Abstract: An electromagnetic device includes a jig and multiple wires. The jig includes a center member and coil-separating blocks. The coil-separating blocks protrude from the center member and are separated from each other to provide a coil channels. Each of the wires is wrapped on the jig, around the center member, and in one of the coil channels to form one of a multiple coils. Each of the coils is configured to connect to an electromagnetic navigation system and generate respective electromagnetic fields to be emitted relative to a subject.

Abstract: Apparatus and methods are disclosed for measuring the surface topography of a test surface, such as a spherical or aspherical surface of a refractive or reflective optical element. The test surface is measured by detecting the state of interference fringes generated by interference of a reference light beam and a measurement light beam that interacts (e.g., reflects from) the test surface. The reference and measurement beams are produced by a point light source having a reflective surface. The point light source is disposed between a source of input light and the test surface. The measurement beam (after interacting with the test surface) and the reference beam are caused to interfere with each other to produce a first interference-fringe state. The distance between the point light source and the test surface can be changed between production of the first interference-fringe state and production of a second interference-fringe state.