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Shack-Hartmann Image Motion Monitor (SHIMM)

The SHIMM is a vertical turbulence monitor capable of operating continuously 24hours a day even in strong turbulence conditions. The SHIMM can measure the atmospheric optical turbulence coherence length, time and angle, the Rytov variance and a low resolution vertical profile.

The SHIMM is built from COTS components and uses an 11″ OTA, providing a cheap and portable solution.

Example 36hour continuous sequence of turbulence parameters measured on La Palma, Spain. The gap at ~6am on the first morning was due to high winds >50km/h.
The SHIMM operating in central London, UK.