1. A mixer, for use with an internal combustion engine, for mixing EGR gas from an EGR loop with fresh air from the engine’s fresh air intake, comprising:
an outer shell having the shape of a hollow cylinder with a side entry port, with one end of the cylinder providing an intake air entry port and the other end of the cylinder providing an intake air exit port;
a inner sleeve having a generally cylindrical shape, positioned inside the outer shell having an entry end that aligns with and fits within the intake air entry port and having an exit end that aligns with and fits within the intake air exit port, such that the inner sleeve provides a passageway through the mixer;
wherein the outer circumference of the inner sleeve is smaller than the inner circumference of the outer shell, such that a space is provided between the inner sleeve and the outer shell inside the mixer;
wherein the inner sleeve has one or more rows of flow ribs extending from its outer surface within the space over which air flows, each row extending traverse to the axial length of the inner sleeve; and
wherein the inner shell further has entry holes for providing fluid communication from the space into the passageway.
2. The mixer of claim 1, wherein the flow ribs each extend the same distance from the surface of the inner sleeve.
3. The mixer of claim 1, wherein the flow ribs extend progressively further from the surface of the inner sleeve.
4. The mixer of claim 1, wherein the flow ribs extend perpendicularly from the surface of the inner sleeve.
5. The mixer of claim 1, wherein the flow ribs extend from the surface of the inner sleeve at an angle.
6. The mixer of claim 1, wherein the flow ribs are separate and parallel to each other.
7. The mixer of claim 1, wherein the flow ribs are formed from at least one spiral rib extending from the outer surface of the inner sleeve.
8. The mixer of claim 1, wherein the mixer is operable to receive bursts of EGR gas and expel a near steady stream of mixed EGR gas and fresh air.
9. The mixer of claim 1, wherein the EGR loop is a dedicated EGR loop.
10. The mixer of claim 1, wherein the flow ribs extend completely across the space and have openings for allowing EGR gas to flow through the flow ribs.
11. A method of mixing EGR from an EGR loop with fresh air for subsequent introduction into the intake manifold of an internal combustion engine, the engine having a turbocharger with a compressor, comprising:
connecting a mixer to the EGR loop, to a fresh air intake line downstream the compressor, and to a mixed output line upstream the intake manifold;
wherein the mixer has an outer shell having the shape of a hollow cylinder with a side entry port to receive the EGR gas via the EGR loop, with one end of the cylinder providing an intake entry port to receive the fresh air and the other end of the cylinder providing an intake exit port to exhaust the mixed output;
a inner sleeve having a generally cylindrical shape, positioned inside the outer shell having an entry end that aligns with and fits within the intake entry port and having an exit end that aligns with and fits within the intake exit port, such that the inner sleeve provides a passageway; wherein the outer circumference of the inner sleeve is smaller than the inner circumference of the outer shell, such that a space is provided between the inner sleeve and the outer shell;
wherein the inner sleeve has one or more rows of flow ribs extending from its outer surface within the space over which air flows, each row extending traverse to the axial length of the inner sleeve; and
wherein the inner shell further has entry holes for providing fluid communication from the space into the passageway;
wherein the mixer is operable to receive bursts of EGR gas and to expel a near steady stream of mixed EGR gas and fresh air.
12. The method of claim 11, wherein the flow ribs each extend the same distance from the surface of the inner sleeve.
13. The method of claim 11, wherein the flow ribs extend progressively further from the surface of the inner sleeve.
14. The method of claim 11, wherein the flow ribs extend perpendicularly from the surface of the inner sleeve.
15. The method of claim 11, wherein the flow ribs extend from the surface of the inner sleeve at an angle.
16. The method of claim 11, wherein the flow ribs are separate and parallel to each other.
17. The method of claim 11, wherein the flow ribs are formed from at least one spiral rib extending from the outer surface of the inner sleeve.
18. The method of claim 11, wherein the EGR loop is a dedicated EGR loop.
19. The method of claim 11, wherein the flow ribs extend completely across the space and have openings for allowing EGR gas to flow through the flow ribs.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A scanning electron microscope device, comprising:
a scanning electron microscope;
a processor that composes an imaging recipe for imaging a specimen, which has patterns formed on the surface thereof, by the scanning electron microscope, and processes an image of the specimen obtained by imaging the specimen using the scanning electron microscope on the basis of the composed imaging recipe;
a dimensional information extractor that extracts dimensional information on a pattern, which is formed on the specimen, from the image of the specimen processed by the processor;
an inputoutput unit that inputs or outputs information to be processed by the processor and dimensional information extractor, information processed thereby, or design information on the specimen; and
a control unit that controls the microscope, processor, dimensional information extractor, and inputoutput unit,
wherein the processor includes:
an index value calculation unit that calculates, on the basis of the design information inputted by the inputoutput unit, index values each indicating whether images of adjoining areas out of the plurality of images can be joined or are easy to join,
a local imaging area group imaging recipe composition unit that composes an imaging recipe for a group of local imaging areas, which includes imaging areas of the respective images and an imaging magnification, on the basis of the index values which are calculated by the index value calculation unit and indicate easiness of joining, and
a local image group joining unit that controls the scanning electron microscope on the basis of the imaging recipe composed by the local imaging area group imaging recipe composition unit, sequentially images a plurality of adjoining areas on the specimen while overlapping the adjoin areas, and joining a plurality of resultant images so as to produce a wide-area image, and
wherein the dimensional information extractor extracts the dimensional information on the pattern from the wide-area image which the processor has produced by joining the plurality of images.
