Spinning disk confocals

Spinning disk confocals are sort of half way between a wide-field fluorescence scope and a scanning confocal. The confocal principle is the same: a spot of light is scanned across the sample and a pinhole blocks the out of focus light. The main differences from a point-scanning confocal are:

  • In a spinning disk there are many spots of light
  • The spots are "moved" by means of a rotating disk with holes rather than scanning mirrors
  • The light is collected on a CCD camera rather than PMT
  • The entire image is collected at the same time (faster)

Again the excitation is produced by a laser. This is defocused onto the disks, the first disc consists of many collector lenses which focus the light onto the pinhole disk below. This disk rotates very rapidly so the many spots are scanned across the sample.

The emission light is descanned through the pinhole (the speed of the disk is insignificant compared to the speed of light) and just like a regular fluorescence scope it is separated from the excitation light by a dichroic and goes to a CCD camera.

Spinning disks are very good for living samples because they are fast and have relatively low phototoxicity. For fixed samples, you are probably better off with a point-scanning confocal.