Ion lens system for mass spectrometers and method of operation

Claim 2

In a mass spectrometer an ionization source for ionizing a sample to be analyzed, said source having an ion exit slit for the passage of a beam of ions, analyzer means disposed to apply a deflection field to a said beam of ions, and detection means positioned to receive at least a portion of the ions in said beam of ions in order to analyze said ions, wherein the improvement comprises: an ion lens system disposed between said ion exit slit and the entire analyzer means and including; first and a second electrostatic lens means each having an aperture therein for the passage of a said beam of ions, said first and second electrostatic lens means disposed between said ion exit slit and the entire analyzer means to form a focused image of said ion exit slit in a focal plane between said lens means and said analyzer means; control means for varying the focal lengths of said first and second electrostatic lens means in a manner to vary the width of a said image of said slit in a said focal plane while maintaining the image focus in the plane whereby the lens means function in the manner of an adjustable slit.

Claim 3

An apparatus as defined in claim 1 wherein said first electrostatic lens means includes first, second, and third apertured members positioned in spaced relationship with respect to each other, said first and third apertured members being connected to ground potential.

Claim 4

An apparatus as defined in claim 1 wherein each of said first and second electrostatic lens means comprises first, second and third apertured members positioned in spaced relationship with respect to each other, each of said first and third apertured members being coupled to a constant source of potential and the second apertured members of said first and second electrostatic lens means being coupled to variable sources of potential.

Claim 5

An apparatus as defined in claim 1 including a second ion lens system disposed between the entire analyzer means and said detection means and including; first and second electrostaitc lens means each having an aperture therein for the passage of a said beam of ions, said first and second electrostatic lens means disposed between said ion exit slit and said detection means to thereby form an image of said ion exit slit in a second plane between said lens means and said detection means; control means for varying the focal lengths of said first and second electrostatic lens means in a manner to vary the width of a said image of said ion exit slit in a said second plane.

Claim 8

A method of varying the width of an ion beam as set forth in claim 5 including the steps of: applying first and second potential signals respectively to a first and a second apertured member in said first electrostatic lens means; applying third and fourth potential signals respectively to a first and a second apertured member in said second electrostatic lens means; and, varying the value of both of said first and third potential signals in order to vary the width of the ion beam by changing the focal lengths of both the first and second electrostatic lenses while maintaining the focal length of the beam substantially constant.

Claim 9

In a mass spectrometer including an ionization source for ionizing a sample to be analyzed, said source having an ion exit slit to pass a beam of ions from the ionization source, analyzer means, detection means positioned to receive at least a portion of the ions in said beam of ions after passage through said analyzer means, and an ion collector slit disposed between said analyzer means and said detection means wherein the improvement comprises: an ion lens system disposed between one of said ion slits and the entire analyzer means and including; first and second electrostatic lens means each having an aperture therein for the passage of a said beam of ions; said first electrostatic lens means disposed such that this lens means provides a first image in a cross over plane situated between said first electrostatic lens means and one side of said second electrostatic lens means, and said second electrostatic lens means disposed such that this lens means provides a second image in a focal plane which is positioned on the opposite side of said second electrostatic lens means; and, control means for varying the focal length of both said first and second lens means in a manner such that the location of the cross over plane is shifted longitudinally of the beam while the image plane of the second image is at a constant position to thereby vary the magnification of said ion lens system whereby to cause the lens means to function in the manner of an adjustable slit.

Claim 10

In a mass spectrometer including an ionization source for ionizing a sample to be analyzed, said source having an ion exit slit to pass a beam of ions from the ionization source, analyzer means, detection means positioned to receive at least a portion of the ions in said beam of ions after passage through said analyzer means, and an ion collector slit disposed between said analyzer means and said detection means wherein the improvement comprises: an ion lens system disposed between one of said ion slits and the entire analyzer means and including; first and second electrostatic lens means each having an aperture therein for the passage of a said beam of ions; said first electrostatic lens means disposed such that this lens means provides a first image in a cross over plane situated between said first electrostatic lens means and one side of said second electrostatic lens means, and said second electrostatic lens means disposed such that this lens means provides a second image in a focal plane which is positioned on the opposite side of said second electrostatic lens means; and, control means for varying the focal length of both said first and second lens means in a manner such that the location of the cross over plane is shifted longitudinally of the beam while the image plane of the second image is at a constant position to thereby vary the magnification of said ion lens system whereby to cause the lens means to function in the manner of an adjustable slit.

