All The Claims

That which is claimed is:

1. A method for the management of interrupts in a microprocessor, said interrupts having a two-fold order of priority, on the one hand a software priority and on the other hand a hardware priority, the microprocessor working in two modes, a first mode during which the execution of an interrupt routine cannot be interrupted by the arrival of a new interrupt, even if it is a priority interrupt, unless this new interrupt is non-maskable, a second mode during which the execution of an interrupt routine is interrupted by the arrival of a priority interrupt, the mode of operation of the microprocessor being conditioned by the software priority level of the interrupts,
wherein, at the time of the execution of an interrupt, its software priority level is loaded into the state register of the microprocessor.
2. A method for the management of interrupts according to claim 1, wherein the execution of an interrupt routine in progress is interrupted by the arrival of a new interrupt if the software priority level of this interrupt is higher than that of the interrupt in progress.
3. A method for the management of interrupts according to claim 2 wherein, in order that the microprocessor may function in the first mode, one and the same software priority level is assigned to each interrupt.
4. A method for the management of interrupts according to claim 2 or 3, wherein the software priority level assigned to each interrupt is encoded on n bits and wherein said n bits to be loaded into the state register of the microprocessor are contained in n distinct registers.
5. A method for the management of interrupts according to claim 4, wherein the software priority level is encoded on two bits and wherein the highest software priority level is 11 and the lowest software priority level is 10.
6. A method for the management of interrupts according to claim 1, wherein the execution of an interrupt routine in progress is interrupted by the arrival of a new interrupt if the software priority level of this interrupt is greater than that of the interrupt in progress.

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. Apparatus for photoacoustic (PA) imaging of a subject, said apparatus comprising:
a light positioned to illuminate said subject to generate PA waves emanating from said subject;
a programmed computer system;
a staring array of transducers for receiving said PA waves and converting said PA waves to corresponding analog signals, said staring array having at least three transducers and arranged in at least three dimensions and wherein three-dimensional (3-D) spatial co-ordinates of the transducers is to be determined by the programmed computer system;
an acoustically transmissive medium which surrounds the transducers and acoustically couples said staring array to said subject;
at least one analog to digital converter configured to receive said analog signals and convert said analog signals to corresponding digital signals; and
the programmed computer system operatively connected to said at least one analog to digital converter to receive said digital signals and configured to:
calibrate, at least when 3D spatial co-ordinates of the transducers is to be determined by the programmed computer system, the acoustic response of each of the transducers by measurements of PA waves from a PA source at a known plurality of positions, predetermined by the programmed computer system, through a calibration volume to generate at least three-dimensional (3-D) characterization maps for each transducer, and
process said digital signals, received when the staring array is staring, by an image reconstruction algorithm to create one or more three dimensional (3-D) images of said subject, said image reconstruction algorithm utilizes the three-dimensional (3-D) characterization maps for at least some of the transducers.
2. An apparatus according to claim 1 wherein said light comprises a laser capable of providing a pulsed laser beam.
3. An apparatus according to claim 2 including at least one photo detector, comprising a photo diode, configured to detect the illumination from said pulsed laser beam and providing digital signals indicative thereof to said computer system.
4. An apparatus according to claim 3 further comprising a relatively thin, optically transparent, window formed of acoustically transparent material for separating said subject from said staring array, wherein, during use of said apparatus, the illumination from said laser beam passes through said relatively thin, optically transparent, acoustically transparent window in order to illuminate said subject and said PA waves from said subject pass through said relatively thin, optically transparent, acoustically transparent material to said staring array.
5. An apparatus according to claim 2 wherein said laser is tunable.
6. An apparatus according to claim 1 wherein said light is located to illuminate said subject from a same side of the subject as a side on which said staring array is located.
7. An apparatus according to claim 1 wherein said staring array is an annular array, further comprising a supporting structure including an annular holder having said transducers distributed around an annular surface of said annular holder and defining a central hole, and said central hole is covered by an optical window made of an optically transparent material.
8. An apparatus according to claim 7 wherein said annular holder includes an annular wedge-shaped section having a flat annular side on which said transducers are mounted and creating a focal zone above a center of said staring array and wherein, during use of said apparatus, said PA waves are refracted by said wedge-shaped section before being transmitted to said transducers.
