Optical element exchange unit

Patent metadata

Field	Value
Publication number	US-12463519-B2
Application number	US-202017580806-A
Country	US
Kind code	B2
Filing date	Jul 24, 2020
Priority date	Jul 24, 2019
Publication date	Nov 4, 2025
Grant date	Nov 4, 2025

Abstract

An optical element exchange unit, has a rotatable wheel e.g. with different filters. The wheel has first soft magnetic teeth protruding from a soft magnetic part of the wheel at even angular offset along at least part of a ring around a rotation axis of the wheel. The optical element exchange unit has a stator comprising a first soft magnetic yoke, the first soft magnetic yoke having poles with a first group and second group of at least one second soft magnetic tooth respectively, the second soft magnetic teeth of the first and second group protruding from the poles of the first soft magnetic yoke towards the first soft magnetic teeth and a second soft magnetic yoke, the second soft magnetic yoke having poles with a third group and fourth group of at least one second soft magnetic tooth respectively, the second soft magnetic teeth of the third and fourth group protruding from the poles of the second soft magnetic yoke towards the first soft magnetic teeth. A permanent magnet is magnetically coupled between parts of the first and second soft magnetic yoke. The teeth of the first, second, third and fourth groups are positioned so that, when each tooth of the first group is aligned with its nearest first soft magnetic tooth, each second soft magnetic tooth of the second group is halfway the angular offset between its nearest first soft magnetic teeth, and the second soft magnetic teeth in the third and fourth group are less than half the angular offset in opposite directions from their nearest first soft magnetic teeth.

First claim

The invention claimed is:

1 . An optical element exchange unit, comprising:
a rotatable wheel, with at least two optical elements in or on the wheel, positioned so that different ones of the optical elements will be moved to intersect an optical axis of the optical element exchange unit by rotating the wheel, the wheel comprising first soft magnetic teeth protruding from a soft magnetic part of the wheel at an even angular offset along at least part of a ring around a rotation axis of the wheel; a stator comprising: a first soft magnetic yoke, the first soft magnetic yoke having poles with a first group and second group of second soft magnetic teeth respectively, the second soft magnetic teeth of the first and second group protruding from the poles of the first soft magnetic yoke towards the first soft magnetic teeth; a second soft magnetic yoke, the second soft magnetic yoke having poles with a third group and fourth group of second soft magnetic teeth respectively, the second soft magnetic teeth of the third and fourth group protruding from the poles of the second soft magnetic yoke towards the first soft magnetic teeth; wherein the teeth of the first, second, third and fourth groups are positioned so that, when each second soft magnetic tooth of the first group is aligned with its nearest first soft magnetic tooth, each second soft magnetic tooth of the second group is halfway the angular offset between its nearest first soft magnetic tooth, and the second soft magnetic teeth of the third and fourth group are less than half the angular offset in opposite directions from their nearest, respective, first soft magnetic teeth; a permanent magnet, magnetically coupled between parts of the first and second soft magnetic yoke,
wherein a part of the first soft magnetic teeth having a relatively narrower top width is located in ranges of angular positions where the second soft magnetic teeth face the wheel when respective ones of the optical elements intersect the optical axis respectively, and a further part of the first soft magnetic teeth located in between these ranges of angular positions have a relatively broader top width.

2 . The optical element exchange unit according to claim 1 , wherein only said first and second soft magnetic yoke are provided to drive rotation of the wheel.

3 . The optical element exchange unit according to claim 1 , wherein no permanent magnetic flux is applied to the first soft magnetic teeth other than permanent flux generated by said permanent magnet.

4 . The optical element exchange unit according to claim 1 , wherein the first soft magnetic teeth protrude radially from a rim of the wheel, and the second soft magnetic teeth protrude radially towards the rim of the wheel.

5 . The optical element exchange unit according to claim 1 , wherein a radial distance from the rotation axis of the wheel to the ring exceeds a maximal radial distance from the rotation axis of the wheel.

6 . The optical element exchange unit according to claim 1 , wherein the first soft magnetic teeth on the wheel and the second soft magnetic teeth on the first and second soft magnetic yokes are formed as ridges that protrude in a direction transverse to an elongation direction of the ridges.

7 . The optical element exchange unit according to claim 1 , wherein at least a part of the first soft magnetic teeth have in a pointed cross section protruding from the soft magnetic part of the wheel, with a relatively broader width nearer their base on the wheel and a narrower top further from their base.

8 . The optical element exchange unit according to claim 1 , wherein the optical elements are optical filters.

9 . The optical element exchange unit according to claim 1 , comprising first and second coils around the first and second soft-magnetic yoke respectively, configured to change a magnetic flux through the first and second soft-magnetic yoke respectively by electric current through the coils.

10 . The optical element exchange unit according to claim 9 , comprising a current supply control circuit coupled to the coils, configured to supply electric current pulses alternately through the first and second coils.

11 . The optical element exchange unit according to claim 10 , wherein the current supply control circuit is configured to keep the wheel at different stationary positions wherein different optical filters intersect the optical axis respectively, by ceasing electric current application to the coils around the first and second soft magnetic yoke.

12 . A satellite comprising an optical element exchange unit according to claim 1 .

13 . A method of rotating optical elements into an optical path, using an optical element exchange unit according to claim 1 , the method comprising applying electrical current pulses alternately through coils around the first and second soft-magnetic yoke respectively.

14 . A method of rotating optical elements into an optical path according to claim 13 , wherein the electrical current pulses are used to rotate the wheel between different stationary positions wherein different optical filters intersect the optical axis respectively, the wheel being kept in place at the different stationary positions by a holding force created by distributing the flux from one pole of the permanent magnet over the first and second group of second soft magnetic teeth and distributing the flux from the opposite pole of the permanent magnet over the third and fourth group of second soft magnetic teeth, while no electric current is applied to coils around the first and second soft magnetic yoke.

Assignees

• TNO

Inventors

• Kuiper Stefan
• Kooper Martin Paul Alfred

Classifications

• H02K2201/15

  Sectional machines · CPC title

• G02B26/008 Primary

  in the form of devices for effecting sequential colour changes, e.g. colour wheels · CPC title

• G02B7/006

  Filter holders · CPC title

• H02K1/246

  Variable reluctance rotors · CPC title

• H02K2201/03

  Machines characterised by aspects of the air-gap between rotor and stator · CPC title