Optical: systems and elements – Lens – With support
Reexamination Certificate
2000-01-27
2001-08-07
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
With support
Reexamination Certificate
active
06271976
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns an apparatus for tilting an object about at least one axis, in particular an optical element, according to the preamble of claim
1
.
DESCRIPTION OF THE INVENTION
An apparatus of this type is described in DD 278 207 A1. Provided in the latter is a mount with adjusting elements, on which individually mounted optical elements are arranged in a nested-cell mounting tube. The adjusting elements comprise two annular disks which are directly adjacent to one another and can be rotated one in the other and independently of one another. Rotations of the annular disks, which form a pair of tapered rings, allow a defined inclination of the optical axis of the optical element to be set. In this way, the optical axes of individual optical elements can be aligned with great accuracy with respect to the mechanical axis of a lens system. An apparatus of this type allows alignment of the optical axis of an individual optical element that does not coincide with the optical axis of the lens system in which the optical element is fitted.
The skewed position of an optical axis of an optical element may be caused, for example, by production inaccuracies or flange unevennesses of an outer ring. The adjusting elements according to DD 278 207 A1 allow deviations of the optical axes of optical elements from the axis of the lens system to be corrected, but not with the great accuracy required for lens systems for semiconductor lithography, since the adjustment with the pair of tapered rings is affected by friction and consequently so-called stick-slip and hysteresis effects occur, resulting in “over”correction. Therefore, a slightly greater adjustment than desired is always set. Moreover, in the case of the known apparatus the optical element is not, however, isolated in terms of deformation from the outer mount, so that stresses and deformations on the flange are transferred to the optical element.
SUMMARY OF THE INVENTION
The present invention is based on the object of improving an apparatus of the type mentioned at the beginning in such a way that an object, in particular an optical element, can be swiveled very accurately at least about one axis, but in particular about two axes, it also being intended for the object to be at the same time isolated in terms of deformation from its mount or its outer ring.
This object is achieved according to the invention by the features stated in the defining part of claim
1
.
According to the invention, the inner ring, which bears the optical element, is now connected to the mount or the outer ring via a total of six links. Four links serve in this case as so-called supporting links in such a way that the inner ring can rotate only about the two mutually perpendicular tilting axes. The two other links, which act as adjusting links, respectively support the torsional moments about the two tilting axes (x axis and y axis) and serve at the same time for setting and adjusting the tilting angles. The links consequently have the effect that the mounting of the inner ring is statically determined, isolation of the inner ring from the outer ring in terms of deformation being simultaneously achieved in this way. Since the two tilting axes are mutually perpendicular, the tilting movements do not influence one another, for which reason subsequent corrects are not necessary when an adjustment is made in one direction.
If, in a very advantageous design of the invention, it is provided that the two tilting axes extend through the z axis, i.e. through the optical axis when the object is an optical element, a vertical offset of the optical element during tilting is avoided.
The supporting links may be designed in any way desired. For example, solid joints, ball joints or the like may be used for this purpose, it being possible for the connection to the inner ring and the outer ring to take place in each case via a joint or an adjustable or compliant connection.
In the case of tilting manipulators, which are known from practice and are based on a three-point or hexapod mounting of the inner ring in the outer ring, during tilting the optical element undergoes a vertical offset because of the tilting axes being askew with respect to the optical axis and this has to be rectified by subsequent tilting about other tilting axes. Since, the two tilting axes can intersect the optical axis of the optical element in the apparatus according to the invention, in this case no axial offset takes place during tilting.
In the case of known tilting manipulators, apart from cardanic suspensions, the tilting movements still influence one another, since the tilting axes are not mutually perpendicular. In the case of the apparatus according to the invention, on the other hand, the tilting axes are mutually perpendicular, so that the tilting movements do not influence one another.
According to the invention, the adjusting range is chosen such that it is possible to correct the tilting angle between the inner ring and outer ring produced by the statically determined mounting when there is deformation of the outer ring, for example due to the outer ring being screwed onto an uneven underlying surface. Also conceivable is deliberate tipping of the inner ring, tipping generally being restricted to relatively small angular ranges for reasons of practicability, for example solid joints.
REFERENCES:
patent: 3917385 (1975-11-01), Caswell
patent: 3989358 (1976-11-01), Melmoth
patent: 4298248 (1981-11-01), Lapp
patent: 5353167 (1994-10-01), Kuklo et al.
patent: 5986827 (1999-11-01), Hale
patent: 6191898 (2001-02-01), Trunz et al.
patent: 278 207 A1 (1990-04-01), None
patent: 235134-A (2000-08-01), None
Carl-Zeiss-Stiftung
Epps Georgia
Seyrafi Saeed
Welsh & Katz Ltd.
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