Photomagnetic field sensor
A photo magnetic field sensor includes a Faraday rotator made of a paramagnetic material, a polarizer, an analyzer, a light-irradiating element, and a light-sensing element. The Faraday rotator is made of a paramagnetic garnet single crystal including at least Tb and Al.
1. A photo magnetic field sensor comprising:
a Faraday rotator including a paramagnetic material, a polarizer, an analyzer, a light-irradiating element, and a light-sensing element; wherein
the paramagnetic material is made of a paramagnetic garnet single crystal consisting essentially of an oxide of Tb, and Al and at least one of Pr and Ce.
2. A photo magnetic field sensor according to claim 1 , wherein the analyzer is arranged on an emergence side of the Faraday rotator and along an optical axis substantially parallel to the Faraday rotator.
3. A photo magnetic field sensor according to claim 1 , wherein the polarizer is provided on an incidence side of the Faraday rotator.
4. A photo magnetic field sensor according to claim 1 , wherein the polarizer and the analyzer are arranged such that an optical axis extended through the Faraday rotator passes through the polarization planes of the polarizer and the analyzer.
5. A photo magnetic field sensor according to claim 1 , wherein the light-irradiating element is arranged such that light falls on the polarizer.
6. A photo magnetic field sensor according to claim 1 , wherein a first total reflecting mirror is provided between the light-irradiating element and the polarizer.
7. A photo magnetic field sensor according to claim 6 , wherein a second total reflecting mirror is provided between the analyzer and the light-sensing element.
8. A photo magnetic field sensor according to claim 7 , wherein collective lenses are provided between the first total reflecting mirror and the polarizer and between the second total reflecting mirror and the analyzer, respectively.
9. A photo magnetic field sensor comprising:
a Faraday rotator including a paramagnetic material, a polarizer, an analyzer, a light-irradiating element, and a light-sensing element; wherein
the paramagnetic material has a columnar shape in which a diameter A in mm of the column of the Faraday rotator and a distance B in mm between one end of the Faraday rotator and the other end thereof satisfies 0<A≦2 and 1≦B/A≦10; and
the paramagnetic material is made of a paramaganetic single crystal consisting essentially of an oxide of Tb, Al and at least one of Pr and Ce.
10. A photo magnetic field sensor according to claim 9 , wherein the analyzer is arranged on an emergence side of the paramagnetic material and along an optical axis substantially parallel to the paramagnetic material.
11. A photo magnetic field sensor according to claim 9 , wherein the polarizer is provided on an incidence side of the paramagnetic material.
12. A photo magnetic field sensor according to claim 9 , wherein the polarizer and the analyzer are arranged such that an optical axis extended through the Faraday rotator passes through the polarization planes of the polarizer and the analyzer.
13. A photo magnetic field sensor according to claim 9 , wherein the light-irradiating element is arranged such that light falls on the polarizer.
14. A photo magnetic field sensor according to claim 9 , wherein a first total reflecting mirror is provided between the light-irradiating element and the polarizer.
15. A photo magnetic field sensor according to claim 14 , wherein a second total reflecting mirror is provided between the analyzer and the light-sensing element.
16. A photo magnetic field sensor according to claim 15 , wherein collective lenses are provided between the first total reflecting mirror and the polarizer and between the second total reflecting mirror and the analyzer, respectively.