Birefringence measurement optical system and high spatial resolution polarimetric apparatus

• US 6,157,448 A
• Filed: 10/08/1999
• Issued: 12/05/2000
• Est. Priority Date: 10/08/1999
• Status: Expired due to Fees

• Current Assignee: Uniopt Co., Ltd.
• Original Assignee: Uniopt Co., Ltd.
• Inventors: Kowa, Hiroyuki, Umeda, Norihiro, Mochiduki, Shinji
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Punnoose, Roy M.
• Application Number:
  US09/414,841
• Time in Patent Office: 424 Days
• Field of Search: 356/365, 356/366, 356/367, 356/368, 356/364
• US Class Current: 356/365
• CPC Class Codes: G01J 4/00 Measuring polarisation of light
• CPC Class Codes: G01N 21/23 Bi-refringence

Abstract

The object of the present invention is to measure the amount of birefringence of a target while enhancing spatial resolution. A birefringence measurement optical system is comprised of a Stabilized Transverse Zeeman Laser emitting laser beam in a predetermined polarization state toward a target, a halfwave plate (polarized light emission optical system), a linear polarizer (polarized light detection optical system) detecting information on the retardation, main axial direction and optical rotation angle of the target as a light signal which can be polarimetrically analyzed through the target, and a photo detector converting the light signal from the linear polarizer into an electric signal and detecting the electric signal. An optical fiber (light transmission path) taking out part of light fluxes of the light signal and optically transmitting the part of the light fluxes from the target toward the photo detector, is arranged between the photo detector and the target.

Claims

1. A birefringence measurement optical system comprising:

a polarized light emission optical system emitting a light signal in a predetermined polarization state toward a target to be measured;

a polarized light detection optical system detecting the light signal from the polarized light emission optical system through the target, the light signal including birefringence information on the target which can be polarimetrically analyzed;

a photo detector converting the light signal from the polarized light detection optical system into an electric signal and detecting the electric signal; and

a light transmission path arranged between the target and the photo detector, the light transmission path taking part of light fluxes of the light signal along an axial direction of the light signal from the target at a target side thereof and transmitting the part of light fluxes from the target side toward a photo detector side thereof, the photo detector receiving the part of light fluxes including the birefringence information, which is higher in spatial resolution than all of the light fluxes. for the birefringence measurement of the target.

2. The birefringence measurement optical system according to claim 1, wherein the light transmission path is an optical fiber having an aperture taking the part of light fluxes at the target side.

3. The birefringence measurement optical system according to claim 2, wherein the optical fiber is arranged between the polarized light detection optical system and the photo detector.

4. The birefringence measurement optical system according to claim 2, wherein the optical fiber has a core constituted by material having a predetermined photoelastic constant.

5. The birefringence measurement optical system according to claim 4, wherein the optical fiber is arranged between the target and the polarized light detection optical system.

6. The birefringence measurement optical system according to claim 2, wherein the optical fiber has a sharpened tip end portion directed toward the target at the target side thereof.

7. The birefringence measurement optical system according to claim 2, wherein the optical fiber is integrally attached to at least part of the polarized light detection optical system.

8. The birefringence measurement optical system according to claim 2, further comprising a mechanism for freely scanning at least a target-side tip end portion of the optical fiber within the light fluxes of the light signal.

9. The birefringence measurement optical system according to claim 2, wherein the optical fiber is a plurality of optical fibers and the plurality of optical fibers are arranged in parallel.

10. A high spatial resolution polarimetric apparatus comprising:

a birefringence measurement optical system for measuring birefringence information of a target to be measured; and

analyzing means for analyzing at least one of a retardation, an azimuth angle of a principal axis and an optical rotation angle of the target based on the birefringence Information measured by the birefringence measurement optical system,

wherein the birefringence measurement optical system includes;

a polarized light emission optical system emitting a light signal in a predetermined polarization state toward the target;

a polarized light detection optical system detecting the light signal from the polarized light emission optical system through the target, the light signal including birefringence information on the target which can be polarimetrically analyzed;

a photo detector converting the light signal from the polarized light detection optical system into an electric signal and detecting the electric signal; and

a light transmission path arranged between the target and the photo detector, the light transmission path taking part of light fluxes of the light signal along an axial direction of the light signal from the target at a target side thereof and transmitting the part of light fluxes from the target side toward a photo detector side thereof, the photo detector receiving the part of light fluxes including the birefringence information, which is higher in spatial resolution than all of the light fluxes, for the birefringence measurement of the target.

11. The high spatial resolution polarimetric apparatus according to claim 10, wherein the light transmission path is an optical fiber having an aperture taking the part of light fluxes at the target side.

12. The high spatial resolution polarimetric apparatus according to claim 10, wherein the optical fiber is arranged between the polarized light detection optical system and the photo detector.

13. The high spatial resolution polarimetric apparatus according to claim 10, wherein the optical fiber has a core constituted by material having a predetermined photoelastic constant.

14. The high spatial resolution polarimetric apparatus according to claim 13, wherein the optical fiber is arranged between the target and the polarized light detection optical system.

15. The high spatial resolution polarimetric apparatus according to claim 10, wherein the optical fiber has a sharpened tip end portion directed toward the target at the target side thereof.

16. The high spatial resolution polarimetric apparatus according to claim 10, wherein the optical fiber is integrally attached to at least part of the polarized light detection optical system.

17. The high spatial resolution polarimetric apparatus according to claim 10, further comprising a mechanism for freely scanning at least a target side tip end portion of the optical fiber within the light fluxes of the light signal.

18. The high spatial resolution polarimetric apparatus according to claim 10, wherein the optical fiber is a plurality of optical fibers and the plurality of optical fibers are arranged in parallel.