9. An apparatus according to claim 1 wherein said staring array is a hemispherical array, further comprising a supporting structure includes a plurality of transducer mounts each having one or more transducers mounted thereon at predetermined elevation angles, and said transducer mounts are arranged in a circle around a central hole which is covered by an optical window made of an optically transparent material.
10. An apparatus according to claim 1 further comprising a supporting structure for mounting said staring array wherein said staring array and said supporting structure are part of a transportable device which can be held in a user’s hand during use of the apparatus.
11. An apparatus according to claim 1 further comprising a tank which holds the acoustically transmissive medium.
12. An apparatus according to claim 3 wherein said computer system is configured to normalize said digital signals to measured illumination.
13. An apparatus according to claim 2 wherein said computer system is operatively connected to said laser and programmed to control said laser, and said computer system is also programmed to coordinate the operation of said at least one analog to digital converter with the operation of said laser.
14. An apparatus according to claim 1 wherein said image reconstruction algorithm is an iterative forward projecting, back projecting image reconstruction algorithm.
15. An apparatus according to claim 1, further comprising:
a laser source configured to produce a pulsed laser beam;
an optical fiber configured to receive said pulsed laser beam and generate said PA waves as said PA source at one end of said optical fiber when a pulse of laser beam illuminates said optical fiber; and
a scanner configured to move at least a portion of said optical fiber through the calibration volume.
16. An apparatus according to claim 15 wherein said one end of the optical fiber comprises an opaque coated tip of the optical fiber.
17. An apparatus according to claim 1 wherein said image reconstruction algorithm reconstructs the one or more three dimensional (3-D) images of said subject based on received corresponding digital signals for at least some but not all of the transducers.
18. An apparatus according to claim 17 wherein said image reconstruction algorithm reconstructs the one or more three dimensional (3-D) images of said subject using the three-dimensional (3-D) characterization maps for at least some but not all of the transducers due to additional material located between said subject and which interfere with coupling of said PA waves from said subject to at least one of the remaining transducers.
19. An apparatus according to claim 17 wherein said image reconstruction algorithm reconstructs the one or more three dimensional (3-D) images of said subject using the three-dimensional (3-D) characterization maps for at least some but not all of the transducers due to missing or incomplete data associated with at least one of the remaining transducers.
20. An apparatus according to claim 1 wherein the 3-D characterization maps includes, specific to each pair comprising a respective one of said transducers and said PA source position, at least one or all of: estimates of time of flight of said PA waves, amplitude of said PA waves, temporal width of said PA waves, shape of said PA waves, dampening of said PA waves, and frequency content of said PA waves.
21. An apparatus according to claim 1 wherein the staring array further comprises a staring sparse array, wherein said transducers are spaced apart from one another in order to provide a wider range of viewing angles of said subject compared to viewing angles achievable with an equivalent number of closer spaced transducers and without said calibration.
22. A method for photoacoustic (PA) imaging of a subject using a staring array of transducers for receiving said PA waves and converting said PA waves to corresponding signals, said staring array having at least three transducers and arranged in at least three dimensions and wherein three-dimensional (3-D) spatial co-ordinates of the transducers is to be determined by a programmed computer system, and an acoustically transmissive medium which surrounds the transducers and acoustically couples said staring array to said subject, said method comprising:
calibrating, at least when 3D spatial co-ordinates of the transducers is to be determined by the programmed computer system, the acoustic response of each of the transducers by measurements of PA waves from a PA source at a known plurality of positions, predetermined by the programmed computer system, through a calibration volume, and generating three-dimensional (3-D) characterization maps for each transducer, and estimating a position of each transducer element relative to the calibration volume;
illuminating said subject to generate PA waves emanating from said subject;
creating, based on signals received from the transducers when the staring array is staring, and utilizing the three-dimensional (3-D) characterization maps for at least some of the transducers, one or more three dimensional (3-D) images of said subject.
23. A method according to claim 22 wherein said PA source comprises a laser capable of providing a pulsed laser beam.
24. A method according to claim 22 wherein the said generating the 3-D characterization maps includes providing at least one or all of: estimates of time of flight of said PA waves, amplitude of said PA waves, temporal width of said PA waves, shape of said PA waves, dampening of said PA waves, and frequency content of said PA waves, specific to each pair comprising a respective one of said transducers and said PA source position.
25. A method according claim 22 wherein said generating the 3-D characterization maps includes calculating properties of said array, including number of said transducers sensitive to each grid point, angular acceptance of said transducers, and number of said grid points where PA waves are detectable for each transducer.
