Supports – Machinery support – Movable machine
Reexamination Certificate
1999-09-23
2001-07-31
Ramirez, Ramon O. (Department: 3632)
Supports
Machinery support
Movable machine
C359S849000
Reexamination Certificate
active
06267348
ABSTRACT:
The invention concerns a device for the micrometric positioning of a support for an optical element integrated into a space system, namely a system designed to be launched into space, for example an artificial satellite, an orbital station or a planetary probe etc.
Space systems often incorporate optical systems, for example for the reception of images (planetary or astronomical observations), or even sometimes for the emission of rays or light signals etc. Now, the efficiency and precision of these optical systems are closely linked to the correct positioning of the optical elements of which they consist, with respect to a frame secured to the space system.
Certain on-board optical systems include so-called active optical elements which can be adjusted in space from the ground. These systems are sophisticated, heavy and bulky and thus extremely costly and are reserved for special applications (for example astronomical observations) for which mobility and adjustments in operation are imperative.
On the other hand, many optical systems integrated into space systems include so-called passive optical elements, namely those which are adjusted and fixed with respect to the frame on the ground and of which the position may not be adjusted in flight. The problem which such optical systems presents is then that of the precision of the initial adjustment on the ground and the maintenance of this adjustment during take-off phases (during which the system must be able to withstand high accelerations typically of 30 g or more), and then in space in the absence of gravity. Now, although these adjustments may be easily carried out with one, two or three degrees of freedom (for example for the centering of a spherical mirror), or with low precision (above 10 &mgr;m), the problem exists of positioning such an optical element on the ground with a precision of the order of a micron and with six degrees of freedom. This problem in particular exists for the positioning of aspherical mirrors of a planetary observation telescope of which faults in positioning cannot be compensated for by decentering as for telescopes with spherical mirrors, and which must permit very fine resolutions to be obtained.
The invention thus aims at overcoming these disadvantages by providing a device for the micrometric positioning with six degrees of freedom of an optical element with respect to a frame of a space system permitting adjustment on the ground with high precision, locking in position and maintenance in position during take-off and in space, precision being preserved.
The object of the invention is also to obtain this positioning in a simple, low-cost manner with a low weight and a low overall size of the parts integrated into the space system.
The object of the invention is more particularly to provide a micrometric positioning device for the mirrors of a telescope with aspherical mirrors integrated into an earth observation satellite.
To this end, the invention concerns a device for the micrometric positioning, with respect to a frame, of a support for an optical element designed to be integrated into a space system, wherein it comprises three mountings secured to the frame and, for each mounting:
first means of adjustment in translation along a first direction, of a first position of the support with respect to the mounting,
second means of adjustment in translation along a second direction, at least substantially orthogonal to the first direction, of a second portion of the support with respect to the mounting,
third means of micrometric adjustment in translation along a third direction, at least substantially orthogonal to the first and the second direction, of a third portion of the support with respect to the mounting, these third means of micrometric adjustment including means for the micrometric measurement of the distance separating the third portion of the support and a facing portion of the mounting,
the different first, second and third means of adjustment of the different mountings being adapted so as to be able to support and hold the support and the optical element in place with respect to the frame, and to permit adjustment of the position of the support with respect to the frame with six degrees of freedom,
means for locking the support in an adjusted position with respect to the frame comprising:
at least one locking screw associated with the support and the mounting via connecting means adapted so as to be compatible with different relative positions and orientations which can be assumed by the support with respect to the mountings, taking into account the accepted ranges for the amplitudes of adjustment for the different means of adjustment of the different mountings, the locking screw and the connecting means being adapted so as to lock, after tightening, the mounting and the support in position with respect to each other,
at least one shim of which the thickness is determined as a function of the distance measured between the third portion of the support and the facing portion of the mounting, this shim being placed so as to fill entirely, with the said connecting means, the distance separating the mounting from the support about the locking screw,
so that the position of the support with respect to the frame may be adjusted on the ground with a high degree of precision with six degrees of freedom, and then locked with locking screws enabling this adjusted position to be maintained during the launch of the space system and in space.
The possibilities of adjustment along three orthogonal directions at the level of three distinct mountings permit adjustment of the support and the optical element with six degrees of freedom.
Moreover, locking with the aid of a locking screw and with shims of which the thicknesses, determined by a micrometric thickness measurement, enables the optical element to withstand take-off and flight phases without loss of adjustment.
In all the present application, the expression “at least substantially along a direction” encompasses this direction and directions making an angle with this direction of less than or equal to the permitted angular variations for the support with respect to this direction in the accepted ranges for the adjustment amplitudes for the different means of adjustment. It should be noted in this respect that, given that the device permits micrometric positioning, the amplitudes of the adjustments are small, so that the three directions in space may be defined, in an equivalent manner for the general kinematics of the device, either with reference to the support or with reference to the frame. The support is moreover adapted so as to define reference and supporting planes for the means of adjustment which are parallel in a nominal position (corresponding to the position of the support with respect to the frame such as defined theoretically if all the parts and assemblies were perfect) to the reference and supporting planes of the means of adjustment of the frame.
In this way, the said first, second and third directions may be defined and fixed with respect to the frame or with respect to the support. Preferably, these three directions are defined and fixed with respect to the frame.
In addition, the first, second and third directions designate the geometric directions common to the three mountings.
The first, second and third directions are three directions at least substantially orthogonal two-by-two, i.e. they are normally orthogonal two-by-two in a nominal position of the optical element with respect to the frame, but one or more of them may not satisfy, in certain positions, this condition of strict orthogonality in variants where at least one direction is defined and fixed with respect to the support while at least one other direction is defined and fixed with respect to the frame.
Accordingly, the main condition which the three directions and the different means of adjustment must satisfy is to permit relative movements in at least one certain amplitude range, permitting the micrometric positioning of the optical element in its optimum
Centre National d'Etudes Spatiales (C.N.E.S.)
DeLuca J.
Ramirez Ramon O.
Young & Thompson
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