CA2349995A1 - Viewing particles in a relatively translucent medium - Google Patents
Viewing particles in a relatively translucent medium Download PDFInfo
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- CA2349995A1 CA2349995A1 CA 2349995 CA2349995A CA2349995A1 CA 2349995 A1 CA2349995 A1 CA 2349995A1 CA 2349995 CA2349995 CA 2349995 CA 2349995 A CA2349995 A CA 2349995A CA 2349995 A1 CA2349995 A1 CA 2349995A1
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Abstract
Particles in a relatively translucent fluid stream passing through a conduit are viewed by illuminating the fluid and particles by passing light from an external light source through a window in the wall of the conduit, and viewing the illuminated fluid and particles through another window in the wall of the conduit by means of a telecentric lens and a charge coupled device camera both positioned externally of and spaced from the conduit wall to allow the telecentric lens to focus an image of the fluid and particles in the conduit for the charge coupled device camera.
Description
VIEWING PARTICLES IN A RELATIVELY
TRANSLUCENT MEDIUM
This invention relates to viewing particles in a relatively translucent medium. The invention is especially useful for, but is not limited to, viewing particles in a relatively translucent fluid stream such as a molten polymer stream flowing in an extruder.
BACKGROUND OF THE INVENTION
The presence of particles in a polymer melt stream during extrusion is a common occurrence. Some particles, such as processing additives or filler material, are intentionally added to the polymer melt. Other particles, such as microgels, burned material, void spaces, and secondary polymers or other materials carried in the primary polymer stream, may be undesirable contaminants which threaten product quality. The ability to monitor in real time the movement of particles in a melt stream, as well as to identify particle types, sizes, shapes, locations, concentrations and velocity profiles, provides a number of benefits. With respect to particles intentionally added to the melt, an effective monitoring system ensures that the desired dispersion ofparticles is achieved. With respect to particle contaminants in the melt, an effective monitoring system can be used to ensure that the polymer melt stream meets the required quality level for the process concerned. The use of a real time monitoring system can provide tighter process quality control, generate practical information on the mixing process during extrusion and greatly reduce off specification material waste.
Although the benefits of a real time monitoring system for polymer melt streams are numerous, very few attempts to develop a viable system have succeeded. One proposed monitoring system is described in U.S. Patent No. 4,529,306 (Kilham et al) which issued on July 16, 1985 and was permitted to expire on September 23, 1997. The Kilham et al system proposed the use of an observation probe and illuminating probes directly attached to the processing equipment to obtain images of the polymer melt. The observation probe consisted primarily of an objective lens for focussing an image onto a focal plane and an image-conducting means such as a fibre optic bundle. The use of an objective lens, as with all conventional lenses, can result in viewing angle errors and magnification errors which distort both the size and the shape of the objects being imaged. In addition, use of a conventional lens impedes the determination of the location of particles in the melt stream.
The use of observation and illumination probes directly attached to the processing equipment also causes complications because the probes must be removed from the high temperature and high pressure environment for maintenance purposes. Further, the Kilham et al system makes no provisions to reduce image blur caused by rapid movement of the objects to be imaged past the observation probe.
Another monitoring system is commercially available from Dynisco Polymer Test On-Line. The Dynisco Polymer Contaminants Analyzer (PCA) uses a sampling system which includes a flow cell, optical probes and fibre optic illumination and image bundles. The Dynisco PCA employs an on-line technique as opposed to an in-line technique.
On-line techniques divert a sampling stream of the flow to a measurement device, such as a flow cell.
TRANSLUCENT MEDIUM
This invention relates to viewing particles in a relatively translucent medium. The invention is especially useful for, but is not limited to, viewing particles in a relatively translucent fluid stream such as a molten polymer stream flowing in an extruder.
