Diode laser device having a reflecting feedback element, and apparatus using the device
AssigneeU.S. Philips Corporation
InventorsCoen T. H. F. Liedenbaum, Ronald R. Drenten, Michiel J. Jongerius
Life of this patent
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Abstract
An optical device (7) for use in optical write, read, inspection or measuring apparatuses comprising a diode laser (8) for generating a radiation beam (11) and an optical system (9) for concentrating and guiding the radiation beam. The diode laser is a pulsed laser and a feedback element is arranged in the radiation path at a specific distance (d) from the diode laser. By giving the element a suitable reflection coefficient, a stabilized radiation beam is obtained. The beam direction can be varied by rendering the wavelength adjustable and by making use of a dispersive element.
Claims26
An optical device comprising a diode laser for generating a radiation beam, and an optical system for concentrating and guiding the radiation beam, characterized in that the diode laser is a pulsed laser which supplies radiation pulses at a pulse duration p and a pulse period T and in that an at least partially reflecting feedback element is arranged in the radiation path of the radiation beam at approximately a distance d from the diode laser, which distance d satisfies the condition ##EQU4## in which n is an integer, c is the light velocity in a medium traversed by the radiation beam, .DELTA.p is the build-up time of a pulse PL in the diode laser and .epsilon. is a real number which satisfies 0<.epsilon.<1 and increases or decreases within these limits at a decreasing or increasing energy E(P.sub.r), respectively, of a radiation pulse reflected by the feedback element so that the condition given by
- E(P.sub.r)>E(PL.sub.i)
- is satisfied at the instant when said radiation pulse enters the diode laser, E(PL.sub.i) being the radiation energy built up in the diode laser at the relevant instant.
Dependencies are inferred from the claim text.