CA2278981A1 - Ellipsometer - Google Patents
Ellipsometer Download PDFInfo
- Publication number
- CA2278981A1 CA2278981A1 CA 2278981 CA2278981A CA2278981A1 CA 2278981 A1 CA2278981 A1 CA 2278981A1 CA 2278981 CA2278981 CA 2278981 CA 2278981 A CA2278981 A CA 2278981A CA 2278981 A1 CA2278981 A1 CA 2278981A1
- Authority
- CA
- Canada
- Prior art keywords
- polarizers
- polarization state
- photodetectors
- light
- waveplates
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000010287 polarization Effects 0.000 claims abstract description 16
- 230000005540 biological transmission Effects 0.000 claims description 6
- 230000010363 phase shift Effects 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 5
- 238000000034 method Methods 0.000 abstract 1
- 241001416181 Axis axis Species 0.000 description 1
- 241000030560 Styx Species 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J4/00—Measuring polarisation of light
- G01J4/04—Polarimeters using electric detection means
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Field of the invention Present invention relates to an ellipsometer, a device which senses the polarization state of monochromatic light. The device measures all the parameters of the polarization state of light: the degree-of-polarization, azimuth angle and ellipticity. Since there are no moving parts, the measurement is faster and it is much lower in cost.
Therefore, this type of ellipsometer can be used for popular applications.
Description of the prior art There are many optic solutions for sensing the polarization state of light.
All of them utilize one or more polarizers , one or more waveplates and one or more photodetectors. To obtain the three parameters describing the polarization state of monochromatic light, a set of measurements has to be taken from different positions of the polarizers, waveplates or photodetectors. Therefore, data acquisition time depends on how fast the polarizers, waveplates or photodetectors are moved to their various measurement positions.
In addition, the precision of positioning the polarizers, waveplates or photodetectors influences the result of the measurement. This method of obtaining the polarization state of monochromatic light limits the use to non popular applications and needs skilled personnel to handle it.
Therefore, this type of ellipsometer can be used for popular applications.
Description of the prior art There are many optic solutions for sensing the polarization state of light.
All of them utilize one or more polarizers , one or more waveplates and one or more photodetectors. To obtain the three parameters describing the polarization state of monochromatic light, a set of measurements has to be taken from different positions of the polarizers, waveplates or photodetectors. Therefore, data acquisition time depends on how fast the polarizers, waveplates or photodetectors are moved to their various measurement positions.
In addition, the precision of positioning the polarizers, waveplates or photodetectors influences the result of the measurement. This method of obtaining the polarization state of monochromatic light limits the use to non popular applications and needs skilled personnel to handle it.
Description
SPECIFICATIONS
SUMMARY OF THE INVENTION
An array of six or more photodetectors is covered by a special analyzing mask.
The mask consists of four or more polarizers in different positions covering six or more photodetectors and a waveplate covering two or more photodetectors. The described configuration is ideal for obtaining the polarization state of monochromatic light. However other configurations can be used to the same effect. The electric signals from the photodetectors are used in conjunction with a computer to produce information about the polarization state of monochromatic light. Assuming that the change of the polarization state of light on the photodetector array's aperture is negligible and the size of each photodetector is small, the distance between the photodetectors does not affect the measurement accuracy.
5536 Regional Road #81, BEAMSVILLE, ON LOR 1B3 CANADA
email:hohner cLDhohner.com web:www.hohner.com HOhller COrp. Tel (905) 563 4924 Fax (905) 563 7209 Toll Free 1-800-295-5693 All signals from the photodetector array are processed using a signal conditioner and a computer. The computer calculates all the parameters completely describing the polarization state of monochromatic light, such as the degree-of-polarization, azimuth angle and ellipticity.
The following example describes an ellipsometer with six photodetectors, four polarizers and one waveplate.
Detectors XX, YY, XY, YX are covered by polarizers only. Detectors iXY and iYX
are covered by polarizers and a waveplate having the phase shift between its "slov~' and "fast" axes equal to ~°.
Below is a table showing the angle position of the analyzing elements in the analyzing mask regarding the device's coordinate axis X.
