A laser doppler velocimeter (LDV) has been designed and constructed for use in measuring ocean water flow velocity in the immediate vicinity of marine organisms anchored inside a water tunnel. The principal innovation reported here is the use of a microprocessor to produce an rsquo;rsquo;intelligentrsquo;rsquo; instrument which automatically calculates and displays the flow velocity. The resulting electronics design represents a considerable simplification over existing instruments which generally require the use of a separate autocorrelator and/or multihyphen;channel analyzer (MCA) plus an external minicomputer. The LDV configuration employed is a crossedhyphen;beam design using a 2hyphen;mW Hendash;Ne laser and inexpensive optics. A 48hyphen;channel 1hyphen;bit clipped autocorrelation function is implemented using a modified TTL design reported previously by Chen and cohyphen;workers. A Motorola 6800 micromodule updates the contents of each channel by direct memory access and displays the resulting correlogram on a CRT monitor. The velocity is periodically calculated (plusmn;5percnt;) and displayed by LED digits.
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