26. A method according to claim 23 including recording the power of each laser pulse, and monitoring fluctuations in the power of the pulses of the laser beam.
27. A method according to claim 22 wherein the staring array further includes a staring sparse array, wherein said transducers are spaced apart from one another in order to provide a wider range of viewing angles of said subject compared to viewing angles achievable with an equivalent number of closer spaced transducers and without said calibrating.

1. A string for use in a string ribbon crystal comprising a crystal material, the crystal material being one of silicon, silicon-germanium, gallium arsenide and indium phosphide, the string comprising:
a substrate;
a refractory layer supported on the substrate; and
an externally exposed layer having a contact angle with the crystal material of between about 15 and 120 degrees, the externally exposed layer being radially outward of the refractory layer.
2. The string as defined by claim 1 further comprising a handling layer radially outward of the refractory layer, the handling layer applying a generally radially inward force to the refractory layer.
3. The string as defined by claim 2 wherein the handling layer includes the externally exposed layer.
4. The string as defined by claim 2 wherein the externally exposed layer is radially outward of the handling layer.
5. The string as defined by claim 1 wherein the externally exposed layer comprises at least one of pyrolytic carbon, oxide, and nitride.
6. The string as defined by claim 1 wherein the externally exposed layer has a contact angle with the crystal material of greater than about 25 degrees.
7. The string as defined by claim 1 wherein the substrate comprises carbon, the refractory layer comprising silicon carbide.
8. The string as defined by claim 1 wherein the crystal material has a material coefficient of thermal expansion, the substrate, refractory layer, and exposed layer having a combined coefficient of thermal expansion that is substantially matched to the material coefficient of thermal expansion.
9. The string as defined by claim 1 wherein the exposed layer is thinner than the refractory layer.
10. The string as defined by claim 1 wherein the string has a coefficient of thermal expansion that is generally matched to the coefficient of thermal expansion of polysilicon.
11. A string for use in a string ribbon crystal, the string comprising:
a base portion comprising a refractory material; and
an externally exposed layer radially outward of the refractory material, the base portion having a coefficient of thermal expansion that is generally matched with the coefficient of thermal expansion for silicon, the externally exposed layer having a contact angle with silicon of between about 15 and 120 degrees.
12. The string as defined by claim 11 wherein the base portion comprises a carbon-based substrate supporting a silicon carbide refractory layer.
13. The string as defined by claim 11 wherein the externally exposed layer comprises a handling layer.
14. The string as defined by claim 11 wherein the externally exposed layer comprises a least one of carbon, carbide, oxide, and nitride.
15. A ribbon crystal comprising:
a string having a string coefficient of thermal expansion and an outer surface; and
a body comprising a body material having a body coefficient of thermal expansion that is generally matched to the string coefficient of thermal expansion,
the string outer surface being partially exposed.
16. The ribbon crystal as defined by claim 15 wherein the exposed portion of the string is free of body material.
17. The ribbon crystal as defined by claim 15 wherein the string outer surface has a contact angle with the body material of between about 15 and 120 degrees.
18. The ribbon crystal as defined by claim 15 wherein the body material comprises polysilicon.
19. The ribbon crystal as defined by claim 15 wherein the string comprises a refractory material supported on and substantially entirely covering a substrate.
20. The ribbon crystal as defined by claim 15 wherein the string comprises a substrate supporting a refractory layer, the string further comprising a handling layer radially outward of the refractory layer, the handling layer applying a generally radially inward force to the refractory layer.
21. The ribbon crystal as defined by claim 20 wherein the handling layer includes the string outer surface.
22. The ribbon crystal as defined by claim 20 wherein the string outer surface is radially outward of the handling layer.
23. The ribbon crystal as defined by claim 15 wherein the string outer surface comprises at least one of pyrolytic carbon, oxide, and nitride.
24. The ribbon crystal as defined by claim 15 wherein the string outer surface has a contact angle with the body material of greater than about 25 degrees.
25. A method of forming a string for use with a ribbon crystal, the method comprising:
forming a refractory layer on a substrate; and
applying a reduced wetting material radially outward of the refractory layer, the reduced wetting material having a contact angle with silicon of between about 15 and 120 degrees.
26. The method as defined by claim 25 further comprising adding a handling layer radially outward of the refractory layer.