PhotodetectorSignal produced Angle between the Angle between the "fast' designation by transmission axis axis of the waveplate the photodetectorof and polarizers and the the device's coordinate device's axis coordinate axis X X
Sxx -YY S 90, -XY Sx 45 :,; -YX S x 135 -Stx 45 0 '~ St x 135 0 With the six signals from the photodetectors, the parameters S~, SZ and S3 of the normalized Stokes vector S can be calculated using the following equations:
S = S.~ _ Sn.
' S"x + Sri Sz=Sxr_S~
5,~, + S~
5;~, - S~
-SZCosrp S;,n, + S~
Sin y~
SUMMARY OF THE INVENTION
An array of six or more photodetectors is covered by a special analyzing mask.
The mask consists of four or more polarizers in different positions covering six or more photodetectors and a waveplate covering two or more photodetectors. The described configuration is ideal for obtaining the polarization state of monochromatic light. However other configurations can be used to the same effect. The electric signals from the photodetectors are used in conjunction with a computer to produce information about the polarization state of monochromatic light. Assuming that the change of the polarization state of light on the photodetector array's aperture is negligible and the size of each photodetector is small, the distance between the photodetectors does not affect the measurement accuracy.
5536 Regional Road #81, BEAMSVILLE, ON LOR 1B3 CANADA
email:hohner cLDhohner.com web:www.hohner.com HOhller COrp. Tel (905) 563 4924 Fax (905) 563 7209 Toll Free 1-800-295-5693 All signals from the photodetector array are processed using a signal conditioner and a computer. The computer calculates all the parameters completely describing the polarization state of monochromatic light, such as the degree-of-polarization, azimuth angle and ellipticity.
The following example describes an ellipsometer with six photodetectors, four polarizers and one waveplate.
Detectors XX, YY, XY, YX are covered by polarizers only. Detectors iXY and iYX
are covered by polarizers and a waveplate having the phase shift between its "slov~' and "fast" axes equal to ~°.
Below is a table showing the angle position of the analyzing elements in the analyzing mask regarding the device's coordinate axis X.
PhotodetectorSignal produced Angle between the Angle between the "fast' designation by transmission axis axis of the waveplate the photodetectorof and polarizers and the the device's coordinate device's axis coordinate axis X X
Sxx -YY S 90, -XY Sx 45 :,; -YX S x 135 -Stx 45 0 '~ St x 135 0 With the six signals from the photodetectors, the parameters S~, SZ and S3 of the normalized Stokes vector S can be calculated using the following equations:
S = S.~ _ Sn.
' S"x + Sri Sz=Sxr_S~
5,~, + S~
5;~, - S~
-SZCosrp S;,n, + S~
Sin y~
5536 Regional Road #81, BEAMSVILLE, ON LOR 1 B3 CANADA
email:hohner~hohner.com web:www.hohner.com Hohr~er Corp. Tel (905) 563 4924 Fax (905) 563 7209 Toll Free 1-800-295-5693 Having known the parameters S~ , SZ and S3, the polarization parameters are:
- Degree-of-polarization P
P = S; + Si + S3 - Azimuth angle A
A = 1 ArcTan s' 2 Sz - Ellipticity a a = 1 ArcSi S3 2 ~P~
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is the schematic view of the device structure. The view includes the following elements:
1 - A six-element photodetector array 2 - A signal conditioner 3 - A computer Figure 2 shows the position of analyzing elements and photodetectors relatively to the device's coordinate frame.
1 - XX photodetector,produces signal S,~,~
2 - YY photodetector,produces signal Sri 3 - XY photodetector,produces signal Sxy 4 - YX photodetector,produces signal Syx - iXY photodetector,produces signal Sixy 6 - iYX photodetector,produces signal Styx 5536 Regional Road #81, BEAMSVILLE, ON LOR 1 B3 CANADA
email:hohner~hohner.com web:www.hohner.com HOhr~er Corp. Tel (905) 563 4924 Fax (905) 563 7209 TOII Free 1-800-295-5693 7 - XX polarizer 8 - YY polarizer 9 - XY polarizes - YX polarizes 11 - a waveplate, has the phase shift equal to ~ degrees with between "slow"
and "fast"
axis.
