CA2246115A1 - An optical device for roughness measurement - Google Patents
An optical device for roughness measurement Download PDFInfo
- Publication number
- CA2246115A1 CA2246115A1 CA 2246115 CA2246115A CA2246115A1 CA 2246115 A1 CA2246115 A1 CA 2246115A1 CA 2246115 CA2246115 CA 2246115 CA 2246115 A CA2246115 A CA 2246115A CA 2246115 A1 CA2246115 A1 CA 2246115A1
- Authority
- CA
- Canada
- Prior art keywords
- roughness
- light
- interference pattern
- rough surface
- measurement
- 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
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
- G01B11/306—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces for measuring evenness
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
- G01B11/303—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces using photoelectric detection means
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
These present inventions represent optical devices for remote measurement of one-dimension roughness. These devices allow the measurement of the roughness automatically with the use of a computer.
The first method for the measurement:
The interference one-dimension pattern is formed on the rough surface. The direction of a roughness coincides with the direction of the interference pattern. If the bandwidth in the interference pattern is equal to the period of the roughness, then the light reflected from a rough surface has maximum or minimum intensity. By changing bandwidth in interference pattern and synchronously measuring intensity of the light reflected from a rough surface, it is possible to obtain the information about bandwidth in the interference pattern when the signal has a maximum or minimum intensity.
The second method for the measurement:
The light from a point source goes on a rough surface and is reflected by it.
Reflected light has defined distribution depending on the roughness size. To measure the roughness size it is necessary to compare intensities of reflected light in specular direction and any additional direction.
The first method for the measurement:
The interference one-dimension pattern is formed on the rough surface. The direction of a roughness coincides with the direction of the interference pattern. If the bandwidth in the interference pattern is equal to the period of the roughness, then the light reflected from a rough surface has maximum or minimum intensity. By changing bandwidth in interference pattern and synchronously measuring intensity of the light reflected from a rough surface, it is possible to obtain the information about bandwidth in the interference pattern when the signal has a maximum or minimum intensity.
The second method for the measurement:
The light from a point source goes on a rough surface and is reflected by it.
Reflected light has defined distribution depending on the roughness size. To measure the roughness size it is necessary to compare intensities of reflected light in specular direction and any additional direction.
Description
Hohner Corp. Tel (9 5) 563 49245 lFax (905) 563-7209 Toll Free 1-800-295-5693 An Optical Device For Roughness Measurement BACKGROUND OF THE INVENTION
Field of the invention The present invention relates to optical remote devices for measuring one-dimension roughness, which use the effect of light reflection from a surface.
These devices allow the measurements of roughness automatically with the use of a computer.
Description of the prior art There are two basic methods to measure the roughness of a surface, optically and mechanically.
Mechanical methods are based on the principle of profilometers. These are very expensive and unstable devices, the main disadvantage of these devices is the contact with the surface, which could scratch the surface and the device could give inaccurate readings of the roughness measurement.
The present invention consists of two simple principles, which are used to measure roughness. Realization of these methods is inexpensive and do not require any high precision and sophisticated mechanical and optical applications. The use of a computer allows fast and easy measurements. Due to its simplicity, this product can also be used to measure roughness in continuous production processes.
5536 Regional Road #81, BEAMSVILLE, ON LOR 1B3 CANADA
email: hohnerC hohner.com web: www.hohner.com SUMMARY OF THE INVENTIONS
These present inventions represent optical devices for remote measurement of one-dimension roughness. These devices allow the measurement of the roughness automatically with the use of a computer.
The first method for the measurement The interference one-dimension pattern is formed on the rough surface. The direction of a roughness coincides with the direction of the interference pattern. If the bandwidth in the interference pattern is equal to the period of the roughness, then the light reflected from a rough surface has maximum or minimum intensity. By changing bandwidth in interference pattern and synchronously measuring intensity of the light reflected from a rough surface, it is possible to obtain the information about bandwidth in the interference pattern when the signal has a maximum or minimum intensity.
