Optical assembly with translatable centered sleeve

Patent metadata

Field	Value
Publication number	US-9939604-B2
Application number	US-201615087433-A
Country	US
Kind code	B2
Filing date	Mar 31, 2016
Priority date	Mar 31, 2015
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

Optical assemblies include a barrel defining a cavity having a center axis, a sleeve inserted in the cavity, one or more optical elements mounted within the sleeve and a retaining ring inserted into the cavity and securing the sleeve. The sleeve engages the barrel inner wall through a thread engagement allowing a longitudinal displacement of the sleeve within the cavity. The retaining ring is also threadably engaged within the barrel, and the profile of the corresponding threads, as well as the spatial profile of a peripheral transversal surface of the sleeve engaging the retaining ring, are selected to provide centering of the sleeve with respect to the center axis of the cavity throughout the longitudinal displacement of the sleeve.

First claim

The invention claimed is:

1. An optical assembly, comprising:
a barrel defining a cavity having a center axis, the barrel comprising an inner wall provided with a first set of barrel threads and a second set of barrel threads;
a sleeve inserted in the cavity and having a forward end and a rearward end, the forward end comprising an outer wall provided with a set of sleeve threads engaging the first set of barrel threads so as to allow a longitudinal displacement of the sleeve within the cavity upon rotation of the sleeve, the rearward end of the sleeve comprising a peripheral transversal surface having a curved spatial profile;
at least one optical element mounted within the sleeve and centered with respect to the sleeve; and
a retaining ring affixed to the barrel through a set of ring threads engaging the second set of barrel threads, the retaining ring having an abutment engaging the peripheral transversal surface of the sleeve, the ring threads having a rearward thread face forming an effective thread angle with respect to a plane perpendicular to the center axis of the cavity,
wherein the effective thread angle of the ring threads and the curved spatial profile of the peripheral transversal surface are selected in view of an auto-centering condition whereby any decentering of the retaining ring and corresponding tilt of the retaining ring with respect to the center axis have counterbalancing effects on centering of the sleeve with respect to the center axis.

2. The optical assembly according to claim 1 , wherein the curved spatial profile of the peripheral transversal surface of the sleeve is characterized by a radius of curvature, and the auto-centering condition relates the effective thread angle and the radius of curvature according to:

d
ring

2
⁢

⁢

tan
⁡

(
ω
)

=

R
2

-

Y
2

+
h
+

T
⁢

/

⁢
2

where:
d ring is a diameter of the retaining ring along the ring threads;
ω is the effective thread angle of the second set of barrel threads and of the ring threads;
R is the radius of curvature of the peripheral transversal surface;
Y is a half-diameter of the abutment of the retaining ring;
h is the distance between (i) a first point of contact of the second set of barrel threads with the ring threads proximate to the sleeve and (ii) a point of contact of the abutment of the retaining ring with the peripheral transversal surface of the sleeve; and
T is the distance between (i) the first point of contact of the second set of barrel threads with the ring threads proximate to the sleeve and (ii) a last point of contact of the second set of barrel threads with the ring threads farthest from the sleeve and diametrically opposite to the first point of contact.

3. The optical assembly according to claim 1 , wherein the second set of barrel threads and the ring threads have a symmetrical thread profile characterized by a thread angle corresponding to twice the effective thread angle.

4. The optical assembly according to claim 3 , wherein the thread angle of the second set of barrel threads and of the ring threads has a value of 29°, 55° or 60°, and the peripheral transversal surface is adjusted to meet the auto-centering condition.

5. The optical assembly according to claim 3 , wherein the thread angle of the second set of barrel threads and of the ring threads has a value other than 29°, 55° or 60°, and adjusted to meet the auto-centering condition.

6. The optical assembly according to claim 1 , wherein the first and second sets of barrel threads have a same thread profile.

7. The optical assembly according to claim 6 , wherein the first and second sets of barrel threads form a continuous thread path along the inner wall of the cavity.

8. An optical assembly, comprising:
a barrel defining a cavity having a center axis, the barrel comprising an inner wall provided with a first set of barrel threads and a second set of barrel threads;
a sleeve inserted in the cavity and having a forward end and a rearward end, the forward end comprising an outer wall provided with a set of sleeve threads engaging the first set of barrel threads so as to allow a longitudinal displacement of the sleeve within the cavity upon rotation of the sleeve, the rearward end of the sleeve comprising a peripheral transversal surface having a spatial profile;
at least one optical element mounted within the sleeve and centered with respect to the sleeve; and
a retaining ring affixed to the barrel through a set of ring threads engaging the second set of barrel threads, the retaining ring having an abutment engaging the peripheral transversal surface of the sleeve, the ring threads having a rearward thread face,
wherein the rearward thread face of the ring threads and the spatial profile of the peripheral transversal surface extend perpendicularly to the center axis of the cavity.

9. An optical assembly, comprising:
a barrel defining a cavity having a center axis, the barrel comprising an inner wall provided with a first set of barrel threads and a second set of barrel threads;
a sleeve inserted in the cavity and having a forward end and a rearward end, the forward end comprising an outer wall provided with a set of sleeve threads engaging the first set of barrel threads so as to allow a longitudinal displacement of the sleeve within the cavity upon rotation of the sleeve, the rearward end of the sleeve comprising a peripheral transversal surface having a spatial profile;
at least one optical element mounted within the sleeve and centered with respect to the sleeve; and
a retaining ring affixed to the barrel through a set of ring threads engaging the second set of barrel threads, the retaining ring having an abutment engaging the peripheral transversal surface of the sleeve, the ring threads having a rearward thread face, an orientation of the rearward thread face of the ring threads and the spatial profile of the peripheral transversal surface being selected to provide a centering of the sleeve with respect to the center axis of the cavity throughout the longitudinal displacement of the sleeve within the cavity.

10. The optical assembly according to claim 9 , wherein the at least one optical element comprises a lens, a mirror, a diffractive optical element, a MOEMS, a DLP system, a detector, a camera, a prism, an optical fiber, a LCD, a laser source, a LED or a pinhole.

11. The optical assembly according to claim 9 , further comprising at least one fixed optical element mounted within the cavity, the longitudinal displacement of the sleeve within the cavity thereby changing a distance between the at least one fixed optical elem

Assignees

• Institut Nat Doptique

Inventors

• Lamontagne Frédéric
• Desnoyers Nichola

Classifications

• G02B7/003 Primary

  Alignment of optical elements (G02B7/001, G02B7/002 take precedence; for mirrors G02B7/1822) · CPC title

• G02B7/023 Primary

  permitting adjustment · CPC title

• G02B7/026

  using retaining rings or springs (G02B7/027 takes precedence) · CPC title