DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Objections
Claim 1 is objected to because of the following informalities:
In line 7, “in vacuum chamber” should read “in a vacuum chamber”.
Appropriate correction is required.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-3 and 5-22 are rejected under 35 U.S.C. 103 as being unpatentable over Morishita (US 20140361167 A1) in view of Hamamatsu (Hamamatsu Photonics K.K., “Photomultiplier Tube: Basics and Applications”, Fourth Edition, 332 pages (2017)).
Regarding claim 1, Morishita teaches a charged-particle beam (CPB) microscope (electron microscope, figs. 1A-1B), comprising:
A CPB optical system (lens 27, deflectors 10) operable to direct a CPB along a CPB optical system axis towards a sample (specimen 2);
A magnetic lens (4-1) operable to produce a magnetic immersion field (in embodiment of fig. 1B, [0053]) and shape the CPB at the sample, the magnetic lens situated on the CPB optical system axis and including a pole piece (40) that defines a bore (opening in pole piece 40) through which the CPB is directed to the sample;
A CPB detector (9) adapted to be situated in the vacuum chamber containing the CPB optical system (fig. 1A) and that includes;
A scintillator (9-1) situated in the bore of the pole piece and operable to receive charged particles from the sample (fig. 1B) in response to irradiation of the sample with the CPB and produce scintillation light that is directed along a passage defined in the pole piece (passage for light guide 9-2, fig. 1B), and
A photomultiplier tube (PMT) (9-3) situated to receive the scintillation light from the passage in the pole piece.
Morishita does not teach a photocathode for receiving the scintillation light, or a PMT magnetic shield that defines a cavity that receives the PMT and a first aperture situated so that the PMT photocathode receives the scintillation light through the first aperture in the PMT magnetic shield.
Hamamatsu teaches that PMTs typically have photocathodes for receiving light (p. 14, 2.1 “Structures and Multiplication Principles of Photomultiplier Tubes”) and magnetic shields (p. 131, 5.4.3 “Magnetic Shield”) that defines a cavity and an aperture for receiving light (e.g. cylindrical magnetic shield, fig. 5-68).
It would have been obvious to one of ordinary skill in the art on or before the effective filing date of the invention to modify the system of Morishita to have the photocathode of Hamamatsu (which is a known element of a photomultiplier tube necessary to convert photons to electrons) and to have the magnetic shield of Hamamatsu, in order to prevent magnetic interference from stray electric fields with the electron trajectories in the PMT.
Regarding claim 2, Morishita teaches that the pole piece has a conical taper so that the diameter of the pole piece decreases along the CPB optical axis towards the sample (fig. 1B). Placing the magnetic shield of Hamamatsu around the PMT of Morishita would result in the magnetic shield being proximate the pole piece.
Morishita and Hamamatsu do not teach that the magnetic shield is in a volume bounded by a conical surface of the pole piece.
It would have been obvious to one of ordinary skill in the art on or before the effective filing date of the invention to adjust the size and position of the magnetic shield to be within the pole piece of Morishita, since Hamamatsu teaches that it is effective to place the PMT deep within the magnetic shield (p. 136 bottom paragraph, fig. 5-76) and the long portion of the magnetic shield surrounding the light guide (9-2) of Morishita could easily extend into the pole piece 40, as a matter of arranging the parts of the invention with no unexpected result (MPEP 2144.04 VI C [R-01 2024]).
Regarding claim 3, Hamamatsu teaches that the PMT magnetic shield is formed of a nickel-iron alloy (Permalloy, p. 131 last paragraph).
Regarding claim 5, Morishita teaches that the passage defined in the pole piece extends to apertures that are oppositely situated on a conical surface of the pole piece (apertures may be provided with four-fold symmetry around the pole piece, [0062]).
Regarding claim 6, Morishita teaches that the CPB detector includes a lightguide (9-2) optically coupled to the scintillator and the PMT to direct the scintillation light into the PMT, wherein the lightguide extends at least in part along the passage defined in the pole piece towards the PMT (fig. 1B).