BACKGROUND OF THE INVENTION
The presence of particles in a polymer melt stream during extrusion is a common occurrence. Some particles, such as processing additives or filler material, are intentionally added to the polymer melt. Other particles, such as microgels, burned material, void spaces, and secondary polymers or other materials carried in the primary polymer stream, may be undesirable contaminants which threaten product quality. The ability to monitor in real time the movement of particles in a melt stream, as well as to identify particle types, sizes, shapes, locations, concentrations and velocity profiles, provides a number of benefits. With respect to particles intentionally added to the melt, an effective monitoring system ensures that the desired dispersion ofparticles is achieved. With respect to particle contaminants in the melt, an effective monitoring system can be used to ensure that the polymer melt stream meets the required quality level for the process concerned. The use of a real time monitoring system can provide tighter process quality control, generate practical information on the mixing process during extrusion and greatly reduce off specification material waste.
Although the benefits of a real time monitoring system for polymer melt streams are numerous, very few attempts to develop a viable system have succeeded. One proposed monitoring system is described in U.S. Patent No. 4,529,306 (Kilham et al) which issued on July 16, 1985 and was permitted to expire on September 23, 1997. The Kilham et al system proposed the use of an observation probe and illuminating probes directly attached to the processing equipment to obtain images of the polymer melt. The observation probe consisted primarily of an objective lens for focussing an image onto a focal plane and an image-conducting means such as a fibre optic bundle. The use of an objective lens, as with all conventional lenses, can result in viewing angle errors and magnification errors which distort both the size and the shape of the objects being imaged. In addition, use of a conventional lens impedes the determination of the location of particles in the melt stream.
The use of observation and illumination probes directly attached to the processing equipment also causes complications because the probes must be removed from the high temperature and high pressure environment for maintenance purposes. Further, the Kilham et al system makes no provisions to reduce image blur caused by rapid movement of the objects to be imaged past the observation probe.
Another monitoring system is commercially available from Dynisco Polymer Test On-Line. The Dynisco Polymer Contaminants Analyzer (PCA) uses a sampling system which includes a flow cell, optical probes and fibre optic illumination and image bundles. The Dynisco PCA employs an on-line technique as opposed to an in-line technique.
On-line techniques divert a sampling stream of the flow to a measurement device, such as a flow cell.
The sampled material is then either returned to the primary flow stream or discarded. In-line techniques directly monitor the primary flow stream. On-line techniques are generally easier to develop, since conditions in the measurement device can be tailored for ease of measurement. However, measurements made on a sampling stream may not accurately represent the primary flow stream since the sampling stream has experienced a different flow history. In addition, once the sampling stream has been tested, it must either be returned to the primary flow stream, which can introduce disturbances into the process, or it must be discarded, which results in material waste and disposal issues. Further, the use of a flow cell precludes obtaining information regarding the mixing, movement, location or velocity profile of the particles in the primary flow stream.
It is therefore an object of the present invention to provide an improved method and apparatus for viewing particles in a relatively translucent medium which method and apparatus are especially useful for viewing particles in a relatively translucent fluid stream such as a molten polymer stream flowing in an extruder.
SLITvIMARY OF THE INVENTION
According to one aspect of the invention, a method of viewing particles in a relatively translucent fluid stream passing through a conduit includes illuminating the fluids and particles therein by passing light from an external light source through a window in the wall of the conduit, and viewing the illuminated fluid and particles through another window in the wall of the conduit by means of a telecentric lens and a charge coupled device camera both positioned externally of and spaced from the conduit wall to allow the telecentric lens to focus an image of the fluid and particles in the conduit for the charge coupled device camera.
The telecentric lens may be mounted on a base, with adjustment mechanism being provided for adjusting the position of the telecentric lens on the base. A
computer may be coupled to the charge coupled device camera to manipulate images therefrom.
According to a further aspect of the invention, apparatus is provided for viewing particles in a relatively translucent fluid stream passing through a conduit, the conduit having a wall with a window for receiving light from an external light source and transmitting the light into the conduit to illuminate the fluid and particles, the conduit also having a further window through which the illuminated fluid and particles can be observed. The apparatus includes a telecentric lens and a charge coupled device camera positioned externally of and spaced from the conduit wall to enable the telecentric lens to focus an image of the fluid and particles in the conduit for the charge coupled device camera.
According to a still further aspect of the invention, apparatus for viewing particles in a relatively translucent medium includes a telecentric lens and a charge coupled device camera positionable adjacent the medium to enable the telecentric lens to form an image of the medium and particles therein for the charge coupled device camera when the medium is illuminated by light.
DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which Fig. 1 is a schematic view of the apparatus for viewing particles in a polymer melt stream flowing in an extruder, Fig. 2 is a side view of the extruder and interface assembly, and Fig. 3 is a cross-sectional view taken along the line 3-3 of Fig. 2, the window assemblies being shown in exploded form.
The drawings are not necessarily to scale and, in some instances, proportions may have been exaggerated in order to depict more clearly certain features of the embodiment.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings, Fig. 1 shows a front view of an extruder and interface assembly 10. A molten polymer stream exits the extruder from a melt channel or conduit 12.
The interface includes four window bolts 14-1 to 14-4 which will be described in greater detail later. A conventional band heater 16 is secured to the exterior of the extruder and interface assembly 10, and heater cables 18-1 and 18-2 carry electrical power to the band heater 16.
A light source 60 provides high intensity light, typically produced by either a halogen lamp for white light or a mercury lamp for ultraviolet light. In this embodiment, light source 60 is connected to a light guide 62 which transmits the light to window bolt 14-1 to illuminate the molten polymer contained in melt channel 12.
It is therefore an object of the present invention to provide an improved method and apparatus for viewing particles in a relatively translucent medium which method and apparatus are especially useful for viewing particles in a relatively translucent fluid stream such as a molten polymer stream flowing in an extruder.
SLITvIMARY OF THE INVENTION
According to one aspect of the invention, a method of viewing particles in a relatively translucent fluid stream passing through a conduit includes illuminating the fluids and particles therein by passing light from an external light source through a window in the wall of the conduit, and viewing the illuminated fluid and particles through another window in the wall of the conduit by means of a telecentric lens and a charge coupled device camera both positioned externally of and spaced from the conduit wall to allow the telecentric lens to focus an image of the fluid and particles in the conduit for the charge coupled device camera.
The telecentric lens may be mounted on a base, with adjustment mechanism being provided for adjusting the position of the telecentric lens on the base. A
computer may be coupled to the charge coupled device camera to manipulate images therefrom.
According to a further aspect of the invention, apparatus is provided for viewing particles in a relatively translucent fluid stream passing through a conduit, the conduit having a wall with a window for receiving light from an external light source and transmitting the light into the conduit to illuminate the fluid and particles, the conduit also having a further window through which the illuminated fluid and particles can be observed. The apparatus includes a telecentric lens and a charge coupled device camera positioned externally of and spaced from the conduit wall to enable the telecentric lens to focus an image of the fluid and particles in the conduit for the charge coupled device camera.
According to a still further aspect of the invention, apparatus for viewing particles in a relatively translucent medium includes a telecentric lens and a charge coupled device camera positionable adjacent the medium to enable the telecentric lens to form an image of the medium and particles therein for the charge coupled device camera when the medium is illuminated by light.
DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which Fig. 1 is a schematic view of the apparatus for viewing particles in a polymer melt stream flowing in an extruder, Fig. 2 is a side view of the extruder and interface assembly, and Fig. 3 is a cross-sectional view taken along the line 3-3 of Fig. 2, the window assemblies being shown in exploded form.
The drawings are not necessarily to scale and, in some instances, proportions may have been exaggerated in order to depict more clearly certain features of the embodiment.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings, Fig. 1 shows a front view of an extruder and interface assembly 10. A molten polymer stream exits the extruder from a melt channel or conduit 12.
The interface includes four window bolts 14-1 to 14-4 which will be described in greater detail later. A conventional band heater 16 is secured to the exterior of the extruder and interface assembly 10, and heater cables 18-1 and 18-2 carry electrical power to the band heater 16.
A light source 60 provides high intensity light, typically produced by either a halogen lamp for white light or a mercury lamp for ultraviolet light. In this embodiment, light source 60 is connected to a light guide 62 which transmits the light to window bolt 14-1 to illuminate the molten polymer contained in melt channel 12.
