This ensures that the final image reveals the specimen in vivid detail. This differs from conventional light microscopy in which images combine both in-focus and out-of-focus signals.



One of the critical features of confocal microscopy is that it can image successive layers through a specimen. These slices can be reassembled by computer into detailed 3-dimensional images. 

Imaging of living cells is also possible, providing they can be fixed in place during the imaging process.



Confocal microscopy is being used widely in biology and clinical medicine, thanks to the instrument’s ability to produce stunningly detailed images with very little sample preparation. Scientists study the inner states of normal cells and compare them with cells associated with diseases such as cancer, diabetes or Alzheimer’s. This helps them learn what goes wrong in cells as they become diseased.

Neuronal images in the slideshow above were supplied by Dr. Page Baluch at the School of Life Sciences, Keck Bioimaging Laboratory.