Regarding claim 7, Hamamatsu teaches that the cavity defined by the PMT magnetic shield has a circular cross-section (fig. 5-68, p. 132).
Regarding claim 8, Hamamatsu teaches that the PMT is a head-on PMT and the PMT magnetic shield extends from a PMT faceplate to a distal end of a PMT base (p. 138, fig. 5-78).
Regarding claim 9, Hamamatsu teaches that the PMT magnetic shield includes a portion situated along a PMT envelope (portion surrounding PMT, fig. 5-78) and a portion situated at the PMT faceplate (portion extending beyond front of PMT, fig. 5-78), the portion situated at the PMT faceplate defining an aperture (which in the combination with Morishita, receives the scintillation light and transmits the scintillation light to the PMT photocathode.
Regarding claim 10, it would have been obvious to one of ordinary skill in the art on or before the effective filing date of the invention to fix the magnetic shield of Hamamatsu to the pole piece of Morishita, as it has been held that making the parts of the invention integral with each other is within the skill of one of ordinary skill in the art (MPEP 2144.04 V B [R-01.2024]). In this case one of ordinary skill in the art could easily fasten the magnetic shield in place by any suitable means, e.g. screws, for the purpose of keeping it in a fixed position, with little to no functional effect on the invention.
Regarding claim 11, Hamamatsu teaches a casing situated about at least a portion of the PMT magnetic shield (fig. 5-78).
Hamamatsu does not teach that the casing is made from a non-ferromagnetic material.
It would have been obvious to one of ordinary skill in the art at the time of the invention to make the casing of Hamamatsu from a non-ferromagnetic material, as a matter of selecting a known material for its suitability for an intended purpose (MPEP 2144.07 [R-01.2024]). In this case the casing can be made of any material, e.g. plastic, with no unexpected result.
Morishita and Hamamatsu do not teach that the casing is fixed to the pole piece.
It would have been obvious to one of ordinary skill in the art on or before the effective filing date of the invention to fix the casing of Hamamatsu to the pole piece of Morishita, as it has been held that making the parts of the invention integral with each other is within the skill of one of ordinary skill in the art (MPEP 2144.04 V B [R-01.2024]). In this case one of ordinary skill in the art could easily fasten the casing in place by any suitable means, for the purpose of keeping it in a fixed position, with little to no functional effect on the invention.
Regarding claim 12, Hamamatsu teaches that the PMT may be a side-on PMT and the magnetic shield surrounds the PMT envelope and at least a portion of a PMT base (Fig. 5-79, p. 138).
Regarding claim 13, Morishita and Hamamatsu do not teach that the magnetic shield is operable to reduce a magnetic field of at least 0.1 T at a PMT location by a factor of at least 20.
However, Hamamatsu teaches that the magnetic shield can reduce a magnetic field by a factor of 1000 (p. 136, fig. 5-76). While Hamamatsu teaches a smaller external magnetic field (3 mT, p. 133), it would be obvious to one of ordinary skill in the art that the system could be adjusted for stronger magnetic fields by increasing the thickness of the magnetic shielding, as a matter of routine optimization with no unexpected result.)
Regarding claim 14, Morishita teaches that the scintillator defines a CPB transmissive aperture on the CPB axis and is optically face coupled to the light guide to direct the scintillation light to the PMT photocathode (fig. 1-B).
Regarding claim 15, Hamamatsu teaches that the cavity defined by the PMT magnetic shield includes a portion that extends beyond the PMT as situated in the cavity at least at one end by a distance that is greater than or equal to a PMT diameter (fig. 5-76).
Regarding claim 16, Hamamatsu teaches that the PMT magnetic shield surrounds the PMT as situated in the cavity and defines a second aperture through which the PMT is electrically coupled (fig. 5-78, electronics connected through socket assembly of casing).
Regarding claim 17, Morishita teaches a method, comprising:
Situating a photomultiplier (9-3) proximate a pole piece (40) of a magnetic lens to receive scintillation light (from scintillator 45) responsive to a charged-particle beam incident to a sample (specimen 2).
Morishita does not teach providing a PMT magnetic shield about at least a portion of the PMT to reduce a magnetic field associated with the magnetic lens at the PMT by at least a factor of 20 for magnetic field strengths of at least 0.1 T.