The second method for the measurement The light from a point source goes on a rough surface and is reflected by it.
Reflected light has defined distribution depending on the roughness size. To measure the roughness size it is necessary to compare intensities of reflected light in specular direction and any additional direction.
Field of the invention The present invention relates to optical remote devices for measuring one-dimension roughness, which use the effect of light reflection from a surface.
These devices allow the measurements of roughness automatically with the use of a computer.
Description of the prior art There are two basic methods to measure the roughness of a surface, optically and mechanically.
Mechanical methods are based on the principle of profilometers. These are very expensive and unstable devices, the main disadvantage of these devices is the contact with the surface, which could scratch the surface and the device could give inaccurate readings of the roughness measurement.
The present invention consists of two simple principles, which are used to measure roughness. Realization of these methods is inexpensive and do not require any high precision and sophisticated mechanical and optical applications. The use of a computer allows fast and easy measurements. Due to its simplicity, this product can also be used to measure roughness in continuous production processes.
5536 Regional Road #81, BEAMSVILLE, ON LOR 1B3 CANADA
email: hohnerC hohner.com web: www.hohner.com SUMMARY OF THE INVENTIONS
These present inventions represent optical devices for remote measurement of one-dimension roughness. These devices allow the measurement of the roughness automatically with the use of a computer.
The first method for the measurement The interference one-dimension pattern is formed on the rough surface. The direction of a roughness coincides with the direction of the interference pattern. If the bandwidth in the interference pattern is equal to the period of the roughness, then the light reflected from a rough surface has maximum or minimum intensity. By changing bandwidth in interference pattern and synchronously measuring intensity of the light reflected from a rough surface, it is possible to obtain the information about bandwidth in the interference pattern when the signal has a maximum or minimum intensity.
The second method for the measurement The light from a point source goes on a rough surface and is reflected by it.
Reflected light has defined distribution depending on the roughness size. To measure the roughness size it is necessary to compare intensities of reflected light in specular direction and any additional direction.
Hohner Corp. Tel (905) 563-4924 Fax (905) 563-7209 TOII Free 1-800-295-5693 SPECIFICATIONS
An Optical Device For Roughness Measurement BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is the schematic view of the measurement principle. The view includes the following elements:
1 - light beam # 1 with wavelength ~, 2 - light beam # 2 with wavelength ~, 3 - interference pattern from beam #1 and beam # 2 with bandwidth b 4 - a rough surface with roughness period t - light reflected from a rough surface Figure 2 is the schematic view of a roughness measurement device. The view includes the following elements:
1 - a light source which produces beam with wavelength ~, 2 - a beam splitter which produces two beams from one 3a, 3b - a moving mirrors which set distance D between beams 4 - an objective which focuses two beams into its focus to produce interference pattern 5 - a rough surface with roughness period t 6 - an objective which collects reflected light on photodetector 7 - a photodetector 8 - a computer Figure 3 is the schematic view of the measurement principle. The view includes the following elements:
1 - a point light source 2 - a rough surface 3 - light reflected from a rough surface 4a - specular direction of analysis of the light intensity 4a - additional direction of analysis of the light intensity Figure 4 is the schematic view of a roughness measurement device. The view includes the following elements:
1 - a light source 2 - a rough surface 3a - a photodetector 3b - a photodetector 4 - a computer 5536 Regional Road #81, BEAMSVILLE, ON LOR 1B3 CANADA
email: hohner~hohner.com web: www.hohner.com DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The measurement principle of the present invention will now be described with reference to figure 1.
Beam # 1 and beam # 2 produce the interference pattern 3.
Bandwidth b of the interference pattern depends on the angle between beams E
and the wavelength of light ~,. Interference pattern 3 has the bandwidth b equal to b = , where Sins) s - angle between beams, ~, - wavelength of the radiation.
If the bandwidth b in the interference pattern is equal to the period t of the roughness, then the light reflected from a rough surface 4 has maximum or minimum intensity. By changing bandwidth b in the interference pattern and synchronously collecting signal from a photodetector 7 with the use of a computer 8, it is possible to obtain the information about bandwidth b in the interference pattern when the signal has a maximum or minimum intensity.