An opto-mechanical assembly 100 includes a telecentric lens 102 with an extra-long working distance which forms images of the molten polymer contained in the melt channel 12 through window bolt 14-3. The telecentric lens 102 focuses an image of the molten polymer for a charge coupled device camera 104. The lens 102 and camera 104 may be connected by a standard optical C- mount. The camera 104 may be a color progressive scan charge coupled device camera with an electronic shutter. A cable 106 carries electronic information between the camera 104 and a computer 108 which will be described in greater detail later. Cable 110 carries power to the camera 104. Multiple opto-mechanical assemblies may also be a feature of the present invention.
A lens bracket 112 is clamped around the body of the lens 102 and is attached to a mounting plate 114, thereby securing the lens 102 and camera 104 to mounting plate 114.
Mounting plate 114 attaches the lens bracket 112 to a translation stage 116.
At a minimum, an upper plate of the translation stage 116 can move closer to or further from the extruder and interface assembly 10. However, additional movement in any other direction may also be a feature of the present invention. An actuator 118 moves the upper plate of translation stage 116 and may indicate the position of the stage relative to an initial setting. By changing the position of translation stage 116, the lens 102 and camera 104 can produce images of the molten polymer at varying depths in the melt channel 12. Typically, the lens 102 and camera 104 can "scan" across the melt channel 12 in thin optical sections to produce images of the molten polymer from one wall of the melt channel to the other. In this embodiment, the actuator 118 is manually controlled. Alternatively, the actuator may be motorized and controlled remotely and/or automatically.
A mounting plate 120 attaches the translation stage 116 to a tripod mount 122.
In this embodiment, the tripod mount 122 is equipped with slow motion precision controllers 124-1 and 124-2. Precision controller 124-1 controls the up and down, or "tilting"
motion oftripod mount 122. Precision controller 124-2 controls the side-to-side, or "panning"
motion, of tripod mount 122. In addition, tripod mount 122 has a coarse controller 126 to control large scale panning motions. Tripod mount 122 is attached to a tripod 128. A typical tripod has adjustable legs to change the height thereof. The controllers 124-1, 124-2 and 126, in conjunction with an adjustable tripod, are used to control the alignment of lens 102 with window bolt 14-3 and, more generally, are used to provide flexibility in the positioning of the opto-mechanical assembly 100.
Computer 108 is equipped with a color frame grabber and imaging softvvare. The frame grabber is used to capture and record video information from camera 104.
The 1 S imaging software provides tools for processing, enhancing and quantitatively analyzing the images acquired by the frame grabber. The computer 108 may also be linked to a process control system. Power source 150 provides power to light source 60, heater cables 18-1 and 18-2, camera cable 110 and computer 108.
Referring now to Fig. 2, molten polymer flows from the extruder 24 to the interface 26 and exits from the melt channel 12 through a die piece 28. The interface 26 may be constructed of steel. The extruder 24 is attached to the interface 26 by a flange 30. Two band heaters 16, 20 are secured to the exterior of the interface 26 to ensure that the molten polymer remains at the desired temperature. Heater cables 18-1 and 22- l, together with two identical heater cables (not shown) carry power to band heaters 16, 20. Window bolts 14-1 and 14-4 are also shown and will be described in more detail later.
Fig. 3 shows window bolts 14-1 to 14-4, window gaskets 40-1 to 40-4 and windows 42-1 to 42-4 removed from the interface ports 44-1 to 44-4 for greater clarity. The melt channel 12 is axially concentric with the interface 26. In this embodiment, four cylindrical interface ports 44-1 to 44-4 are bored through the walls of the interface 26 and the melt channel 12. Fig. 1 shows a light guides 62 positioned at port 44-1 and lens 102 positioned at port 44-3. The lens 102 may be positioned at any one of the interface ports 44-1 to 44-4, and light guide or guides 62 may be positioned at any of the other ports. The interface ports 44-1 to 44-4 are positioned at various angles around the circumference of the melt channel. These angles are selected to provide flexibility in illumination techniques, whereas the optimum lighting configuration and choice of light source are determined by the type of molten polymer and particles to be imaged.
