Electric heating – Metal heating – By arc
Reexamination Certificate
2000-07-17
2001-12-11
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
C219S121780
Reexamination Certificate
active
06329634
ABSTRACT:
The invention relates to a workpiece irradiation system which has several individually adjustable deflecting devices, and in which several spatially mutually separated individual processing beam pencils are respectively deflected separately, by means of the deflecting devices arranged in the optical beam path, to at least one workpiece to be irradiated, at variable points or surfaces on the workpiece.
A workpiece irradiation system of this kind is known, in particular, from DE 195 13 354, DE 44 40 117, and DE 197 07 834.
The measurement for the calibration of a segment mirror field at present takes place by means of (laser) beams, with which material processing is also carried out; if necessary, the intensity of the beams is weakened at suitable places so that measuring elements, in this case a CCD camera, are not damaged. This method has the advantages that:
no additional laser is required, and
no substantial distortions of the beam paths takes place, since the light used for measurement has the same wavelength as the light of the processing beam pencils and thus can be conducted, error-free, through the same optical components. (If the measuring beam pencil were to have another wavelength, it would be differently refracted by the given optics and would no longer be finally imaged on the CCD camera).
This method is used as long as the wavelength of the processed laser light can be processed by the CCD camera without problems. Thus, because of the required large-surface CCD array, it is:
technically simple and inexpensive in the wavelength range of 400 up to 1,000 nm,
technically more demanding and dearer in the wavelength range of 200-400 nm,
technically very demanding and very dear in the wavelength range of 1,000-5,000 nm, and
technically extremely demanding and extremely dear in the wavelength range of 5,000 up to 20,000 nm.
The usual wavelengths for material processing in the printed circuit industry are at present 248 nm (excimer laser), 355 nm (frequency-tripled YAG laser) and 9,600 nm (CO
2
laser). The known principle thus lies just at the boundary of economical practicability for the two UV wavelengths. For the CO
2
laser, for technical and economic reasons, no solutions are possible which can be realized in mass production equipment.
The invention has as its object to provide a workpiece irradiation system in which the position of the tilting devices, in particular in a segment mirror field, can be determined independently of the wavelength of the light beam pencils used for the workpiece irradiation system.
This object is attained according to the invention by the features of claim
1
. Advantageous embodiments of the invention will become apparent from the features of the dependent claims.
The workpiece irradiation system according to the invention has several independently adjustable deflecting devices, and several, mutually spatially separated, individual processing beam pencils are deflected, respectively separately, onto at least one workpiece to be irradiated, at variable points or surfaces on the workpiece.
The system is distinguished in that an additional beam source is arranged in the workpiece irradiation system for the production of at least one measuring beam pencil, such that the measuring beam pencil emitted by the additional beam source is simultaneously incident on several deflecting devices, and that a measuring receiving device which is sensitive to the wavelength of the measuring beam is arranged in the workpiece irradiation system such that it receives at least a portion of the measuring beam pencil, deflected by the irradiated deflecting devices, for the detection of the deflecting action of the deflecting devices.
Preferably, in a first variant of the invention, a first optical member is installed before the deflecting devices in the optical beam path of the processing beam pencils, and allows the processing beam pencils to be incident on the deflecting devices and couples the measuring beam pencils into the optical beam path of the processing beam pencils in the direction toward the deflecting devices, and a second optical member is installed after the deflecting devices and allows the processing beam pencils to be incident on points or surfaces on the workpiece, and couples at least the measuring beam pencils out of the optical path of the processing beam pencils in the direction toward the measuring receiving device. The optical members can in particular be dichroic mirrors or dichroic beam splitter cubes.
Preferably here at least one of the two optical members can be removed from the optical beam path of the processing beam pencils.
In a further variant of the invention, the measuring beam pencils are preferably incident on the deflecting devices at another angle than the processing beam pencils, so that the radiation source for the production of the measuring beam pencil and the measuring receiving device can be arranged laterally of the optical beam path of the processing beam pencils.
An evaluation device is to be connected at least to the receiving device, and compares a stored or predetermined reference state with the actual state measured with the evaluation device.
It is advantageous for reasons of cost for the wavelength of the measuring beam pencils to be situated in the visible wavelength region, particularly when the wavelength of the processing beam pencils is situated in the infrared or ultraviolet wavelength region.
A simple realization of the invention is obtained when each deflecting device consists of a tilting mirror.
The deflecting devices are preferably adjustable by motors.
The deflecting devices can be realized as tilting devices with respective tilting members. If these have mirror surfaces, they can also be termed tilting mirrors, the tilting mainly taking place in one or two axes. The deflecting devices are to be embodied respectively separate from each other, in order to make certain a more secure beam guidance for each processing beam pencil, independently of the other processing beam pencils. This means nothing more than that each individual processing beam pencil is deflectable by a respective one tilting mirror which is allocated only to the respective individual deflecting device, where the deflection preferably corresponds to a reflection.
The measuring beam pencil must not be incident on the whole surface of the deflecting device, but can only be incident on a portion (preferably, a reflecting portion).
The deflecting device can be a tilting device with a tilting member, the front side of which is preferably at least partially mirror-finished, and the measuring beam is then incident on this mirror-finished surface for the measurement.
If a projection objective, preferably a F-TETA objective, is arranged between the deflecting devices and the workpiece surface, for the focusing of the workpiece irradiation pencil, the workpiece irradiation pencil is then very precisely focused on the workpiece surface, and by the use of the F-TETA objective, the irradiation of the workpiece takes place always about parallel to the optical axis of the projection objective.
An observation objective is to be arranged in front of the measuring receiving device, and assists in effecting the required measurement as quickly as possible at the required precision.
When the surface of the mirror arrangement is undivided as first and/or second optical members, it can then move with a higher positioning accuracy.
In order to minimize positioning errors, the first optical member forming the first mirror arrangement was to be partially transparent, and in fact reflective for the wavelength of the beam pencils irradiating the workpiece and transparent for the wavelength of the measuring beam pencil.
A second optical member forming a second mirror arrangement is preferably installed after the tilting devices which serve as deflecting devices, and deflects the measuring beams onto the measuring receiving device. This second mirror arrangement is preferably removable, e.g., pivotable, from the beam path of the workpiece irradiating beam pen
Carl-Zeiss-Stiftung
Heinrich Samuel M.
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