Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
2001-07-09
2003-09-09
Robinson, Mark A. (Department: 2872)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
C359S214100, C359S368000
Reexamination Certificate
active
06618178
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an optical arrangement for deflecting a light beam in particular in two substantially mutually perpendicular directions, preferably for applying to confocal scanning microscopes.
BACKGROUND OF THE INVENTION
An optical arrangement of the generically determinative type is disclosed in DE 196 54 210 C2. The arrangement known from this printed publication for scanning a beam advantageously permits high scanning rates during deflection of the light beam.
Disadvantageous in the known arrangement are scanning errors which arise in the form of a hyperbolic distortion, particularly after the scanning of an object with a confocal scanning microscope. The distortion can certainly be corrected computationally, but is problematical under some circumstances since the image cannot be uniquely reconstructed computationally, particularly in the case of object scanning in which the scanning theorem is not fulfilled.
SUMMARY OF THE INVENTION
The object of the present invention is therefore to specify and develop a generically determinative arrangement for deflecting a light beam in two substantially mutually perpendicular directions in such a way that the distortion errors generated by the arrangement can be minimized and, in the ideal case, eliminated.
The above object is accomplished by the arrangement according to the invention which comprises: a first rotary drive defining a first axis of rotation, a second rotary drive defining a second axis of rotation, wherein the axes are mutually perpendicular, a first mirror rotated by the first rotary device, a second mirror rotated by the second rotary device, a third mirror arranged in an angular position with respect to the first mirror wherein the first and third mirror rotate jointly about the first axis, a pivot point is defined on the second mirror, wherein the light beam pivots about the pivot which lies on the second of rotation of the second mirror, and the first, second and third mirrors are arranged, that a light beam running between the second and the third mirrors and the second axis of rotation are always substantially in one plane and the plane is perpendicular to the first axis of rotation.
It is a further object of the present invention to specify a confocal scanning microscope which has an optical arrangement for deflecting a light beam in two substantially mutually perpendicular directions and eliminates distortion errors generated by the optical arrangement.
The above object is accomplished by a confocal scanning microscope comprising: an optical arrangement for deflecting a light beam in two substantially mutually perpendicular directions, the optical arrangement has a first rotary drive defining a first axis of rotation, a second rotary drive defining a second axis of rotation, wherein the axes are mutually perpendicular, a first mirror rotated by the first rotary device, a second mirror rotated by the second rotary device, a third mirror arranged in an angular position with respect to the first mirror wherein the first and third mirror rotate jointly about the first axis, a pivot point is defined on the second mirror, wherein the light beam pivots about the pivot which lies on the second axis of rotation of the second mirror, and the first second and third mirrors are arranged, that a light beam running the second and the third mirrors and the second axis of rotation are always substantially in one plane and the plane is perpendicular to the first axis or rotation.
An additional object of the invention is to provide a confocal scanning microscope which has a simple designed optical arrangement for deflecting a light beam in two substantially mutually perpendicular directions and thereby eliminating distortion errors generated by the optical arrangement.
The above object is accomplished by a confocal scanning microscope comprising: an optical arrangement for deflecting a light beam in two substantially mutually perpendicular directions, wherein the optical arrangement has a housing which accommodates a first, third and fourth mirror and a holding device which accommodates a second mirror and the holding device rotatable mounts the housing wherein the holding device and the housing are configured as replaceable modules.
According to the invention, it has been initially realized that the hyperbolic distortion named in DE 196 54 210 C2 can be minimized or eliminated whenever the rotation of the mutually assigned mirrors—first and third mirrors—, which rotate jointly about the first axis of rotation, deflect the light beam after reflection at the third mirror only along one direction or one straight line. Likewise, during rotation of the second mirror about the second axis of rotation the light beam need be deflected only along one direction or one straight line. Consequently, the decoupling of the rotation of the mirrors about their respective axes of rotation relative to the direction of deflection corresponding to the directions of deflection of the respective other axis of rotation is a fundamental precondition for deflecting the light beam with little distortion. The arrangement according to the invention of the first and third mirrors relative to the second mirror permits such a decoupling, since the optical axis of the light beam reflected by the third mirror and running to the second mirror always impinges on the second mirror, and the point of impingement of the optical axis of the light beam lies on the second axis of rotation of the second mirror and always lies in the plane perpendicular to the first axis of rotation in the way according to the invention during rotation of the two mirrors assigned to one another.
In a further advantageous way, the mirrors are arranged in such a way that the optical axis of the light beam running from the third mirror to the second mirror always impinges substantially at a point on the mirror surface of the second mirror which is the point of intersection of the two axes of rotation. Owing to this arrangement of the mirrors, when the first and third mirrors are rotated independently of the pivot angle thereof, the optical axis of the light beam reflected by the second mirror is always pivoted about the same point, and this advantageously maintains a telecentric beam path even downstream of the mirror arrangement. Since the point of impingement of the light beam reflected by the third mirror on the second mirror is always substantially the same independently of the angular position of the second mirror, with reference to the direction of deflection of the third mirror, as well, the light beam reflected or deflected by the third mirror is always pivoted about the point which lies on the mirror surface of the second mirror and is the point of intersection of the two axes of rotation. Consequently, the light beam deflected by the mirrors is deflected, in particular, in two substantially mutually perpendicular directions.
It is of no consequence for the mode of operation of the arrangement for deflecting a light beam whether the light beam to be deflected is a non-expanded or an expanded, or collimated, light beam.
In a concrete embodiment, the optical axis of the light beam incident on the first mirror, and the optical axis of the light beam reflected by the second mirror are substantially collinear. This holds, however, only when the second mirror is located in the non-deflected position, that is to say the second rotary drive rotating the second mirror is located in its rest position. The collinear arrangement of the optical axes is advantageous, in particular, for the adjustment and/or mounting of the arrangement since, without the three mirrors of the deflecting arrangement, the incident light beam points at the same point which results when the three mirrors of the deflecting arrangement are into the optical beam path. In a further embodiment, the axis of rotation of the first and third mirrors is substantially collinear with the optical axis of the light beam incident on the first mirror. The result is that, when the first and thi
Leica Microsystems Heidelberg
Robinson Mark A.
Simpson & Simpson PLLC
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