Optical: systems and elements – Single channel simultaneously to or from plural channels
Reexamination Certificate
2000-06-21
2001-08-28
Mack, Ricky (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
C359S641000
Reexamination Certificate
active
06282028
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a beamsplitter for splitting a light beam and including a plurality of reflecting surfaces arranged in a path of a collimated light beam and inclined to a propagation direction of the collimated light beam at an angle of 45° for splitting the collimated light beam into a plurality of output beams extending perpendicular to each other. The present invention also relates to an optical alignment tool including the above-described beamsplitter.
2. Description of the Prior Art
In the constructional industry, optical devices, which are based on the use of luminous, collimated light beams, are replacing more and more the known since long ago, mechanical devices which provide, by using a visual control, for alignment and measurement of positional accuracy of constructional elements, built-in elements, installations and so forth. Since the time the semiconductor industry was able to provide a large number of laser diode capable of emitting light in the visible spectrum, usually red, a number of measuring devices, which replaced the previously known mechano-visual devices and which offered new measurement possibilities, found their application in the constructional industry. Thus, alignment tools, which are capable of emitting a collimated laser ray beam having a distance range up to about 20 m, a maximum diameter of about 10 mm, and a deviation from a horizontal propagation of about 1 mm per 10 m, have found a wide acceptance. In these tool, a horizontal alignment of the laser ray beam takes place, as a rule, automatically due to the influence of the gravitational force of the construction itself or due to the use of an appropriate control circuit.
In addition to a horizontal alignment and leveling, there exists a need in the constructional industry to determine plumb or to mark an exact right angle. U.S. Pat. No. 5,144,487 discloses a laser alignment device for performing the above-mentioned tasks. The known laser device is capable of emitting three laser ray beams lying in a common horizontal plane and extending at a right angle to each other. In addition, the tool emits also two plumb beams. To generate horizontal and plumb laser ray beams, a plurality of mirrors are arranged inside the tool and which deviate a primary laser ray beam, which is emitted by a laser diode, in the desired directions. The deviating mirrors, which produce altogether five horizontal and plumb beams, are arranged in a path of the primary laser ray beam in a spaced relationship to each other. Because of the mirror arrangement, the three-dimensional system of coordinates, which is formed by the emitted laser ray beams, has a zero point displacement or error. This is because the horizontal beams and the plumb beams have different virtual origins. Up to the present, the manufacturers of such laser devices dealt with this problem by providing constructively for a zero point displacement of about 20 mm. This zero point displacement or error should be taken into account when effecting measurements with the known laser devices. During the use of these laser devices, failure to take the zero point error into account presents a not insignificant source of an erroneous measurement. Further, the mirrors for forming output beams from the primary laser ray beam need be precisely aligned which makes the assembly of the device rather difficult. In addition, the arrangement of separate mirrors is rather sensitive to shocks which presents a serious drawback, in particular when the device is used on a constructional site.
Accordingly, an object of the present invention is a beamsplitter for splitting a primary light beam in a plurality of separate beams without a zero point error of the separate beams.
Another object of the present invention is a beamsplitter which could be easily mounted in an optical alignment tool, in particular, in a laser alignment tool.
A further object of the present invention is a beamsplitter having a rigid construction and capable of being used on a constructional site.
SUMMARY OF THE INVENTION
These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a beamsplitter for splitting a light beam in a plurality of separate beams and including at least two reflecting surfaces inclined each at an angle of 45° to a propagation direction of a collimated primary light beam emitted by a light source, forming a right angle with each other, located at the same distance from a collimator for collimating the primary light beam, and extending into a path of the collimated light beam so that they emit two output beams. The inventive beamsplitter further includes a light passage provided in a space between the reflecting surfaces and extending substantially symmetrical to an optical axis of the collimator for enabling passing through the light passage a central portion of the collimated primary light beam.
The arrangement of reflecting surfaces in the path of the primary light beam permits to easily produce three output beams extending perpendicular to each other. The output beams, which are reflected from the reflecting surfaces, form, e.g., the orthogonal y- and z-axes. The central portion of the primary light beam, which passes unhindered through the beamsplitter, forms the x-axis. A system of Cartesian coordinates, which is produced in a manner described above, has a common virtual origin which is formed by the point of intersection of the extensions of the reflected output beams with the primary light beam a central portion of which passes through this intersection point. The position of the intersection point corresponds to the distance of the reflecting surfaces from the collimator. This completely eliminates the zero point error. The arrangement of reflecting surfaces at a right angle to each other and at the same distances from the collimator permits to obtain a robust construction of the optical element and facilitates mounting of the beamsplitter in an optical alignment tool. The sensitivity of the constructions to shocks is substantially reduced.
In order to eliminate an undesired reflection and to obtain precisely defined output beams, advantageously the alignment tool, in which the beamsplitter is mounted, includes a parting elements which separates the collimated primary light beam, before its splitting into a plurality of output beams, in a plurality of parallel primary separate beams.
In accordance with one embodiment of the present invention, the parting element is formed as an apertured diaphragm, which is arranged between the collimator and the beamsplitter, and the number of opening formed therein corresponds to the number of the reflecting surfaces of the beamsplitter increased by one. The provision of the additional opening takes into account the fact that in addition to the reflected output beams, a portion of the primary light beam passes unhindered through the beamsplitter for forming a third coordinate of the system of the Cartesian coordinates. Also, the openings of the apertured diaphragm permits to produce output beams with precisely determined diameters.
In accordance with a simplest embodiment of the present invention, the parting element is formed of a light-absorbing areas which surround each of the reflecting surfaces and which are formed by, preferably, vapor metal deposition. With this embodiment of the present invention, the spatial delimitation of separate primary beams is effected at the reflection regions, and a need in a special, separate parting element is eliminated.
In accordance with an advantageous embodiment of the present invention, the beamsplitter has four reflecting surfaces extending at a right angle to each other and arranged, preferably in a square. The four reflecting surfaces are equidistantly spaced form the collimator and extends into the path of the primary light beam so that the central portion of the primary light beam passes substantially unhindered through a central region of the beamsplitter defined by the ref
Bünter Erwin
Piske Wilfried
Waibel Reinhard
Hilti Aktiengesellschaft
Mack Ricky
Sidley Austin Brown & Wood LLP
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