FIBER POSITIONING UNIT FOR TELESCOPES

Abstract

Fiber positioning unit of SCARA type comprising an alpha (1,2,3) and a beta mechanism (4,5); the alpha mechanism successively comprising a motor (1), a driving shaft (2) and a rotatable shaft (3), the rotation of the rotatable shaft (3) being carried out by the alpha motor (1) via the driving shaft (2); the beta mechanism comprising a motor (4) and a fiber holding element (5) that may be rotated by the beta motor (4); both mechanisms being mechanically connected in a way to allow a rotation of the beta mechanism (4,5) by the rotatable shaft (3); the alpha mechanism (1,2,3) being furthermore adapted to be partially located within a focal plate (6), characterized by the fact that the alpha motor (1) is adapted to be located on one side of the focal plate (6) while the rotatable shaft (3) and the beta mechanism (4,5) are adapted to be located on the other side of the focal plate (6).

Claims

1. Fiber positioning unit of SCARA type comprising an alpha and a beta mechanism; the alpha mechanism successively comprising a motor, a driving shaft and a rotatable shaft, the rotation of the rotatable shaft being carried out by the alpha motor via the driving shaft; the beta mechanism comprising a motor and a fiber holding element that may be rotated by the beta motor; both mechanisms being mechanically connected in a way to allow a rotation of the beta mechanism by the rotatable shaft; the alpha mechanism being furthermore adapted to be partially located within a focal plate, characterized by the fact that the alpha motor is adapted to be located on one side of the focal plate while the alpha rotatable shaft and the beta mechanism are adapted to be located mainly on the other side of the focal plate.

2. Fiber positioning unit according to claim 1 wherein the rotatable shaft at least partially extends through the focal plate.

3. Fiber positioning unit according to claim 1 wherein the motor diameter (alpha or beta) is comprised between 2 and 6 mm.

4. Assembly comprising a focal plate and several fiber positioning units as defined in claim 1, the focal plate comprising passages with different diameters, wherein the greatest diameter is approximatively equivalent to the diameter of the driving shaft.

5. Assembly according to claim 4 wherein the motor diameter (alpha or beta) is similar to the pitch.

6. Assembly according to claim 4 wherein said focal plate consists of a plurality of sub-modules.

7. Assembly according to claim 5 wherein each sub-module has a polygonal cross section, for instance a triangular section.

8. Method for assembling fiber positioning units as defined in claim 1 on a focal plate wherein the alpha motor is inserted and fixed on one side of the focal plate and wherein the beta mechanism is positioned and fixed on the other side of the focal plate.

9. Method according to claim 1 wherein the alpha motor and the beta mechanism are mounted on the focal plate in two distinct and independent steps.

Description

LIST OF FIGURES

[0019] FIG. 1: Prior art FPU of the SCARRA type

[0020] FIG. 2: Other example of a prior art FPU

[0021] FIG. 3: Front view of a prior art focal plate

[0022] FIG. 4: Graph showing the density of FPU on a focal plate

[0023] FIG. 5: Other example of a prior art FPU

[0024] FIG. 6: Other example of a prior art FPU

[0025] FIG. 7: Other example of a prior art FPU

[0026] FIG. 8: Mounting of a FPU on a focal plate

[0027] FIG. 9: Example of a FPU according to the invention

[0028] FIG. 10: Front view of a focal plate according to the invention

[0029] FIG. 11: Other view of the FPU of FIG. 9

[0030] FIG. 12: Other view of the FPU of FIG. 9

NUMERICAL REFERENCES USED IN THE FIGS. 9 TO 12

[0031] 1. Alpha motor [0032] 2. Driving shaft [0033] 3. Hollow rotatable shaft [0034] 4. Beta motor [0035] 5. Fiber holding element [0036] 6. Focal plate [0037] 7. Driving shaft passage [0038] 8. Optic fiber passage [0039] 9. Electric wire passage [0040] 10. Optical fiber [0041] 11. Beta motor electric wire

[0042] FIG. 9 shows an example of a FPU according to the invention with the optical fiber being straight and placed between two adjacent alpha motors 1.

[0043] The FPU according to the present invention provides the following advantages: [0044] The focal plate 6 may be more easily manufactured. [0045] Assembling the FPUs on the focal plate 6 does not require any complex process. [0046] FPUs are preferably screwed, the alpha motor 1 being inserted on one side of the focal plate 6 and held in position by friction and the beta mechanism 4,11 being positioned and fixed on the other side of the focal plate 6. A press fitted pin may be advantageously used to avoid rotation of the motor. (No glue or laser welding are required). [0047] The alpha rotatable shaft 3 and the beta mechanism 4,11 are on the same side of the focal plate 6, the passages 7,8,6 within the focal plate 6 are therefore relatively small, which results in a more robust structure. [0048] It is possible to test the performances of each positioner before assembling it on the focal plate 6.