Claim 11

An apparatus as defined in claim 7 wherein said one ion slit is said ion exit slit of said ionization source.

Claim 12

An apparatus as defined in claim 8 including a second ion lens system disposed between said analyzer means and said detection means and including: third and fourth lens means each having an aperture therein for the passage of a said beam of ions and for forming a third image in a third plane between said second lens system and said detection means; and, control means for varying the focal lengths of said third and fourth lens means in a manner such that the plane of the third image is at a constant position to thereby vary the magnification of said ion lens system.

Claim 13

An apparatus as defined in claim 7 wherein said one ion slit is said ion collector slit.

Claim 14

In a double focusing mass spectrometer an ionization source for ionizing a sample to be analyzed, said source having an ion exit slit for the passage of a beam of ions, double focusing analyzer means including an electrostatic analyzer disposed to apply an electrostatic deflection field to a said beam of ions and a magnetic analyzer disposed to apply a magnetic deflection field to a said beam of ions, detection means positioned to receive at least a portion of the ions in said beam of ions after passage through said double focusing analyzer means, and an ion collector slit disposed between said double focusing analyzer means and said detector means wherein the improvement comprises: an ion lens system disposed between one of said ion slits and said double focusing analyzer means and including; first and second elEctrostatic lens means each having an aperture therein for the passage of a said beam of ions, said first and second electrostatic lens means disposed between one of said ion slits and said double focusing analyzer means to thereby form an image in an image plane; control means for varying the focal lengths of said first and second electrostatic lens means in a manner to vary the width of said image in said image plane while maintaining the overall focal length of said lens system substantially constant whereby the lens system functions in the manner of an adjustable slit.

Claim 15

In a double focusing mass spectrometer an ionization source for ionizing a sample to be analyzed, said source having an ion exit slit for the passage of a beam of ions, double focusing analyzer means including an electrostatic analyzer disposed to apply an electrostatic deflection field to a said beam of ions and a magnetic analyzer disposed to apply a magnetic deflection field to a said beam of ions, detection means positioned to receive at least a portion of the ions in said beam of ions after passage through said double focusing analyzer means, and an ion collector slit disposed between said double focusing analyzer means and said detector means wherein the improvement comprises: an ion lens system disposed between one of said ion slits and said double focusing analyzer means and including; first and second elEctrostatic lens means each having an aperture therein for the passage of a said beam of ions, said first and second electrostatic lens means disposed between one of said ion slits and said double focusing analyzer means to thereby form an image in an image plane; control means for varying the focal lengths of said first and second electrostatic lens means in a manner to vary the width of said image in said image plane while maintaining the overall focal length of said lens system substantially constant whereby the lens system functions in the manner of an adjustable slit.

Claim 16

An apparatus as defined in claim 11 wherein said one ion slit is said ion exit slit of said ionization source.

Claim 17

An apparatus as defined in claim 12 including a second ion lens system disposed between said analyzer means and said detection means and including: third and fourth electrostatic lens means each having an aperture therein for the passage of a said beam of ions, said third and fourth electrostatic lens means disposed between said analyzer means and said detection means to thereby form a second image in a second plane between said third and fourth lens means and said detection means; control means for varying the focal lengths of said third and fourth electrostatic lens means in a manner to vary the width of said second image in said second plane while said second image plane remains at a constant position.

Claim 18

An apparatus as defined in claim 11 wherein said one ion slit is said ion collector slit.

Claim 19

In a double focusing mass spectrometer including an ionization source for ionizing a sample to be analyzed, said source having an ion exit slit to pass a beam of ions from the ionization source, double focusing analyzer means including an electrostatic analyzer disposed to apply an electrostatic deflection field to a said beam of ions and a magnetic analyzer disposed to apply a magnetic deflection field to a said beam of ions, detection means positioned to receive at least a portion of the ions in said beam of ions after passage through said double focusing analyzer means, and an ion collector slit disposed between said double focusing analyzer means and said detector means wherein the improvement comprises: an ion lens system disposed between one of said ion slits and said double focusing analyzer means and including; first and second electrostatic lens means each having an aperture therein for the passage of a beam of ions; said first electrostatic lens means disposed such that this lens means provides a first image in a cross over plane situated between said first electrostatic lens means and said second electrostatic lens means, and said second electrostatic lens means disposed such that this lens means provides a second image in an image plane; and, control means for varying the focal length of both said first and second electrostatic lens means while maintaining the total focal length of both of said electrostatic lens means substantially constant to thereby vary the magnification of said ion lens system in the image plane whereby the lens system functions in the manner of an adjustable slit.

