A sampling apparatus (100) employs a cell-positioning system to move a sample capture cell (138) relative to a specimen positioning system (124). The cell-positioning system may be controlled to move sample capture cell (138) opposite to movement of the specimen positioning system (124) to maintain alignment of the sample capture cell (138) with an optical path of a laser beam of a sample generator (108). Alternatively or additionally, the cell-positioning system may be controlled to move sample capture cell (138) in response to alignment deviation of a reference beam on a quadrant detector (404).