Each interface port 44-1 to 44-4 houses a sapphire window 42-1 to 42-4 which sits directly adjacent to the molten polymer in the melt channel 12, a copper window gasket 40-1 to 40-4 which sits on top of the window 42-1 to 42-4, and a window bolt 14-1 to 14-4 which clamps down on the gasket 40-1 to 40-4 and window 42-1 to 42-4 to hold them securely in place. In this embodiment, the centres of window bolts 14-1 and 14-3 have been bored out along the length of the bolts so that the bolts are hollow, whereas window bolts 14-2 and _g-14-4 are solid. When an interface port 44-1 to 44-4 is being used for either illumination or imaging purposes, a hollow bolt is used to allow access to the sapphire window at the base of the port. When an interface port is not is use, a solid bolt is used to block out stray light.
The inner walls of the interface ports 44-1 to 44-4 are threaded to allow the window bolts 14-S 1 to 14-4 to be screwed into place.
Although the above described embodiment is based on the use of an interface 26 which fits between an extruder 24 and a die piece 28, the present invention is not limited to the use of such an interface. In lieu of an interface 26, two interface ports, including windows, gaskets and bolts, may be placed closely enough together to allow sufficient illumination to be delivered through one port so that an image can be acquired at the second port. These ports can be located anywhere along an extrusion line, provided that there is sufficient surrounding space to position the light source 60 and the opto-mechanical assembly 100 at the appropriate ports.
Unlike the Kilham et al system or the Dynisco PCA system, the optical equipment of the present invention is external to the polymer processing equipment. Thus, with the present invention, the optical equipment is not subjected to the high temperature and high pressure environment in the processing equipment. In addition, since the opto-mechanical assembly of the present invention is not attached to such processing equipment, it is portable. The assembly can be moved from an interface port on one processing line to an interface port on an entirely separate processing line or the assembly can be moved between ports located on the same line.
The present invention utilizes a telecentric lens instead of an objective or conventional lens. Unlike an objective lens, the telecentric lens produces an image in which objects are dimensionally accurate, regardless of viewing angle or proximity to the lens.
This characteristic greatly reduces distortion of the image, thereby allowing more accurate quantitative information with respect to particle size, shape and location to be obtained. The telecentric lens also has the ability to provide images of thin optical sections of the fluid stream. By changing the position of the lens, it is possible to select which thin optical section in the fluid stream is imaged. Further, by changing the aperture setting of the lens, the thickness of each optical section can be adjusted. With the combination of the telecentric lens and the moving translation stage, the present invention has the ability to scan across the fluid stream in thin optical sections, allowing images to be captured at any depth in the conduit. In addition, the actuator which is used to move the translation stage can indicate the position in the conduit being imaged relative to an initial zero setting. This provides quantitative information on the location of the particles in the conduit which, in turn, permits 1 S the determination of information such as particle velocity profiles and mixing behaviour of the particles in the fluid and of the fluid itself. Further, images captured at different depths in the conduit may be combined to yield three-dimensional reconstructions of the fluid stream and the particles thereof.
Prior art imaging systems have been plagued by poor image quality, since fast moving particles often appear blurry or even as streaks in an image. The present invention enables blur to be reduced by various measures. The charge coupled device camera may use progressive scan technology and an electronic shutter to greatly reduce image blur. In addition, as mentioned previously, the telecentric lens has the ability to provide images of thin optical sections of the fluid stream. This means that objects outside of the optical section, i.e. objects that are out of focus, are not imaged by the lens, thereby reducing the blurriness of the image.
In general, the type and wavelength of light used, the number of light sources, the number of light guides, and the configuration of the light sources) and light guides) are selected based on the objects to be imaged. Further, the light may not be transmitted through the fluid or medium but instead may be introduced from the same side as the lens or from any other angle as to produce a desirable image.
Other embodiments of the invention will now be readily apparent to a person skilled in the art from the above description, the scope of the invention being defined in the appended claims.
A lens bracket 112 is clamped around the body of the lens 102 and is attached to a mounting plate 114, thereby securing the lens 102 and camera 104 to mounting plate 114.
Mounting plate 114 attaches the lens bracket 112 to a translation stage 116.
