Faraday rotator device

Patent metadata

Field	Value
Publication number	US-10126172-B1
Application number	US-201715784309-A
Country	US
Kind code	B1
Filing date	Oct 16, 2017
Priority date	Oct 16, 2017
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

A Faraday rotation device includes a light source configured to transmit a light beam; a first rotation stage polarizer configured to forward the light beam from the light source at a predetermined reference polarization angle; a quartz cell configured to receive the light beam from the first rotation stage polarizer at the predetermined reference polarization angle; one or more stacked ring permanent magnets coaxially fitted around the quartz cell; a stepper motor configured to adjust a rotational motion of a second rotation stage polarizer connected to the stepper motor, wherein the second rotation stage polarizer is configured to change a polarization angle of the light beam received from the quartz cell; a light detector; and an electronic circuit board configured to record a change in angle between the predetermined reference polarization angle and the changed polarization angle.

First claim

The invention claimed is:

1. A Faraday rotation device, comprising:
a light source configured to transmit a light beam;
a first rotation stage polarizer configured to forward the light beam from the light source at a predetermined reference polarization angle;
a quartz cell configured to receive the light beam from the first rotation stage polarizer at the predetermined reference polarization angle, the quartz cell including a first hole on a circular entrance of the quartz cell and a second hole on a circular exit of the quartz cell, the first hole and the second hole creating a tunnel within the quartz cell structure and being connectable to a dry vacuum pump to evacuate air, and to flush and change a sample;
one or more stacked ring permanent magnets coaxially fitted around the quartz cell, the one or more stacked ring permanent magnets configured to create a magnetic field encircling the quartz cell and rotate the light beam;
a stepper motor configured to adjust a rotational motion of a second rotation stage polarizer connected to the stepper motor, wherein the second rotation stage polarizer is configured to change a polarization angle of the light beam received from the quartz cell;
a light detector configured to detect the rotated light beam; and
an electronic circuit board configured with circuitry to control the light source, the light detector, and the stepper motor, and to record a change in angle between the predetermined reference polarization angle and the changed polarization angle.

2. The Faraday rotation device of claim 1 , further comprising:
an iris diaphragm configured to collimate the light beam outputted from the light source.

3. The Faraday rotation device of claim 1 , further comprising:
an aspheric lens configured to focus the light beam outputted from the light source.

4. The Faraday rotation device of claim 1 , wherein the light source comprises a light-emitting diode (LED).

5. The Faraday rotation device of claim 4 , wherein the LED is configured to operate within a wavelength range of 400-480 nm.

6. The Faraday rotation device of claim 1 , wherein the light detector comprises a silicon photodiode.

7. The Faraday rotation device of claim 1 , wherein the one or more stacked ring permanent magnets are configured to produce a magnetic field inside the quartz cell parallel to the transmitted light beam from the light source.

8. The Faraday rotation device of claim 1 , wherein the stepper motor is a two-stage stepper motor.

9. The Faraday rotation device according to claim 1 , further comprising a dry vacuum pump configured to connect to at least one of the first hole and the second hole, and provide suction for evacuating air and flushing and changing the sample within the quartz cell.

10. A method of recording a Faraday rotation angle, the method comprising:
transmitting a light beam from a light source through a first rotation stage polarizer at a predetermined reference angle to obtain a first polarization light beam;
transmitting the first polarization light beam through a quartz cell surrounded by one or more stacked ring permanent magnets, the quartz cell including a first hole on a circular entrance of the quartz cell and a second hole on a circular exit of the quartz cell, the first hole and the second hole creating a tunnel within the quartz cell structure and being connectable to a dry vacuum pump to evacuate air, and to flush and change a sample;
rotating, via the one or more stacked ring permanent magnets, a polarization direction of the transmitted first polarization light beam by a predetermined rotation angle;
rotating a second rotation stage polarizer, via a stepper;
receiving the first polarization light beam at the second rotation stage polarizer;
searching, via a photodetector, for a minimal signal from a second polarization light beam emitted from the second rotation stage polarizer;
halting a rotation of the stepper when the minimal signal is detected; and
recording, via an electronic circuit board, a rotation angle between the predetermined reference angle and an angle at which the rotation of the stepper halted.

11. The method of claim 10 , further comprising:
collimating, via an iris diaphragm, the light beam outputted from the light source.

12. The method of claim 10 , further comprising:
focusing, via an aspheric lens, the light beam outputted from the light source.

13. The method of claim 10 , further comprising:
producing, via the one or more stacked ring permanent magnets, a magnetic field inside the quartz cell parallel to the transmitted light beam from the light source.

14. A Faraday rotation device, comprising:
a light source configured to transmit a light beam;
a first rotation stage polarizer configured to forward the light beam from the light source at a predetermined reference polarization angle;
a quartz cell configured to receive the light beam from the first rotation stage polarizer at the predetermined reference polarization angle, the quartz cell including a first hole on a circular entrance of the quartz cell and a second hole on a circular exit of the quartz cell, the first hole and the second hole creating a tunnel within the quartz cell structure and being connectable to a dry vacuum pump to evacuate air, and to flush and change a sample;
one or more stacked ring permanent magnets coaxially fitted around the quartz cell, the one or more stacked ring permanent magnets configured to create a magnetic field encircling the quartz cell and rotate the light beam;
a stepper motor connected to a second rotation stage polarizer, wherein the second rotation stage polarizer is configured to change a polarization angle of the light beam received from the quartz cell;
a light detector configured to detect the rotated light beam; and
processing circuitry configured to
transmit the light beam from the light source through the first rotation stage polarizer to obtain a first polarization light beam;
transmit the first polarization light beam through the quartz cell;
rotate the second rotation stage polarizer, via the stepper;
search for a minimal signal from a second polarization light beam emitted from the second rotation stage polarizer;
halt a rotation of the stepper when the minimal signal is detected; and
record a rotation angle between the predetermined reference angle and an angle at which the rotation of the stepper halted.

15. The Faraday rotation device of claim 14 , wherein the light source comprises a light-emitting diode (LED).

16. The Faraday rotation device of claim 15 , wherein the LED is configured to operate within a wavelength range of 400-480 nm.

17. The Faraday rotation device of claim 14 , wherein the light detector comprises a silicon photodiode.

18. The Faraday rotation device of claim 14 , wherein the stepper motor is a two-stage stepper motor.

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Al-Basheer Watheq
• ABDELAZEM Sohaib

Classifications

• F21V23/003

  the elements being electronics drivers or controllers for operating the light source, e.g. for a LED array · CPC title

• G01J4/04 Primary

  Polarimeters using electric detection means (G01J4/02 takes precedence) · CPC title

• F21Y2115/10

  Light-emitting diodes [LED] · CPC title