Another, more basic approach is to re-address the requirement for a laser. Could the application use LEDs or filtered broadband light?
A more complete solution which may allow the use of a laser is to first image the scene on a rotating disk with a “rough” surface, and re-imaging that on the camera sensor. The rotating disk would ideally rotate fast enough to blur the pattern out in a 30 millisecond frame rate, but can also be beneficial rotating at slower speeds, the speckle would appear as frame to frame white noise. Unfortunately, if the apparatus is being used to purposely monitor an interference pattern, i.e., an interferometer, this method would likely destroy that interference pattern too.
