The path from Helmholtz’s Augenspiegel to the modern scanning laser ophthalmoscope is filled with examples of optical technology transfers. The Scanning Laser Ophthalmoscope is an example of optical technology transfer, specifically laser technology to the scanning ophthalmoscope. In the scanning device the illumination is incident on a small spot of the fundus for a short time period, the illumination beam is displaced to the adjacent small spot, and this continues until the field of view of the fundus is covered. Simultaneously with the spot of illumination, the scattered light is detected; the accumulation of all of the light from all of the illuminated spots forms the image of the fundus as seen on the display of the scanning laser ophthalmoscope. If a confocal system is a component of the scanning laser ophthalmoscope there is excellent discrimination against stray light. The aperture in front of the detector is optically focused on the illumination spot of the fundus. The human eye is the limiting factor of the resolution of the SLO. The other important limiting factor is light diffraction which defines the limiting size of the laser beam spot of the focused laser beam on the retina. The invention of the scanning laser ophthalmoscope and its further development in the last two decades has advanced clinical ophthalmology.