At a minimum, an upper plate of the translation stage 116 can move closer to or further from the extruder and interface assembly 10. However, additional movement in any other direction may also be a feature of the present invention. An actuator 118 moves the upper plate of translation stage 116 and may indicate the position of the stage relative to an initial setting. By changing the position of translation stage 116, the lens 102 and camera 104 can produce images of the molten polymer at varying depths in the melt channel 12. Typically, the lens 102 and camera 104 can "scan" across the melt channel 12 in thin optical sections to produce images of the molten polymer from one wall of the melt channel to the other. In this embodiment, the actuator 118 is manually controlled. Alternatively, the actuator may be motorized and controlled remotely and/or automatically.
A mounting plate 120 attaches the translation stage 116 to a tripod mount 122.
In this embodiment, the tripod mount 122 is equipped with slow motion precision controllers 124-1 and 124-2. Precision controller 124-1 controls the up and down, or "tilting"
motion oftripod mount 122. Precision controller 124-2 controls the side-to-side, or "panning"
motion, of tripod mount 122. In addition, tripod mount 122 has a coarse controller 126 to control large scale panning motions. Tripod mount 122 is attached to a tripod 128. A typical tripod has adjustable legs to change the height thereof. The controllers 124-1, 124-2 and 126, in conjunction with an adjustable tripod, are used to control the alignment of lens 102 with window bolt 14-3 and, more generally, are used to provide flexibility in the positioning of the opto-mechanical assembly 100.
Computer 108 is equipped with a color frame grabber and imaging softvvare. The frame grabber is used to capture and record video information from camera 104.
The 1 S imaging software provides tools for processing, enhancing and quantitatively analyzing the images acquired by the frame grabber. The computer 108 may also be linked to a process control system. Power source 150 provides power to light source 60, heater cables 18-1 and 18-2, camera cable 110 and computer 108.
Referring now to Fig. 2, molten polymer flows from the extruder 24 to the interface 26 and exits from the melt channel 12 through a die piece 28. The interface 26 may be constructed of steel. The extruder 24 is attached to the interface 26 by a flange 30. Two band heaters 16, 20 are secured to the exterior of the interface 26 to ensure that the molten polymer remains at the desired temperature. Heater cables 18-1 and 22- l, together with two identical heater cables (not shown) carry power to band heaters 16, 20. Window bolts 14-1 and 14-4 are also shown and will be described in more detail later.
Fig. 3 shows window bolts 14-1 to 14-4, window gaskets 40-1 to 40-4 and windows 42-1 to 42-4 removed from the interface ports 44-1 to 44-4 for greater clarity. The melt channel 12 is axially concentric with the interface 26. In this embodiment, four cylindrical interface ports 44-1 to 44-4 are bored through the walls of the interface 26 and the melt channel 12. Fig. 1 shows a light guides 62 positioned at port 44-1 and lens 102 positioned at port 44-3. The lens 102 may be positioned at any one of the interface ports 44-1 to 44-4, and light guide or guides 62 may be positioned at any of the other ports. The interface ports 44-1 to 44-4 are positioned at various angles around the circumference of the melt channel. These angles are selected to provide flexibility in illumination techniques, whereas the optimum lighting configuration and choice of light source are determined by the type of molten polymer and particles to be imaged.
Each interface port 44-1 to 44-4 houses a sapphire window 42-1 to 42-4 which sits directly adjacent to the molten polymer in the melt channel 12, a copper window gasket 40-1 to 40-4 which sits on top of the window 42-1 to 42-4, and a window bolt 14-1 to 14-4 which clamps down on the gasket 40-1 to 40-4 and window 42-1 to 42-4 to hold them securely in place. In this embodiment, the centres of window bolts 14-1 and 14-3 have been bored out along the length of the bolts so that the bolts are hollow, whereas window bolts 14-2 and _g-14-4 are solid. When an interface port 44-1 to 44-4 is being used for either illumination or imaging purposes, a hollow bolt is used to allow access to the sapphire window at the base of the port. When an interface port is not is use, a solid bolt is used to block out stray light.
The inner walls of the interface ports 44-1 to 44-4 are threaded to allow the window bolts 14-S 1 to 14-4 to be screwed into place.