Embodiments of the present invention will now be described with reference to figure 2.
The primary beam with wavelength ~, from a light source 1 goes through a beam splitter 2. Beam splitter 2 divides primary beam in two beams, which are in the same plane and have opposite directions. After a beam splitter 2 beams go to moving reflecting surfaces 3a and 3b. Reflecting surfaces 3a and 3b move and change the distance D between beams. Objective 4 focuses beams into its focus so they produce interference pattern. Bandwidth b of the interference pattern depends on the focal length of objective F, the distance between beams D and the light wavelength ~,.
Interference pattern 3 has the bandwidth b equal to b = D , where Sin 2 * ArcTg -F - focal length of objective 4, D - distance between beams, ~, - wavelength of the radiation.
Rough surtace 5 is placed into the interterence pattern. Direction of a roughness coincides to the direction of the interference pattern. An objective 6 and an objective 4 collect light reflected from a rough surface 5 to a photodetector 7. Signal from photodetector 7 goes to a computer 8. Computer 8 collects signal data during measurement and finds the roughness of surtace 5.
The measurement principle of the present invention will now be described with reference to figure 3.
Light from point source 1 is reflected from rough surtace 2. Spatial distribution of the light reflected from rough surtace 2 depends on the roughness size. If a surtace 2 is not rough, the light intensity in specular direction 4a is maximum and the light intensity in any additional direction 4b is zero. If a surtace 2 is absolutely rough, then light intensities in both direction 4a and direction 4b are equal to each other. To obtain size of a roughness it is necessary to compare intensities of reflected light in specular direction 4a and in any additional direction 4b.
Embodiments of the present invention will now be described with reference to figure 4.
Light from a source 1 goes on a rough surtace 2. Rough surface 2 reflects incident light. Photodetector 3a is placed in specular direction of reflectance.
Photodetector 3b is placed in additional direction. Computer 5 compares signals from photodetectors 3a and 3b calculates the size of a roughness.
An Optical Device For Roughness Measurement BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is the schematic view of the measurement principle. The view includes the following elements:
1 - light beam # 1 with wavelength ~, 2 - light beam # 2 with wavelength ~, 3 - interference pattern from beam #1 and beam # 2 with bandwidth b 4 - a rough surface with roughness period t - light reflected from a rough surface Figure 2 is the schematic view of a roughness measurement device. The view includes the following elements:
1 - a light source which produces beam with wavelength ~, 2 - a beam splitter which produces two beams from one 3a, 3b - a moving mirrors which set distance D between beams 4 - an objective which focuses two beams into its focus to produce interference pattern 5 - a rough surface with roughness period t 6 - an objective which collects reflected light on photodetector 7 - a photodetector 8 - a computer Figure 3 is the schematic view of the measurement principle. The view includes the following elements:
1 - a point light source 2 - a rough surface 3 - light reflected from a rough surface 4a - specular direction of analysis of the light intensity 4a - additional direction of analysis of the light intensity Figure 4 is the schematic view of a roughness measurement device. The view includes the following elements:
1 - a light source 2 - a rough surface 3a - a photodetector 3b - a photodetector 4 - a computer 5536 Regional Road #81, BEAMSVILLE, ON LOR 1B3 CANADA
email: hohner~hohner.com web: www.hohner.com DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The measurement principle of the present invention will now be described with reference to figure 1.
Beam # 1 and beam # 2 produce the interference pattern 3.
Bandwidth b of the interference pattern depends on the angle between beams E
and the wavelength of light ~,. Interference pattern 3 has the bandwidth b equal to b = , where Sins) s - angle between beams, ~, - wavelength of the radiation.
If the bandwidth b in the interference pattern is equal to the period t of the roughness, then the light reflected from a rough surface 4 has maximum or minimum intensity. By changing bandwidth b in the interference pattern and synchronously collecting signal from a photodetector 7 with the use of a computer 8, it is possible to obtain the information about bandwidth b in the interference pattern when the signal has a maximum or minimum intensity.
