Optical: systems and elements – Single channel simultaneously to or from plural channels – By refraction at beam splitting or combining surface
Reexamination Certificate
2003-08-07
2004-11-09
Dang, Hung Xuan (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By refraction at beam splitting or combining surface
C359S636000, C359S831000, C359S834000
Reexamination Certificate
active
06816318
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a beam shaping device for shaping the cross section of a light beam comprising at least one beam shaping unit with beam division means, beam deflection means and beam combination means, the beam division means being able to divide a light beam incident on the beam shaping unit into two component beams, the beam deflection means being able to deflect at least one of the component beams to the beam combination means, and the beam combination means being able to combine the two component beams, such that the cross section of the light beam emerging from the beam shaping unit compared to the cross section of the light beam entering the beam shaping unit is reduced in the first direction and is enlarged in a second direction which is perpendicular to it. Furthermore, this invention relates to an arrangement for injecting a light beam with an elongated cross section proceeding from an elongated laser light source into an optical fiber, comprising a laser light source, a collimation unit which is located behind it in the beam direction, a beam shaping device of the aforementioned type and a focussing unit which is located behind the beam shaping device and which can focus the beam incident on it onto the optical fiber.
A beam shaping device of the aforementioned type and an arrangement of the aforementioned type are known from German patent DE 195 37 265 C1. In the embodiment of a beam shaping unit described in it a rhomboid prism pair which separates the incident radiation into two component beam bundles is used as the beam division means. The beam deflection means are two half cubic prisms which are integrated into the corresponding component beam paths, as a result of the relatively long path of the component beam bundle which has been traversed in this beam shaping unit there being a lens located between the rhomboid prism pair and the half cube prism. The beam combination means is a fifth prism which deflects the component beam bundles which are incident on it and combines them again.
The disadvantage in this beam shaping unit is that overall seven components are used, each of the individual component beams passing through eight optionally partially absorbing surfaces of optical components and being reflected each on two other surfaces of the aforementioned components, which surfaces may not be 100% reflective. Based on the many surfaces which must be transmitted or on which reflection must take place, a relatively great cost must be borne to coat the surfaces accordingly with respect to transmission or reflection. In particular, when several of these beam shaping units are set up in succession, such a beam shaping device will be less effective. Furthermore, as a result of the many components used and as a result of the high coating cost these beam shaping units will be extremely expensive.
An arrangement of the initially mentioned type is generally used whenever for example laser radiation proceeding for example from a laser diode bar is to be focussed on an optical fiber. In particular, as a result of the almost line-shaped laser light source with individual emission centers which are located spaced apart over the length of the line and the different divergences in the slow axis and fast axis direction, it is a good idea to use a beam shaping device of the initially mentioned type in order to repeatedly shape and combine the laser light emerging from the laser diode bar with an almost line-shaped cross section, so that a laser beam bundle with an almost square cross section is formed which then can be focussed more easily on the optical fiber. The effectiveness and economic efficiency of such an arrangement of course follow from the effectiveness and economic efficiency of the beam shaping device used in it.
One object of this invention is to devise a beam shaping device of the initially mentioned type and an arrangement of the initially mentioned type which are built efficiently and economically.
SUMMARY OF THE INVENTION
The beam combination means are also used as beam division means, only one of the component beams being deflected by the beam deflection means, conversely the other component beam being directly incident on the beam combination means. This measure drastically reduces the number of transmissions or reflections of the individual component beams. Furthermore, a beam shaping unit as claimed in the invention in the ideal case can consist of two individual optical components, conversely in the prior art for the same function seven components being necessary. In particular, one of the component beams will be incident directly on the beam combination means without prior passage through other optical components so that for this component beam the number of transmissions or reflections is minimized. Advantageously the second of the component beams for dividing the beam will run unhindered past the component which is being used as the beam combination means and the beam division means and will be deflected by the beam deflection means onto the functional sections of the component which is used as the beam combination means and the beam division means, which sections are used as beam combination means. This measure also minimizes the number of transmissions and reflections of the second component beam.
Advantageously the beam combination means comprise two specular surfaces which include an angle to one another, and each of the component beams which are to be combined by the beam combination means can be reflected on one of the specular surfaces. Especially for the case in which the specular surfaces are the outside surfaces of the beam combination means, each of the component beams will undergo only one reflection on this component, but not an additional transmission.
According to one preferred embodiment of this invention, there is a single prism as the beam combination means and at the same time the beam division means, the specular surfaces which reflect the component beams being made as preferably mirrored surfaces of this prism. Such a prism represents an especially simple but nevertheless very effective embodiment of the component which is used at the same time as the beam combination means and beam division means.
Advantageously the prism which is used as the beam division means and as the beam combination means can have a base surface which is made as an isosceles right triangle, the specular surfaces being those prism surfaces which each extend between the legs of the base surfaces so that the specular surfaces include an angle of 90° with one another. By choosing one such right-angled prism the desired beam combination function can be implemented most easily, in which specifically the two specular surfaces which are at an angle of 90° to one another are each aligned at an angle of 45° or −45° to the component beams which run from the opposite directions onto the prism.
Here the prism which is used as the beam division means or as the beam combination means can be located in the beam shaping unit such that the light beam which is incident on the beam shaping unit and which is to be shaped is cut in half in the first direction which is essentially perpendicular to the direction of propagation of the light beam, such that one of the two component beams which is formed by this halving runs past the prism onto the beam deflection means and the other of the two component beams which is formed by this halving is directly incident on the first of the two specular surfaces and is reflected by them in the direction of the light beam leaving the beam shaping unit. By this cutting of the beams in half on the prism the first of the two component beams in the entire beam shaping unit will ultimately undergo only one reflection on the first of the two specular surfaces and not transmission. The other of the component beams according to the choice of the beam deflection means will undergo two to four reflections or transmissions on the beam deflection means and exactly one reflection on the second specular surface, b
Dang Hung Xuan
Hentze-Lissotschenko Patentverwaltungs GmbH & Co. KG
Hoffman Wasson & Gitler PC
Martinez Joseph
LandOfFree
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