27. The method as defined by claim 26 wherein the handling layer comprises the reduced wetting material.
28. The method as defined by claim 26 wherein the reduced wetting material is radially outward of the handling layer.
29. The method as defined by claim 25 wherein forming comprises extruding refractory material on the substrate.
30. The method as defined by claim 25 wherein the refractory layer, substrate, and reduced wetting material have a combined coefficient of thermal expansion that substantially matches polysilicon.
31. A method of forming a ribbon crystal, the method comprising:
providing molten material having a material coefficient of thermal expansion;
providing a string having an outer surface with a contact angle with the molten material of between about 15 and 120 degrees, the string also having a string coefficient of thermal expansion that is substantially matched to the material coefficient of thermal expansion; and
passing the string through molten material to form a sheet.
32. The method as defined by claim 31 wherein the string comprises a refractory layer supported on a substrate.
33. The method as defined by claim 32 wherein the string comprises a handling layer radially outward of the refractory layer.
34. The method as defined by claim 33 wherein the outer surface of the string comprises the handling layer.
35. The method as defined by claim 33 wherein the string comprises a reduced wetting layer radially outward of the handling layer, the reduced wetting layer comprising the outer surface of the string.
36. The method as defined by claim 31 wherein the material comprises a silicon based material.

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 method, comprising:
introducing a cleaning gas to a processing chamber;
applying an electrical bias to a gas distribution showerhead that is coupled to the processing chamber while a substrate support disposed opposite the showerhead is electrically floating or grounded, the showerhead having a showerhead body comprising stainless steel having a roughened surface with a ceramic coating thereover facing the substrate support, the ceramic coating deposited on the roughened surface while controlling deposition pressure to form a desired roughness, the showerhead body having a plurality of first gas passages and a plurality of second gas passages extending therethrough, the electrical bias igniting the cleaning gas into a plasma containing cleaning gas radicals and ions;
reacting the cleaning gas radicals with deposits formed on the ceramic coating by bombarding the ceramic coating with the cleaning gas radicals to form a byproduct and expose the ceramic coating, the exposed ceramic coating having an emissivity within 2 percent of the emissivity of the ceramic coating prior to formation of the deposits thereon; and
exhausting the byproduct from the processing chamber.
2. The method of claim 1, wherein the cleaning gas comprises a chlorine containing gas.
3. The method of claim 2, wherein the chlorine containing gas is selected from the group consisting of Cl2, ICl, HCl, BCl3, CCl4, CH3Cl and combinations thereof.
4. The method of claim 3, wherein the electrical bias is a negative electrical bias.
5. The method of claim 4, wherein the pressure within the chamber during the cleaning is less than about 300 mTorr.
6. The method of claim 5, wherein the electrical bias is between about 2.23 Win2 to about 16 Win2.
7. A method, comprising:
performing a deposition process on one or more substrates in a processing chamber while changing the emissivity of a gas distribution showerhead from a first emissivity level to a second emissivity level;
removing the substrates from the processing chamber;
introducing a cleaning gas to a processing chamber;
applying an electrical bias to the gas distribution showerhead that is coupled to the processing chamber while a substrate support disposed opposite the showerhead is electrically floated or grounded, the showerhead having a showerhead body comprising stainless steel having a roughened surface and a ceramic coating thereover facing the substrate support, the ceramic coating deposited on the roughened surface while controlling deposition pressure to form a desired roughness, the showerhead body having a plurality of first gas passages and a plurality of second gas passages extending therethrough, the electrical bias igniting the cleaning gas into a plasma containing cleaning gas radicals and ions;
reacting the cleaning gas radicals with deposits formed on the ceramic coating by bombarding the ceramic coating with the cleaning gas radicals to form a byproduct and expose the ceramic coating, the exposed ceramic coating having a third emissivity level that is within 2 percent of the first emissivity level; and
exhausting the byproduct from the processing chamber.
8. The method of claim 7, wherein the cleaning gas comprises a chlorine containing gas.
9. The method of claim 8, wherein the chlorine containing gas is selected from the group consisting of Cl2, ICl, HCl, BCl3, CCl4, CH3Cl and combinations thereof.
10. The method of claim 9, wherein the electrical bias is a negative electrical bias.
11. The method of claim 10, wherein the deposition process is a MOCVD process.
12. The method of claim 11, further comprising performing another deposition process on one or more additional substrates after exhausting the byproduct.
13. The method of claim 1, wherein the cleaning occurs in-situ.