F . Zernike

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This paper gives the details of a precision two-beam scanning Michelson interferometer, designed and perfected for accurate comparison of an unknown laser wavelength and the precisely calibrated wavelength of a reference laser. An iodine Lamb-dip stabilized He-Ne 633-nm laser (calibrated with respect to a Kr standard) is used as the reference. The design(More)
Phase contrast makes living, unstained microscopic structures visible. Normally the difference in refractive index between a living microscopic structure and its surrounding environment is so small that the structure refracts very little light. Light is, however, diffracted by the specimen. Diffracted light is, on average, slowed down by 1/4 of a wavelength(More)
A molybdenum/silicon multilayer-coated 1:1 ring-field optic with a numerical aperture of 0.0835 is used to carry out soft-x-ray projection imaging with undulator radiation at 12.9 nm. An ideal optic of this type should be able to image 0.1-µm features with a contrast exceeding 90% at this wavelength. The useful resolution of our ring-field optic is(More)
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