Although the above described embodiment is based on the use of an interface 26 which fits between an extruder 24 and a die piece 28, the present invention is not limited to the use of such an interface. In lieu of an interface 26, two interface ports, including windows, gaskets and bolts, may be placed closely enough together to allow sufficient illumination to be delivered through one port so that an image can be acquired at the second port. These ports can be located anywhere along an extrusion line, provided that there is sufficient surrounding space to position the light source 60 and the opto-mechanical assembly 100 at the appropriate ports.
Unlike the Kilham et al system or the Dynisco PCA system, the optical equipment of the present invention is external to the polymer processing equipment. Thus, with the present invention, the optical equipment is not subjected to the high temperature and high pressure environment in the processing equipment. In addition, since the opto-mechanical assembly of the present invention is not attached to such processing equipment, it is portable. The assembly can be moved from an interface port on one processing line to an interface port on an entirely separate processing line or the assembly can be moved between ports located on the same line.
The present invention utilizes a telecentric lens instead of an objective or conventional lens. Unlike an objective lens, the telecentric lens produces an image in which objects are dimensionally accurate, regardless of viewing angle or proximity to the lens.
This characteristic greatly reduces distortion of the image, thereby allowing more accurate quantitative information with respect to particle size, shape and location to be obtained. The telecentric lens also has the ability to provide images of thin optical sections of the fluid stream. By changing the position of the lens, it is possible to select which thin optical section in the fluid stream is imaged. Further, by changing the aperture setting of the lens, the thickness of each optical section can be adjusted. With the combination of the telecentric lens and the moving translation stage, the present invention has the ability to scan across the fluid stream in thin optical sections, allowing images to be captured at any depth in the conduit. In addition, the actuator which is used to move the translation stage can indicate the position in the conduit being imaged relative to an initial zero setting. This provides quantitative information on the location of the particles in the conduit which, in turn, permits 1 S the determination of information such as particle velocity profiles and mixing behaviour of the particles in the fluid and of the fluid itself. Further, images captured at different depths in the conduit may be combined to yield three-dimensional reconstructions of the fluid stream and the particles thereof.
Prior art imaging systems have been plagued by poor image quality, since fast moving particles often appear blurry or even as streaks in an image. The present invention enables blur to be reduced by various measures. The charge coupled device camera may use progressive scan technology and an electronic shutter to greatly reduce image blur. In addition, as mentioned previously, the telecentric lens has the ability to provide images of thin optical sections of the fluid stream. This means that objects outside of the optical section, i.e. objects that are out of focus, are not imaged by the lens, thereby reducing the blurriness of the image.
In general, the type and wavelength of light used, the number of light sources, the number of light guides, and the configuration of the light sources) and light guides) are selected based on the objects to be imaged. Further, the light may not be transmitted through the fluid or medium but instead may be introduced from the same side as the lens or from any other angle as to produce a desirable image.
Other embodiments of the invention will now be readily apparent to a person skilled in the art from the above description, the scope of the invention being defined in the appended claims.
Claims (10)
1. A method of viewing particles in a relatively translucent fluid stream passing through a conduit, the method including:
illuminating the fluid and particles therein by passing light from an external light source through a window in the wall of the conduit, and viewing the illuminated fluid and particles through another window in the wall of the conduit by means of a telecentric lens and a charge coupled device camera both positioned externally of and spaced from the conduit wall to allow the telecentric lens to focus an image of the fluid and particles in the conduit for the charge coupled device camera.
illuminating the fluid and particles therein by passing light from an external light source through a window in the wall of the conduit, and viewing the illuminated fluid and particles through another window in the wall of the conduit by means of a telecentric lens and a charge coupled device camera both positioned externally of and spaced from the conduit wall to allow the telecentric lens to focus an image of the fluid and particles in the conduit for the charge coupled device camera.
2. A method according to claim 1 including mounting the telecentric lens on a base, and providing adjustment mechanisms for adjusting the position of the telecentric lens.
3. A method according to claim 1 including coupling a computer to the charge coupled device camera to manipulate images therefrom.
4. A method according to claim 1 wherein the relatively translucent fluid stream is a polymer melt stream in an extruder.
