Device for displacing an optical element along the optical axis

Details Device for displacing an optical element along the optical axis Device for displacing an optical element along the optical axis

2000-02-14

2001-08-14

Mack, Ricky (Department: 2873)

Optical: systems and elements

Lens

With support

C359S819000

Reexamination Certificate

active

06275344

ABSTRACT:

The invention relates to a device for displacing an optical element along the optical axis according to the type defined in more detail in the preamble of claim
1
.
JP 83 13 785 A discloses a device of the type mentioned at the beginning in which a coarse drive with a pinion and a gear rack is provided for displacing a lens along the optical axis, and a piezoelectric element is provided for fine adjustment.
The use of piezoelectric elements for displacing lenses in objectives is also known from JP 080 94 906 A, U.S. Pat. No. 5,675,444 A and U.S. Pat. No. 5,576,894 A.
For the purpose of setting an objective or influencing its image errors etc., such as setting a magnification, for example, it is to be possible to adjust an optical element, for example a lens, along the optical axis in a very sensitive fashion and also with very short paths. Particularly in the case of large diameters of the optical element, such as 200 mm and more, for example, the problem consists, on the one hand, in that a large mass of the optical element has to be moved, and that, on the other hand, transverse movements, that is to say movements of the optical element transverse to the optical axis, are to be prevented as far as at all possible. The aim is also to prevent tilting, in particular about an axis perpendicular to the optical axis.
It is therefore the object of the present invention to create a device of the type mentioned at the beginning by means of which particularly large and weighty optical elements can be displaced very precisely and sensitively in the direction of the optical axis, specifically without the risk of transverse movements.
This object is achieved according to the invention by means of the features named in the characterizing part of claim
1
.
The configuration according to the invention results in a high stiffness transverse to the optical axis, whereas there is a satisfactory softness in the direction of the optical axis. Owing to the use of solid joints according to the invention, it is possible to produce a connection of the supporting ring with the retaining ring, the desired stiffness ratios being given. The supporting ring and retaining ring are, of course, not limited to cylindrical parts, but directed toward conventional parts for mounting an optical element.
A particularly advantageous solution results when the retaining ring and the supporting ring are constructed in one piece together with solid joints situated therebetween. This measure effects an excellent reduction in hysteresis (slip-stick) and stresses.
A very precise displacement without transverse movements is achieved when at least three solid joints are arranged distributed over the circumference between the retaining ring and the supporting ring. It is advantageous in this case also to assign an adjusting device to each solid joint. If, in addition, sensors are also provided, by means of which the position or alignment of the retaining ring is monitored, the optical element can be exactly displaced, in which case the optical axis of the lens also remains constantly on the optical axis of the overall system. Consequently, instability of the bearing against tilting is avoided by the arrangement according to the invention with at least three solid joints and corresponding drives. When the sensors are coupled to the adjusting devices, the optical element can be moved very uniformly by control loops or a closed loop.


REFERENCES:
patent: 4017878 (1977-04-01), Hagiwara
patent: 4161120 (1979-07-01), Cloarec
patent: 4878214 (1989-10-01), Hinotani
patent: 5576894 (1996-11-01), Kuwana et al.
patent: 5675444 (1997-10-01), Kuwana et al.
patent: 08094906A (1996-04-01), None
patent: 8313785 (1996-11-01), None

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