Agreed, using a laser to perform the same sort of task as a collision avoidance sonar is difficult and compromised by turbidity due to fishy feacal farts. But this happens with sonars, profilers, altimeters too.
It could be done, but far better, cheaper, easier to meet the applications where sonars are found to be lacking. These areas are typically where high resolution and precision are required.
General rule – if you can see it, you can measure it using a laser without problems.
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