Embodiments of the present invention will now be described with reference to figure 2.
The primary beam with wavelength ~, from a light source 1 goes through a beam splitter 2. Beam splitter 2 divides primary beam in two beams, which are in the same plane and have opposite directions. After a beam splitter 2 beams go to moving reflecting surfaces 3a and 3b. Reflecting surfaces 3a and 3b move and change the distance D between beams. Objective 4 focuses beams into its focus so they produce interference pattern. Bandwidth b of the interference pattern depends on the focal length of objective F, the distance between beams D and the light wavelength ~,.
Interference pattern 3 has the bandwidth b equal to b = D , where Sin 2 * ArcTg -F - focal length of objective 4, D - distance between beams, ~, - wavelength of the radiation.
Rough surtace 5 is placed into the interterence pattern. Direction of a roughness coincides to the direction of the interference pattern. An objective 6 and an objective 4 collect light reflected from a rough surface 5 to a photodetector 7. Signal from photodetector 7 goes to a computer 8. Computer 8 collects signal data during measurement and finds the roughness of surtace 5.
The measurement principle of the present invention will now be described with reference to figure 3.
Light from point source 1 is reflected from rough surtace 2. Spatial distribution of the light reflected from rough surtace 2 depends on the roughness size. If a surtace 2 is not rough, the light intensity in specular direction 4a is maximum and the light intensity in any additional direction 4b is zero. If a surtace 2 is absolutely rough, then light intensities in both direction 4a and direction 4b are equal to each other. To obtain size of a roughness it is necessary to compare intensities of reflected light in specular direction 4a and in any additional direction 4b.
Embodiments of the present invention will now be described with reference to figure 4.
Light from a source 1 goes on a rough surtace 2. Rough surface 2 reflects incident light. Photodetector 3a is placed in specular direction of reflectance.
Photodetector 3b is placed in additional direction. Computer 5 compares signals from photodetectors 3a and 3b calculates the size of a roughness.
Claims
1 - One-dimension roughness can be measured using a one-dimension interference pattern, when the bandwidth of an interference pattern is equal to the period of a roughness. If the bandwidth of an interference pattern is equal to the period of a roughness, then light reflected from a rough surface has maximum or minimum intensity.
3 - One-dimension roughness can be measured by comparing intensity of specular reflectance with intensity of light reflected in any additional direction.
3 - One-dimension roughness can be measured by comparing intensity of specular reflectance with intensity of light reflected in any additional direction.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2246115 CA2246115A1 (en) | 1998-09-15 | 1998-09-15 | An optical device for roughness measurement |
| GB9902029A GB2346440A (en) | 1998-09-15 | 1999-02-01 | Optical device for roughness measurement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2246115 CA2246115A1 (en) | 1998-09-15 | 1998-09-15 | An optical device for roughness measurement |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2246115A1 true CA2246115A1 (en) | 2000-03-15 |
Family
ID=4162784
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2246115 Abandoned CA2246115A1 (en) | 1998-09-15 | 1998-09-15 | An optical device for roughness measurement |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2246115A1 (en) |
| GB (1) | GB2346440A (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3804521A (en) * | 1972-02-22 | 1974-04-16 | Itek Corp | Optical device for measuring surface roughness |
| US4334780A (en) * | 1979-06-29 | 1982-06-15 | Grumman Aerospace Corporation | Optical surface roughness detection method and apparatus |
| DE19733775A1 (en) * | 1997-08-05 | 1999-02-18 | Honeywell Ag | Measuring surface roughness of reflective material, e.g. paper |
-
1998
- 1998-09-15 CA CA 2246115 patent/CA2246115A1/en not_active Abandoned
-
1999
- 1999-02-01 GB GB9902029A patent/GB2346440A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB2346440A (en) | 2000-08-09 |
| GB9902029D0 (en) | 1999-03-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |