194 results about "Magnetic lens" patented technology

The present invention illustrates various methods of attaching a pair of eyeglass lenses or a lens shield to an eyeglass frame using magnets or magnetically attractive material. The magnetic attachment methods are beneficial because they allow the user to have interchangeable lenses or shields for indoor and outdoor use, enhancing their visual acuity during work or play. The lenses may be tinted, prescription, protective eyewear, or plano. The magnetic lenses are convenient and user friendly, allowing intuitive, tool-less interchangeability with no need to twist or stress the frame. These methods of attachment require no specific instructions or tools when the user replaces lenses.

An apparatus basically uses a simple and compact multi-axis magnetic lens to focus each of a plurality of charged particle beams on sample surface at the same time. In each sub-lens module of the multi-axis magnetic lens, two magnetic rings are respectively inserted into upper and lower holes with non-magnetic radial gap. Each gap size is small enough to keep a sufficient magnetic coupling and large enough to get a sufficient axial symmetry of magnetic scale potential distribution in the space near to its optical axis. This method eliminates the non-axisymmetric transverse field in each sub-lens and the round lens field difference among all sub-lenses at the same time; both exist inherently in a conventional multi-axis magnetic lens. In the apparatus, some additional magnetic shielding measures such as magnetic shielding tubes, plates and house are used to eliminate the non-axisymmetric transverse field on the charged particle path from each charged particle source to the entrance of each sub-lens and from the exit of each sub-lens to the sample surface.

A magnetic lens configured to apply a magnetic field to a charged particle beam is provided. The magnetic lens may include an outer pole piece and an inner pole piece. The outer pole piece may have at least two sectors and at least two slots. The magnetic lens may also have a primary coil winding interposed between the outer pole piece and the inner pole piece. In addition, the magnetic lens may have a number of sector coil windings, and each sector of the outer pole piece may be coupled to one sector coil winding. A magnetic potential of the outer pole piece relative to the inner pole piece may be generated by applying a current to the primary coil winding. A separate magnetic potential of each sector may also be generated by applying a current to the respective sector coil windings of each sector of the outer pole piece.

Disclosed are lens apparatus in which a beam of charged particles is brought to a focus by means of a magnetic field, the lens being situated behind the target position. In illustrative embodiments, a lens apparatus is employed in a scanning electron microscope as the sole lens for high-resolution focusing of an electron beam, and in particular, an electron beam having an accelerating voltage of from about 10 to about 30,000 V. In one embodiment, the lens apparatus comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. In other embodiments, the lens apparatus comprises a magnetic dipole or virtual magnetic monopole fabricated from a variety of materials, including permanent magnets, superconducting coils, and magnetizable spheres and needles contained within an energy-conducting coil. Multiple-array lens apparatus are also disclosed for simultaneous and / or consecutive imaging of multiple images on single or multiple specimens. The invention further provides apparatus, methods, and devices useful in focusing charged particle beams for lithographic processes.

An electron beam apparatus and method are presented for collecting side-view and plane-view SEM imagery. The electron beam apparatus includes an electron source, some intermediate lenses if needed, an objective lens and an in-lens sectional detector. The electron source will provide an electron beam. The intermediate lenses focus the electron beam further. The objective lens is a combination of an immersion magnetic lens and a retarding electrostatic lens focuses the electron beam onto the specimen surface. The in-lens detector will be divided into two or more sections to collect secondary electrons emanating from the specimen with different azimuth and polar angle so that side-view SEM imagery can be obtained.

In one embodiment of the present invention, a magnetic lens is provided that can generate a substantially constant amount of average heat power over a pre-selected range of resultant magnetic field strengths. The lens is configured to do this with multiple, asymmetric (different turns) coil sections that can produce a desired range of field strengths, and at the same time, maintain a sufficiently constant temperature signature when the average total power is maintained constant thereby eliminating unreasonable delays in lens operation when the resultant field strength is changed. The asymmetric lens structure allows for the smaller coil to be made with less relative inductance thereby making it more responsive and amenable for an AC drive signal and thus dynamic focusing applications if desired. Thus, a magnetic lens is now provided that can produce a range of magnetic beam-focusing field strengths, implement dynamic focusing, and not impose unreasonable delay for thermal stabilization between changes in magnetic field strength.

An improved induction tool for evaluating formation resistivity. The tool provides electromagnetic transmitters and sensors suitable for transmitting and receiving magnetic fields in radial directions that are orthogonal to the tool's longitudinal axis with minimal susceptibility to errors associated with parasitic eddy currents induced in the metal components surrounding the transmitter and receiver coils. A magnetic lens is provided to select sensitivity to a desired reservoir formation property.

An apparatus basically uses a simple and compact multi-axis magnetic lens to focus each of a plurality of charged particle beams on sample surface at the same time. In each sub-lens module of the multi-axis magnetic lens, two magnetic rings are respectively inserted into upper and lower holes with non-magnetic radial gap. Each gap size is small enough to keep a sufficient magnetic coupling and large enough to get a sufficient axial symmetry of magnetic scale potential distribution in the space near to its optical axis. This method eliminates the non-axisymmetric transverse field in each sub-lens and the round lens field difference among all sub-lenses at the same time; both exist inherently in a conventional multi-axis magnetic lens. In the apparatus, some additional magnetic shielding measures such as magnetic shielding tubes, plates and house are used to eliminate the non-axisymmetric transverse field on the charged particle path from each charged particle source to the entrance of each sub-lens and from the exit of each sub-lens to the sample surface.