Hamamatsu teaches a PMT having a magnetic shield (p. 131, 5.4.3 “Magnetic Shield”) that can reduce a magnetic field by a factor of 1000 (p. 136, fig. 5-76).
It would have been obvious to one of ordinary skill in the art on or before the effective filing date of the invention to modify the system of Morishita to have the magnetic shield of Hamamatsu, in order to prevent magnetic interference from stray electric fields with the electron trajectories in the PMT. (While Hamamatsu teaches a smaller external magnetic field, it would be obvious to one of ordinary skill in the art that the system could be adjusted for stronger magnetic fields by increasing the thickness of the magnetic shielding, as a matter of routine optimization with no unexpected result.)
Regarding claim 18, Morishita teaches that the scintillation light is directed through a passage defined in the pole piece to the PMT, the passage terminating at an aperture in a conical surface of the pole piece (aperture for light guide 9-2, fig. 1B).
Regarding claim 19, Morishita teaches situating a scintillator (9-1) within the bore of the pole piece to produce the scintillation light; and
Coupling the scintillation light through the passage with a lightguide (9-2) that is optically coupled to the scintillator.
Regarding claim 20, Morishita teaches that the extends through the pole piece to form opposing apertures about a CPB optical axis (apertures may be provided with four-fold symmetry around the pole piece, [0062]).
Regarding claim 21, Morishita teaches a charged-particle beam detector situatable in a vacuum chamber of a charged-particle microscope and in a magnetic immersion field of a magnetic objective lens, the CPB detector comprising:
A photomultiplier tube (PMT, 9-3); and
A scintillator (9-1) operable to produce scintillation light in response to charged particles associated with a CPB of the charged-particle microscope.
Morishita does not teach a PMT magnetic shield defining a cavity configured to contain a PMT envelope and at least a portion of a PMT base, the PMT shield formed of a high saturation magnetic material.
Hamamatsu teaches a PMT having a magnetic shield (p. 131, 5.4.3 “Magnetic Shield”) defining a cavity configured to contain a PMT envelope and at least a portion of the PMT base, the PMT shield formed of a high saturation magnetic material (permalloy, p. 132).
It would have been obvious to one of ordinary skill in the art on or before the effective filing date of the invention to modify the system of Morishita to have the magnetic shield of Hamamatsu, in order to prevent magnetic interference from stray electric fields with the electron trajectories in the PMT.
Regarding claim 22, Hamamatsu teaches a PMT having a magnetic shield (p. 131, 5.4.3 “Magnetic Shield”) that can reduce a magnetic field by a factor of 1000 (p. 136, fig. 5-76).
It would have been obvious to one of ordinary skill in the art on or before the effective filing date of the invention to modify the system of Morishita to have the magnetic shield of Hamamatsu, in order to prevent magnetic interference from stray electric fields with the electron trajectories in the PMT. (While Hamamatsu teaches a smaller external magnetic field, it would be obvious to one of ordinary skill in the art that the system could be adjusted for stronger magnetic fields by increasing the thickness of the magnetic shielding, as a matter of routine optimization with no unexpected result.)
Claims 4 is rejected under 35 U.S.C. 103 as being unpatentable over Morishita in view of Hamamatsu and in further view of Jang (US 20230411841 A1).
Regarding claim 4, Morishita and Hamamatsu teach all the limitations of claim 1 as described above. Morishita and Hamamatsu do not teach that the magnetic shield is formed of a magnetic material having a saturation field of at least 0.5 T.
Jang teaches a magnetic shielding material having a saturation of at least 0.5 T (1.2 T, [0052]).
It would have been obvious to one of ordinary skill in the art on or before the effective filing date of the invention to select the material of the magnetic shield in the system of Morishita and Hamamatsu to be that taught by Jang, as a matter of selecting a known material based on its art-recognized suitability for magnetic shielding with no unexpected result (MPEP 2144.07 [R-01.2024]).
Conclusion
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/DAVID E SMITH/Examiner, Art Unit 2881
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