2. The scanning electron microscope device according to claim 1, wherein the control unit uses information on imaging areas, which is inputted from the inputoutput unit, and the design information on patterns to calculate an overlap width among images of a plurality of adjoining areas on the specimen which are picked up by the scanning electron microscope, and uses information on the calculated overlap width to control the scanning electron microscope so that the scanning electron microscope can image the specimen.
3. The scanning electron microscope device according to claim 1, wherein the specimen is an exposure mask, and the patterns are patterns having undergone optimal proximity correction.
4. A scanning electron microscope device comprising:
a scanning electron microscope;
an imaging recipe composer that composes an imaging recipe for imaging a specimen, which has patterns formed on the surface thereof, using the scanning electron microscope;
an image processor that processes an image of the specimen, which is obtained by imaging the specimen using the scanning electron microscope, on the basis of the imaging recipe composed by the imaging recipe composer;
a dimensional information extractor that extracts dimensional information on a pattern, which is formed on the specimen, from the image of the specimen processed by the image processor;
an inputoutput unit that includes a display screen and inputs or outputs information to be processed by the image processor and dimensional information extractor and information processed thereby; and
a control unit that controls the microscope, imaging recipe composer, image processor, dimensional information extractor, and inputoutput unit,
wherein the imaging recipe composer has a function of calculating index values (adjacent link information), each of which indicates whether two arbitrary adjoining local imaging areas can be joined or are easy to join, on the basis of a pattern, which is contained in an overlap area between the two arbitrary adjoining local imaging areas, as index values each indicating whether images of adjoining local imaging areas out of images of a plurality of local imaging areas into which a high-magnification image acquisition area designated using design information on the high-magnification image acquisition area designated on the screen of the inputoutput unit on which a low-magnification image of the specimen picked up by the scanning electron microscope is displayed is divided, calculating based on the index values, each of which indicates whether the two arbitrary adjoining local areas can be joined or are easy to join, an index value (arbitrary link information) that indicates whether two arbitrary local imaging areas can be joined or are easy to join, and composing an imaging recipe using the calculated index values,
wherein the control unit has a function of controlling the scanning electron microscope so as to allow the scanning electron microscope to image the local imaging areas at a high magnification on the basis of the imaging recipe composed by the imaging recipe composer,
wherein the image processor has a function of producing a high-magnification wide-area image by joining the high-magnification images of the local imaging areas picked up by the scanning electron microscope; and
wherein the dimensional information extractor has a function of extracting a dimension of the pattern from the high-magnification wide-area image produced by the image processor.
5. The scanning electron microscope device according to claim 4, wherein:
the function of the imaging recipe composer of dividing an area into a plurality of areas divides the high-magnification image acquisition area into the plurality of areas in a plurality of cases;
the inputoutput unit displays the cases of division into a plurality of areas, which the imaging recipe composer has dealt with, side by side on the display screen; and
the control unit controls the scanning electron microscope to allow the scanning electron microscope to image the divided areas on the bases of the case of division designated on the screen on which the cases are displayed side by side.
6. The scanning electron microscope device according to claim 4, wherein the imaging recipe composer uses image information on a high-magnification image acquisition area, which is designated on the screen on which the low-magnification image of the specimen is displayed, and design information on the designated high-magnification image acquisition area to divide the designated high-magnification image acquisition area into a plurality of areas so that adjoining areas overlap while containing part of the edge of the pattern.
7. The scanning electron microscope device according to claim 4, wherein the specimen is an exposure mask, and the patterns are patterns having undergone optical proximity correction.
8. A pattern dimension measuring method using a scanning electron microscope device, comprising:
imaging a specimen, which has patterns formed on the surface thereof, at a low magnification using a scanning electron microscope;
displaying the picked up low-magnification image of the specimen on a screen;
when design information on a high-magnification image acquisition area designated on the screen on which the low-magnification image is displayed is used to divide the designated high-magnification image acquisition area into a plurality of local imaging areas, calculating index values each of which indicates whether images of adjoining local imaging areas can be joined or are easy to join;
composing an imaging recipe for a group of local imaging areas, which includes imaging areas of the plurality of images and an imaging magnification, on the basis of the calculated index values which indicate easiness of joining;
imaging the divided local imaging areas using the scanning electron microscope on the basis of the composed imaging recipe so as to acquire high-magnification images of the local imaging areas;
joining the picked up high-magnification images of the respective local imaging areas so as to produce a high-magnification wide-area image; and
extracting a dimension of the pattern from the produced high-magnification wide-area image.
9. The pattern dimension measuring method using a scanning electron microscope device as set forth in claim 8, wherein the high-magnification image acquisition area is divided into a plurality of areas in a plurality of cases, the plurality of cases of division are displayed side by side on the display screen, the divided areas are imaged at a high magnification using the scanning electron microscope on the basis of the case of division designated on the screen on which the cases are displayed.
10. The pattern dimension measuring method using a scanning electron microscope device as set forth in claim 8, wherein at a step of composing the imaging recipe, image information on a high-magnification image acquisition area, which is designated on the screen on which the low-magnification image of the specimen is displayed, and design information on the designated high-magnification image acquisition area are used to divide the designated high-magnification image acquisition area into a plurality of areas so that adjoining areas overlap while containing part of the edge of the pattern.