Biomedical Image Awards

How the images were made

Light microscopy, where visible light passes through sliced tissues under the microscope, has been used for hundreds of years to visualise details unseen by the naked eye. Samples are often stained with specific dyes to pick out different aspects of the internal structures, and coloured filters can also enhance structures in the sample. Polarising filters and other methods for deflecting the light beams can be used to enhance the unique characteristics of the samples and create a range of exciting visual effects.

When the wavelength of light becomes too large for what you are trying to visualise, electrons can be used instead. Transmission electron microscopy reveals internal structures in very thin sections of material, at much higher magnifications than are possible using light. Scanning electron microscopy also uses electron beams but generates three-dimensional images of the surfaces of objects. The electron beam hits the sample surface, causing electrons to be emitted; these electrons are detected by the microscope and create the image. Electron microscope images are always generated in black and white but are often colour-enhanced afterwards to highlight various features of the sample.

Fluorescence microscopy is a form of light microscopy that uses special coloured filters to detect specific wavelengths of light emitted from fluorescent markers in the sample. Confocal microscopy is a more recent refinement of this technique, which only detects the fluorescence coming from a very specific layer of a cell or tissue, excluding all out-of-focus light. This creates a sharp optical slice of the sample. If required, the slices can be reassembled by computer to give a complete picture of the specimen.

Stress photonics imaging uses a poleidoscope, a camera that measures the changes in the diffracted light resulting from the stresses in the material being examined. Computer analysis then generates a colour-coded image to enable visualisation of the stress pattern. This technique is more usually used in engineering to measure the stresses on metal components. Highly reflective dots can be used in conjunction with the diffraction images to generate a large amount of numerical information relating to the timing and direction of stress-related movement.