1. A method implemented in a measuring instrument for detecting presence of at least one target said method comprising: causing motion of a field of view of an image sensor of said measuring instrument relative to said at least one target; capturing at least one digital image with said image sensor under motion of said field of view using an exposure time which is longer than an identifiable section of a regulating pattern for modulation of an optical radiation either emitted or reflected by said at least one target; and processing at least a portion of the captured image for detecting in said at least one portion the identifiable section of the regulating pattern.