Telecentric optical apparatus

Patent metadata

Field	Value
Publication number	US-11467384-B2
Application number	US-201916679731-A
Country	US
Kind code	B2
Filing date	Nov 11, 2019
Priority date	May 28, 2015
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

A telecentric optical apparatus that is capable of suppressing an increase in the number of components as well as achieving high precision optical axis alignment, is provided. The telecentric optical apparatus of the present invention is characterized in that it is provided with: a first telecentric lens surface that is provided on an object side; a second telecentric lens surface that is provided on an image side and that shares a focus position with the first telecentric lens surface; and an optical path trimming part that is provided, between the first telecentric lens surface and the second telecentric lens surface, in an outside region, which is located on a side further out than a light passing region having a center thereof located at the focus position, and that changes an optical path such that a light beam incident on the outside region is prevented from contributing to image formation.

First claim

What is claimed is:

1. A telecentric optical apparatus comprising:
a front-stage lens comprising a first surface on an object side and a second surface on an image side, the first surface being a first telecentric lens surface; and
a rear-stage lens comprising a first surface on the object side and a second surface on the image side, the second surface being a second telecentric lens surface that shares a focus position with the first telecentric lens surface,
wherein at least one of the second surface of the front-stage lens or the first surface of the rear-stage lens is an optical path trimming part that is provided, between the first telecentric lens surface and the second telecentric lens surface, in an outside region, which is located on a side further out than a light passing region having a center thereof located at the focus position, and that changes an optical path such that a light beam incident on the outside region is prevented from contributing to image formation,
wherein no aperture stop is provided between the front-stage lens and the rear-stage lens, and
wherein a clearance gap is provided between the front-stage lens and the rear-stage lens in the light passing region.

2. The telecentric optical apparatus according to claim 1 , wherein the optical path trimming part includes a refractive surface that refracts the optical path to the outside.

3. The telecentric optical apparatus according to claim 2 , wherein the refractive surface includes a lens curved surface.

4. The telecentric optical apparatus according to claim 1 , wherein the optical path trimming part includes a roughened surface that diffuses a light beam incident on the outside region.

5. The telecentric optical apparatus according to claim 1 , wherein
an intermediate region is provided between the front-stage lens and the rear-stage lens, and
the optical path trimming part refracts the optical path depending on a difference between a refractive index of a region that configures the front-stage lens or the rear-stage lens and a refractive index of the intermediate region.

6. The telecentric optical apparatus according to claim 5 , wherein a light transmissibility of the intermediate region is lower than a light transmissibility of the region that configures the front-stage lens or the rear-stage lens.

7. The telecentric optical apparatus according to claim 1 , further comprising a positioning mechanism that includes a reference hole provided in the respective outside regions of the front-stage lens and the rear-stage lens, wherein positioning of the front-stage lens and the rear-stage lens in an optical axis direction and a direction orthogonal to the optical axis direction is achieved by means of the positioning mechanism.

8. The telecentric optical apparatus according to claim 1 , wherein the telecentric optical apparatus does not comprise an aperture stop.

9. The telecentric optical apparatus according to claim 1 , wherein the front-stage lens is not in contact with the rear-stage lens in the light passing region.

10. The telecentric optical apparatus according to claim 1 , further comprising a positioning mechanism for positioning the front-stage lens and the rear-stage lens in an optical axis direction and a direction orthogonal to the optical axis direction,
wherein the positioning mechanism comprises:
a first reference hole in the front-stage lens on a side further out than the outside region;
a second reference hole in the rear-stage lens on a side further out than the outside region; and
a reference rod inserted in the first reference hole and the second reference hole.

11. The telecentric optical apparatus according to claim 10 , wherein the reference rod includes a part having a diameter larger than the diameters of the first reference hole and the second reference hole, the part being provided between the front-stage lens and the rear-stage lens, and
a thickness of the part of the reference rod is determined in such a manner that the focus positions of the front-stage lens and the rear-stage lens coincide with each other.

Assignees

• Mitutoyo Corp

Inventors

• Okabe Kenji
• Nagahama Tatsuya
• Yaku Toru
• Ono Kimitoshi

Classifications

• G02B13/22 Primary

  Telecentric objectives or lens systems · CPC title

• G02B3/00

  Simple or compound lenses · CPC title

• G02B7/021

  for more than one lens · CPC title

• G02B5/005

  Diaphragms (for cameras G03B9/02) · CPC title

• G02B5/021

  the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures · CPC title