12 - device's coordinate axis X
5536 Regional Road #81, BEAMSVILLE, ON LOR 1 B3 CANADA
email:hohner~hohner.com web:www.hohner.com Hohner Corp. Tel (905) 563 4924 Fax (905) 563 7209 TOII Free 1-800-295-5693 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The operational principle of the device representing the invention is described with reference to Figure 1. , Each element of a six-element photodetector array 1 is connected to a signal conditioner 2. The signal conditioner 2 transfers the signals from the six-element photodetector array 1 into a computer 3. Computer 3 acquires value of the signal of each photodetector simultaneously and calculates all parameters of the polarization state of monochromatic light.
The principle of getting the polarization parameters is described with reference to Figure 2.
Normalized Stokes vector S is used as a primary information about the polarization state of monochromatic' light.
The XX-photodetector 1 is covered by the XX-polarizer 7. The YY-photodetector 2 is covered by the YY-polarizer 8. The XY photodetector 3 is covered by the XY-polarizer 9.
The YX-photodetector 4 is covered by the YX-polarizer 10. The iXY-photodetector 5 is covered by the XY-polarizer 9 and the waveplate 11. The iYX-photodetector 6 is covered by the YX-polarizer 10 and the waveplate 11.
The transmission axis of the XX-polarizer 7 is parallel to the device's coordinate axis X 12. The transmission axis of the YY-polarizer 8 is normal to device's coordinate axis X
12. The transmission axis of the XY-polarizer 9 makes 45° angle to the device's coordinate axis X 12. The transmission axis of the XY-polarizer 9 makes 135° angle to the device's coordinate axis X 12. °Fast" axis ~ and °slovW' axis rl of the waveplate 11 are parallel and normal to the device's coordinate axis X 12, respectively.
The equations for normalized Stokes vector S are S =S~-Sri ' S,a + S», SZ - S,n, - S~
email:hohner~hohner.com web:www.hohner.com Hohr~er Corp. Tel (905) 563 4924 Fax (905) 563 7209 Toll Free 1-800-295-5693 Having known the parameters S~ , SZ and S3, the polarization parameters are:
- Degree-of-polarization P
P = S; + Si + S3 - Azimuth angle A
A = 1 ArcTan s' 2 Sz - Ellipticity a a = 1 ArcSi S3 2 ~P~
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is the schematic view of the device structure. The view includes the following elements:
1 - A six-element photodetector array 2 - A signal conditioner 3 - A computer Figure 2 shows the position of analyzing elements and photodetectors relatively to the device's coordinate frame.
1 - XX photodetector,produces signal S,~,~
2 - YY photodetector,produces signal Sri 3 - XY photodetector,produces signal Sxy 4 - YX photodetector,produces signal Syx - iXY photodetector,produces signal Sixy 6 - iYX photodetector,produces signal Styx 5536 Regional Road #81, BEAMSVILLE, ON LOR 1 B3 CANADA
email:hohner~hohner.com web:www.hohner.com HOhr~er Corp. Tel (905) 563 4924 Fax (905) 563 7209 TOII Free 1-800-295-5693 7 - XX polarizer 8 - YY polarizer 9 - XY polarizes - YX polarizes 11 - a waveplate, has the phase shift equal to ~ degrees with between "slow"
and "fast"
axis.
12 - device's coordinate axis X
5536 Regional Road #81, BEAMSVILLE, ON LOR 1 B3 CANADA
email:hohner~hohner.com web:www.hohner.com Hohner Corp. Tel (905) 563 4924 Fax (905) 563 7209 TOII Free 1-800-295-5693 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The operational principle of the device representing the invention is described with reference to Figure 1. , Each element of a six-element photodetector array 1 is connected to a signal conditioner 2. The signal conditioner 2 transfers the signals from the six-element photodetector array 1 into a computer 3. Computer 3 acquires value of the signal of each photodetector simultaneously and calculates all parameters of the polarization state of monochromatic light.
The principle of getting the polarization parameters is described with reference to Figure 2.
Normalized Stokes vector S is used as a primary information about the polarization state of monochromatic' light.
The XX-photodetector 1 is covered by the XX-polarizer 7. The YY-photodetector 2 is covered by the YY-polarizer 8. The XY photodetector 3 is covered by the XY-polarizer 9.
The YX-photodetector 4 is covered by the YX-polarizer 10. The iXY-photodetector 5 is covered by the XY-polarizer 9 and the waveplate 11. The iYX-photodetector 6 is covered by the YX-polarizer 10 and the waveplate 11.
