LED illumination for medical applications with adjustable colour spectrum

An adjustable colour spectrum illumination system suitable for a microscope or other medical optical imaging device, comprising: a light source 1 with an adjustable colour spectrum; optical elements 4-15; and a sensor 18. The light source may be: an adjustable LED; a group of adjustable LEDs; or a laser. The LEDs may be white and/or colour LEDs wherein the current of individual LEDs is adjustable thereby adjusting the colour spectrum. The optical elements may be: lenses 8, 15; filters 4; diffusor plates 6; prismatic structures; and apertures 12. The optical elements may comprise a first lens or lens group 8, a second lens or lens group 12 and an optical element arranged therebetween. The light spot on the sensor may have a defined geometry.