摘要 |
A perforated shutter (10) at or near the waist end of the beam (2) in the light path ahead of the objective (4) has a smaller diameter in at least one direction than the beam waist, the shutter sited close to the outlet aperture of the semi-conductor laser (8). In a variant, a second objective is inserted between laser and shutter to produce the beam waist. The aperture of the shutter should be circular or elliptical and rotation-symmetric. The shutter should have variable aperture of several shutters each with aperture of different diameter and/or shape. Shutter and objective are so arranged in the light path and so dimensioned that the main maximum of the intensity spread strikes the objective rather than the minimum values of this intensity spread.
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