Claim 20

In a double focusing mass spectrometer including an ionization source for ionizing a sample to be analyzed, said source having an ion exit slit to pass a beam of ions from the ionization source, double focusing analyzer means including an electrostatic analyzer disposed to apply an electrostatic deflection field to a said beam of ions and a magnetic analyzer disposed to apply a magnetic deflection field to a said beam of ions, detection means positioned to receive at least a portion of the ions in said beam of ions after passage through said double focusing analyzer means, and an ion collector slit disposed between said double focusing analyzer means and said detector means wherein the improvement comprises: an ion lens system disposed between one of said ion slits and said double focusing analyzer means and including; first and second electrostatic lens means each having an aperture therein for the passage of a beam of ions; said first electrostatic lens means disposed such that this lens means provides a first image in a cross over plane situated between said first electrostatic lens means and said second electrostatic lens means, and said second electrostatic lens means disposed such that this lens means provides a second image in an image plane; and, control means for varying the focal length of both said first and second electrostatic lens means while maintaining the total focal length of both of said electrostatic lens means substantially constant to thereby vary the magnification of said ion lens system in the image plane whereby the lens system functions in the manner of an adjustable slit.

Claim 21

An apparatus as defined in claim 15 wherein said one ion slit is said ion exit of said ionization source.

Claim 22

An apparatus as defined in claim 16 including a second ion lens system disposed between said analyzer means and said detection means and including: third and fourth electrostatic lens means each having an aperture therein for the passage of a said beam of ions, said first and second electrostatic lens means disposed between said analyzer means and said detection means to thereby form an image in a second image plane between said third and fourth lens means and said detection means; control means for varying the focal lengths of said third and fourth electrostatic lens means in a manner to vary the width of said image in said second image plane.

Claim 23

An apparatus as defined in claim 15 wherein said one ion slit is said ion colleCtor slit.

Claim 24

In a mass spectrometer an ionization source for ionizing a sample to be analyzed, said source having an ion exit slit for the passage of a beam of ions, analyzer means, detection means positioned to receive at least a portion of the ions in said beam of ions after passage through said analyzer means, and an ion collector slit disposed between said analyzer means and said detector means wherein the improvement comprises: a. a first ion lens system disposed between said ion exit slit and the analyzer means and including: i. first and second lens means each having an aperture therein for the passage of a said beam of ions and for forming an image in an image plane; ii. control means for varying the focal lengths of said first and second lens means in a manner to vary the width of said image in said image plane while maintaining the focal length of said beam substantially constant; b. a second ion lens system disposed between said analyzer means and said detection means and including: i. third and fourth lens means each having an aperture therein for the passage of a said beam of ions and for forming a second image in a second image plane between said third and fourth lens means and said detection means; and, ii. control means for varying the focal lengths of said third and fourth lens means in a manner to vary the width of said second image in said second image plane while maintaining the focal length of said beam substantially constant.

Claim 25

In a mass spectrometer an ionization source for ionizing a sample to be analyzed, said source having an ion exit slit for the passage of a beam of ions, analyzer means, detection means positioned to receive at least a portion of the ions in said beam of ions after passage through said analyzer means, and an ion collector slit disposed between said analyzer means and said detector means wherein the improvement comprises: a. a first ion lens system disposed between said ion exit slit and the analyzer means and including: i. first and second lens means each having an aperture therein for the passage of a said beam of ions and for forming an image in an image plane; ii. control means for varying the focal lengths of said first and second lens means in a manner to vary the width of said image in said image plane while maintaining the focal length of said beam substantially constant; b. a second ion lens system disposed between said analyzer means and said detection means and including: i. third and fourth lens means each having an aperture therein for the passage of a said beam of ions and for forming a second image in a second image plane between said third and fourth lens means and said detection means; and, ii. control means for varying the focal lengths of said third and fourth lens means in a manner to vary the width of said second image in said second image plane while maintaining the focal length of said beam substantially constant.