Optical: systems and elements – Glare or unwanted light reduction
Reexamination Certificate
1999-03-25
2001-03-13
Sikder, Mohammad Y. (Department: 2872)
Optical: systems and elements
Glare or unwanted light reduction
C359S604000, C359S605000, C359S609000, C343S840000
Reexamination Certificate
active
06199988
ABSTRACT:
DESCRIPTION
TECHNOLOGICAL FIELD
The invention relates to a retractable device of the light shield type, designed to prevent the entry of parasitic light, coming from the sun or from any other light source, into an optical instrument such as a telescope, when this device is in an active configuration.
The device according to the invention finds a specially important application in the domain of space. In effect, when it is in its retracted configuration, its reduced volume is particularly suited to the compactness restrictions imposed at the time of a launch. On the other hand, its active configuration allows it to be operational when the space vehicle is on station.
STATE OF THE TECHNOLOGY
When an optical instrument must be fitted with a light shield, the most commonly used technique consists of using a rigid light shield integral with the instrument or attached onto it.
Within the field of space, use of rigid light shields is only possible in cases where a light shield is of small dimensions and in particular is of short length. In effect, when the dimensions of the light shield increase, these dimensions quickly become incompatible with the volume restrictions imposed during the launch. Hence, a rigid light shield of great length integral with an optical instrument cannot always by positioned in the reduced volume available under the nose cone of a launch vehicle.
For this reason, certain optical instruments put on board space vehicles have been equipped with retractable light shields. Such light shields have a retracted or folded configuration when they are placed under the nose cone of the launch vehicle. They are generally clamped by devices called “stacking” devices which allow them to bear the accelerations and the vibrations of the launch. When the space vehicle is separated from the launch vehicle, command devices allow the light shield to be brought into an active or deployed configuration.
In the present state of the technology, the retractable light shields which are fitted to optical instruments put on board space vehicles include mechanisms which can be relatively complicated, for example mechanisms of the pantograph or telescopic type. When one takes into account the particular constraint due to the space environment (lubrication in a vacuum, the mechanical loading during the launch, etc.) such mechanisms can be very expensive, notably for reasons of reliability.
DESCRIPTION OF THE INVENTION
The precise subject of the invention is a retractable device of the light shield type, whose particularly simple design and production allow it to be appreciably more economic and more reliable than existing retractable devices.
Conforming to the invention, this result is obtained by means of a retractable device, capable of hindering the entry of parasitic light through an opening of a given axis in an optical instrument, characterised by the fact that it comprises rods articulated about the optical instrument within planes containing said axis or parallel to it, a flexible and opaque covering carried by said rods and command means capable of causing the rods to pivot between a retracted configuration in which the covering is positioned around the optical instrument and an active configuration in which the covering extends beyond said opening.
In a preferred embodiment of the invention, the rods comprise first rods to which the covering is fixed and second rods mounted between the first rods and co-operating with the covering to hold it radially outwards between the rods, in the active configuration.
In a more precise fashion, in the active configuration, the first rods are directed approximately parallel to the axis of the optical instrument and the second rods deviate progressively from this axis beyond the opening of the optical instrument.
Depending on the case, a single second rod or at least two second rods are mounted between two consecutive first rods.
So as to hold the covering radially outwards between the first rods, in the active configuration, the second rods are preferably supported on a surface of the covering capable of being turned towards the axis of the optical instrument in this same active configuration.
When the device of the light shield type must have a symmetrical shape, the rods are spaced regularly about its axis and are approximately of the same length.
An asymmetrical device can however be obtained by giving the rods different lengths.
According to a first embodiment of the invention, in the retracted configuration the rods are situated in a plane perpendicular to the axis of the optical instrument.
According to a second embodiment of the invention, in the retracted configuration, the rods are directed approximately parallel to the axis of the optical instrument, around this axis short of the opening.
According to a third embodiment of the invention, in the retracted configuration, the rods deviate progressively from the axis of the optical instrument, around this axis, short of the opening.
Preferably each of the rods is formed from a single rigid section.
As a variant, each of the rods can also be formed from at least two rigid sections articulated end to end, in such a way that they fold one onto the other in the retracted position and in such a way as to be arranged in extension one from the other in the active configuration.
REFERENCES:
patent: 3558219 (1971-01-01), Buckingham et al.
patent: 3791713 (1974-02-01), Mackay
patent: 3978490 (1976-08-01), Fletcher et al.
patent: 4608571 (1986-08-01), Luly
patent: 4642652 (1987-02-01), Herbig et al.
patent: 4780726 (1988-10-01), Archer et al.
patent: 5198832 (1993-03-01), Higgins et al.
patent: 5954386 (1999-09-01), Thomas
Alcatel
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Sikd-er Mohammad Y.
LandOfFree
Retractable device, of the light shield type, for an optical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Retractable device, of the light shield type, for an optical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Retractable device, of the light shield type, for an optical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2516473