The transmission axis of the XX-polarizer 7 is parallel to the device's coordinate axis X 12. The transmission axis of the YY-polarizer 8 is normal to device's coordinate axis X
12. The transmission axis of the XY-polarizer 9 makes 45° angle to the device's coordinate axis X 12. The transmission axis of the XY-polarizer 9 makes 135° angle to the device's coordinate axis X 12. °Fast" axis ~ and °slovW' axis rl of the waveplate 11 are parallel and normal to the device's coordinate axis X 12, respectively.
The equations for normalized Stokes vector S are S =S~-Sri ' S,a + S», SZ - S,n, - S~
5,,9, + S~
5;,~, - S~
- SZCosrp 5;,~, + S~
S3 =
Sin~p 5536 Regional Road #81, BEAMSVILLE, ON LOR 1 B3 CANADA
email:hohner cL'Dhohner.com web:www.hohner.com
5;,~, - S~
- SZCosrp 5;,~, + S~
S3 =
Sin~p 5536 Regional Road #81, BEAMSVILLE, ON LOR 1 B3 CANADA
email:hohner cL'Dhohner.com web:www.hohner.com
Claims (4)
1. An ellipsometer with no moving parts consisting of an analyzing mask, six or more photodetectors followed by a signal conditioner connected to a computer to calculate the polarization state of monochromatic light.
2. An analyzing mask with polarizers and waveplates placed over six or more photodetectors in a way that the polarization state of monochromatic light can be measured.
3. Four polarizers and a waveplate provide six light signals S xx, S yy, S xy, S yx, S ixy, S lyx carrying information about the polarization state of incident light. Signals S
xx, S yy, S xy, S yx are produced using polarizers only. Signals S lxy, S iyx are produced by polarizers and a waveplate having the phase shift ~° between its "slow" and "fast"
axes. The table below shows the angle position of the analyzing elements in the analyzing mask regarding to the device's coordinate axis X.
Light signal Angle between the transmission~ Angle between the "fast" axis of axis of polarizers and the device's the waveplate and the device's coordinate axis X ~ coordinate axis X
S xx 0° -S yy 90° -S xy 45° -S yx 135° -S lxy 45°
0°
S lyx 135°
0°
xx, S yy, S xy, S yx are produced using polarizers only. Signals S lxy, S iyx are produced by polarizers and a waveplate having the phase shift ~° between its "slow" and "fast"
axes. The table below shows the angle position of the analyzing elements in the analyzing mask regarding to the device's coordinate axis X.
Light signal Angle between the transmission~ Angle between the "fast" axis of axis of polarizers and the device's the waveplate and the device's coordinate axis X ~ coordinate axis X
S xx 0° -S yy 90° -S xy 45° -S yx 135° -S lxy 45°
0°
S lyx 135°
0°
4. That with the claims 1, 2 and 3 the parameters S1, S2 and S3 of the normalized Stokes vector S can be calculated using the following equations:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2278981 CA2278981A1 (en) | 1999-07-23 | 1999-07-23 | Ellipsometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2278981 CA2278981A1 (en) | 1999-07-23 | 1999-07-23 | Ellipsometer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2278981A1 true CA2278981A1 (en) | 2001-01-23 |
Family
ID=4163852
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2278981 Abandoned CA2278981A1 (en) | 1999-07-23 | 1999-07-23 | Ellipsometer |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2278981A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2452924C1 (en) * | 2010-12-27 | 2012-06-10 | Геннадий Михайлович Михеев | Method of determining circular polarisation sign of laser radiation |
| US20150219497A1 (en) * | 2014-02-06 | 2015-08-06 | Film Sense, LLC | Multiple Wavelength Ellipsometer System and Related Method |
-
1999
- 1999-07-23 CA CA 2278981 patent/CA2278981A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2452924C1 (en) * | 2010-12-27 | 2012-06-10 | Геннадий Михайлович Михеев | Method of determining circular polarisation sign of laser radiation |
| US20150219497A1 (en) * | 2014-02-06 | 2015-08-06 | Film Sense, LLC | Multiple Wavelength Ellipsometer System and Related Method |
| US9354118B2 (en) * | 2014-02-06 | 2016-05-31 | Film Sense, LLC | Multiple wavelength ellipsometer system and related method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |