Confocal measuring device

• US 10,247,602 B2
• Filed: 12/19/2017
• Issued: 04/02/2019
• Est. Priority Date: 03/09/2017
• Status: Active Grant

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Marukawa, Mariko, Hayakawa, Masayuki, Okuda, Takahiro, Morino, Hisayasu
• Primary Examiner(s): Pham, Hoa Q
• Application Number:
  US15/846,205
• Publication Number:
  US 20180259390A1
• Time in Patent Office: 469 Days
• Field of Search: 356328, 356330, 356305, 359389, 359742, 36911212, 36911223
• CPC Class Codes: G01B 11/026 by measuring distance between sensor and object G01B11/0608 takes precedence
• CPC Class Codes: G01B 2210/50 Using chromatic effects to achieve wavelength-dependent depth resolution
• CPC Class Codes: G01J 1/0411 using focussing or collimating elements, i.e. lenses or mirrors; Aberration correction
• CPC Class Codes: G01J 1/4257 applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam monitoring arrangements for lasers in general H01S3/0014
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/18 using diffraction elements, e.g. grating gratings per se G02B
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08

Abstract

A confocal measuring device capable of enlarging a measurement range using a compact device configuration is provided. A confocal measuring device (1A) is configured to include: a diffractive lens (11) that causes chromatic aberration in light emitted from a white LED light source (21); a diffractive lens (13b) that increases chromatic aberration of light passing through the diffractive lens (11); and an objective lens (12) that condenses light into a measurement target range such that the condensed light has chromatic aberration along an optical axis.

Claims

1. A confocal measuring device using a confocal optical system, the confocal measuring device comprising:

a light source that emits light having a plurality of wavelengths;

a first diffractive lens that causes chromatic aberration in the light emitted from the light source;

a second diffractive lens that increases chromatic aberration of light passing through the first diffractive lens;

an objective lens that condenses light passing through the second diffractive lens into a measurement target range along an optical axis such that the condensed light has chromatic aberration along the optical axis;

a measurement part that measures strength of light of a wavelength focused on a measurement target object among light condensed by the objective lens; and

a first divergence optical part at an objective lens side of the first diffractive lens for diverging light.

2. The confocal measuring device according to claim 1, wherein light incident on the objective lens is collimated.

3. The confocal measuring device according to claim 2, wherein the first divergence optical part is at a light source side of the objective lens for diverging light.

4. The confocal measuring device according to claim 3, wherein the first divergence optical part includes at least one concave lens.

5. The confocal measuring device according to claim 4, wherein, when a focal distance of a divergence system is represented as a negative value, a focal distance of the second diffractive lens f1, a focal distance of the first divergence optical part f2, and a distance between the second diffractive lens and the first divergence optical part d satisfies

f1+f2=d.

6. The confocal measuring device according to claim 5,

wherein the first divergence optical part is arranged between the first diffractive lens and the second diffractive lens, and

wherein light is collimated between the second diffractive lens and the objective lens.

7. The confocal measuring device according to claim 3, wherein, when a focal distance of a divergence system is represented as a negative value, a focal distance of the second diffractive lens f1, a focal distance of the first divergence optical part f2, and a distance between the second diffractive lens and the first divergence optical part d satisfies

f1+f2=d.

8. The confocal measuring device according to claim 7,

wherein the first divergence optical part is arranged between the first diffractive lens and the second diffractive lens, and

wherein light is collimated between the second diffractive lens and the objective lens.

9. The confocal measuring device according to claim 3,

wherein the first divergence optical part is arranged between the first diffractive lens and the second diffractive lens, and

wherein light is collimated between the second diffractive lens and the objective lens.

10. The confocal measuring device according to claim 1, wherein the first divergence optical part is at a light source side of the objective lens for diverging light.

11. The confocal measuring device according to claim 10, wherein the first divergence optical part includes at least one concave lens.

12. The confocal measuring device according to claim 11, wherein, when a focal distance of a divergence system is represented as a negative value, a focal distance of the second diffractive lens f1, a focal distance of the first divergence optical part f2, and a distance between the second diffractive lens and the first divergence optical part d satisfies

f1+f2=d.

13. The confocal measuring device according to claim 12,

wherein the first divergence optical part is arranged between the first diffractive lens and the second diffractive lens, and

wherein light is collimated between the second diffractive lens and the objective lens.

14. The confocal measuring device according to claim 11, further comprising a third diffractive lens that increases chromatic aberration of light and a second divergence optical part that causes light to diverge provided between the first diffractive lens and the objective lens.

15. The confocal measuring device according to claim 10, wherein, when a focal distance of a divergence system is represented as a negative value, a focal distance of the second diffractive lens f1, a focal distance of the first divergence optical part f2, and a distance between the second diffractive lens and the first divergence optical part d satisfies

f1+f2=d.

16. The confocal measuring device according to claim 15,

wherein the first divergence optical part is arranged between the first diffractive lens and the second diffractive lens, and

wherein light is collimated between the second diffractive lens and the objective lens.

17. The confocal measuring device according to claim 10,

wherein the first divergence optical part is arranged between the first diffractive lens and the second diffractive lens, and

wherein light is collimated between the second diffractive lens and the objective lens.

18. The confocal measuring device according to claim 10, further comprising a third diffractive lens that increases chromatic aberration of light and a second divergence optical part that causes light to diverge provided between the first diffractive lens and the objective lens.

19. The confocal measuring device according to claim 1, wherein the focal distance of the first diffractive lens and the focal distance of the second diffractive lens are the same.

20. The confocal measuring device according to claim 1, wherein the focal distance of the first diffractive lens and the focal distance of the second diffractive lens are different from each other.