5. Apparatus for viewing particles in a relatively translucent fluid stream passing along a conduit, said conduit having a wall with a window for receiving light from an external light source and transmitting said light into the conduit to illuminate the fluid and particles, said conduit also having a further window through which the illuminated fluid and particles can be observed, said apparatus including:
a telecentric lens and a charge coupled device camera positioned externally of and spaced from the conduit wall to enable the telecentric lens to focus an image of the fluid and particles in the conduit for the charge coupled device camera.
a telecentric lens and a charge coupled device camera positioned externally of and spaced from the conduit wall to enable the telecentric lens to focus an image of the fluid and particles in the conduit for the charge coupled device camera.
6. Apparatus according to claim 5 also including a base, said telecentric lens being mounted on said base, and adjustment mechanism for adjusting the position of the telecentric lens on the base.
7. Apparatus according to claim 5 also including a computer coupled to the charge coupled device camera and operable to manipulate images therefrom.
8. Apparatus for viewing particles in a relatively translucent medium, said apparatus including:
a telecentric lens and a charge coupled device camera positionable adjacent the medium to enable the telecentric lens to form an image of the medium and particles therein for the charged coupled device camera when the medium is illuminated.
a telecentric lens and a charge coupled device camera positionable adjacent the medium to enable the telecentric lens to form an image of the medium and particles therein for the charged coupled device camera when the medium is illuminated.
9. Apparatus according to claim 8 also including a base, said telecentric lens being mounted on said base, and adjustment mechanism for adjusting the position of the telecentric lens on the base.
10. Apparatus according to claim 8 also including a computer coupled to the charge coupled device camera and operable to manipulate images therefrom.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60428400A | 2000-06-14 | 2000-06-14 | |
| US09/604,284 | 2000-06-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2349995A1 true CA2349995A1 (en) | 2001-12-14 |
Family
ID=24418991
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2349995 Abandoned CA2349995A1 (en) | 2000-06-14 | 2001-06-11 | Viewing particles in a relatively translucent medium |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2349995A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9470618B2 (en) | 2013-03-15 | 2016-10-18 | Iris International, Inc. | Sheath fluid systems and methods for particle analysis in blood samples |
| US9702806B2 (en) | 2013-03-15 | 2017-07-11 | Iris International, Inc. | Hematology systems and methods |
| US9857361B2 (en) | 2013-03-15 | 2018-01-02 | Iris International, Inc. | Flowcell, sheath fluid, and autofocus systems and methods for particle analysis in urine samples |
-
2001
- 2001-06-11 CA CA 2349995 patent/CA2349995A1/en not_active Abandoned
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9470618B2 (en) | 2013-03-15 | 2016-10-18 | Iris International, Inc. | Sheath fluid systems and methods for particle analysis in blood samples |
| US9702806B2 (en) | 2013-03-15 | 2017-07-11 | Iris International, Inc. | Hematology systems and methods |
| US9857361B2 (en) | 2013-03-15 | 2018-01-02 | Iris International, Inc. | Flowcell, sheath fluid, and autofocus systems and methods for particle analysis in urine samples |
| US9909973B2 (en) | 2013-03-15 | 2018-03-06 | Iris International, Inc. | Flowcell systems and methods for particle analysis in blood samples |
| US10060846B2 (en) | 2013-03-15 | 2018-08-28 | Iris International, Inc. | Hematology systems and methods |
| US10345217B2 (en) | 2013-03-15 | 2019-07-09 | Iris International, Inc. | Flowcell systems and methods for particle analysis in blood samples |
| US10451612B2 (en) | 2013-03-15 | 2019-10-22 | Iris International, Inc. | Sheath fluid systems and methods for particle analysis in blood samples |
| US10705008B2 (en) | 2013-03-15 | 2020-07-07 | Iris International, Inc. | Autofocus systems and methods for particle analysis in blood samples |
| US10794900B2 (en) | 2013-03-15 | 2020-10-06 | Iris International, Inc. | Flowcell, sheath fluid, and autofocus systems and methods for particle analysis in urine samples |
| US11525766B2 (en) | 2013-03-15 | 2022-12-13 | Iris International, Inc. | Dynamic range extension systems and methods for particle analysis in blood samples |
| US11543340B2 (en) | 2013-03-15 | 2023-01-03 | Iris International, Inc. | Autofocus systems and methods for particle analysis in blood samples |
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