| 摘要 |
Apparatus for determining the velocity and direction of a moving object, the apparatus comprising: a coherent light (L) source arranged to generate a n incident beam (B) of coherent light; an optical imaging system arranged to receive light reflected from a moving object passing through the incident b eam and to focus the reflected light into a magnified image of the moving im age; a first optical mask (M) through which the magnified image is projected , the mask having a first region of alternating opaque and non-opaque areas having a first spacing and second region of alternating opaque and non-opaqu e areas having a second spacing different from the first spacing; a first li ght detector (D) arranged to receive the light signal transmitted through th e optical mask, the light signal comprising a series of pulses, and to calcu late the velocity and direction of the moving object as a function of the pu lse frequency and the spacing of the opaque areas of the optical mask.</SDOA B>
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