Instant SIM (iSIM)

Instant SIM is a technique pioneered by York et al and developed commercially by Visitech International Ltd. The concept uses the Image Scanning Microscopy (ISM) approach described mathematically by Colin Sheppard in 1988. The technology creates a super-resolution image in analogue form using optics alone so that the image produced by the camera requires no reconstruction, although deconvolution improves the resolution further.

For iSIM at the LMCB, use GFP4.

Airyscan

Airyscan is another ISM technique developed by Carl Zeiss and implemented on the company's LSM confocal microscopes.

iSIM, Airyscan and other image scanning microscopy techniques approach the theoretical maximum resolution possible using confocal microscopy but do not break Abbe's diffraction limit, which limits the resolution of light microscopy to approximately half the wavelength of light. For Airyscan at the LMCB, use the LSM 900 inverted or LSM 900 upright.

Structured Illumination Microscopy (SIM)

In Structured Illumination Microscopy high frequency information that is out of the bandwidth of the diffraction-limited microscope optics is shifted into the bandwidth by convolution with a known frequency; normally a grid pattern projected using a diffraction grating or spatial light modulator. The grating pattern must be shifted laterally and rotated in order to sample high frequencies in all orientations, which means 15 to 25 images must be taken to make one super-resolution image.

Its ability to access higher frequencies means SIM breaks the diffraction limit and doubles the resolution of light microscopy. However, SIM is slower than either iSIM or Airyscan and it is not confocal, so is not ideal for thick specimens with lots of out of focus light. For SIM at the LMCB, use the Carl Zeiss Elyra PS.1.