US 2020/0264402 A1Published application

Centering of an optical element using edge contact mounting

AssigneeInstitut National D'Optique

InventorsMaxime SAVARD, Frédéric LAMONTAGNE

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Abstract

Optical assemblies are provided in which an optical element is centered in the cavity of a barrel. The optical element is secured between a seat in the cavity and a retaining ring. The retaining ring has ring threads complementary to the barrel threads. The retaining ring has an abutment surface engaging a peripheral mounting edge of the optical element along a circular edge contact line. In some embodiments, the abutment surface has a frustro-spherical profile having a radius of curvature selected in view of the thread angle to maintain a centering of the optical element even when the retaining ring is decentered in the cavity. In other variants, the abutment surface has a frustro-conical profile having an inclination angle with respect to the center axis of the cavity selected in view of the thread angle to maintain said centering.

Claims22

Dependent claims

An optical assembly, comprising:

a barrel having a cavity and a set of barrel threads;
a seat provided in the cavity of the barrel;
an optical element having a first surface resting on the seat and a second surface opposite to the first surface, said optical element having a peripheral mounting edge;
and
a retaining ring affixed to the barrel through a set of ring threads complementary to the barrel threads and having a thread angle, the retaining ring comprising an abutment surface engaging the peripheral mounting edge of the optical element along a circular edge contact line, thereby securing the optical element between the seat and the retaining ring, the abutment surface having a frustro-spherical profile having a radius of curvature RRing given by the formula:
R
Ring
=
[
d
ring
2

tan

(
ϕ
threads

/

2
)
-
h
-
T

/

2
]
2
+
Y
2
where:
dring is a diameter of the retaining ring along the ring threads;
ϕthread is a value of the thread angle;
Y is a half-diameter of the peripheral mounting edge;
h is a distance between (i) a first point of contact of the barrel threads with the ring threads proximate to the optical element and (ii) the edge contact line;
and
T is a distance between (i) the first point of contact of the barrel threads with the ring threads proximate to the optical element and (ii) a last point of contact of the barrel threads with the ring threads farthest from the optical element diametrically opposite to the first point of contact.

40 more elements

An optical assembly, comprising:

a barrel having a cavity and a set of barrel threads, the cavity having a longitudinal center axis;
a seat provided in the cavity of the barrel;
an optical element having first surface resting on the seat and a second surface opposite the first surface, said optical element having a peripheral mounting edge along the second surface;
and
a retaining ring affixed to the barrel through a set of ring threads complementary to the barrel threads and having a thread angle, the retaining ring comprising an abutment surface engaging the peripheral mounting edge of the optical element along a circular edge contact line or band, thereby securing the optical element between the seat and the retaining ring, the abutment surface having a frustro-conical profile having an inclination angle α with respect to a plane perpendicular to the longitudinal center axis of the cavity given by the formula:
α
=
sin
-
1
(
Y
[
d
ring
2

tan

(
ϕ
threads

/

2
)
-
h
-
T

/

2
]
2
+
Y
2
)
where:
Y is a half-diameter of the peripheral mounting edge;
dring is a diameter of the retaining ring along the ring threads;
ϕthread is a value of the thread angle;
h is a distance between (i) a first point of contact of the barrel threads with the ring threads proximate to the optical element and (ii) the edge contact line;
and
T is a distance between (i) the first point of contact of the barrel threads with the ring threads proximate to the optical element and (ii) a last point of contact of the barrel threads with the ring threads farthest from the optical element diametrically opposite to the first point of contact.

45 more elements

Dependencies are inferred from the claim text.