Now showing 1 - 3 of 3
- PublicationDiffractive beam splitter for laser Doppler velocimetryA miniaturized sensor head for the optical measurement of velocities of fluids based on laser Doppler velocimetry is demonstrated. Holographic optical elements mounted on a glass substrate are used for beam splitting and deflection. Volume holograms in dichromated gelatin exhibit good optical efficiency (75% transmission of a cascade of two holographic optical elements). With diffractive devices one can achieve achromatic behavior that makes the sensor insensitive to wavelength drifts or mode hopping of a semiconductor laser.
Scopus© Citations 45 527
- PublicationBinary blazed reflection gratingsA reflection grating with a binary surface profile is presented that has high diffraction efficiency. The measured intensity for the + 1st diffracted order was 77%. The binary grating is composed of a minilattice with feature sizes comparable with the wavelength of the incident light. The overall structure is designed in such a way that it imitates a conventional blazed grating. The grating also has interesting polarization properties. The main part of the TE-polarized light is diffracted into the 1st diffracted order, and most of the TM-polarized light remains in the 0th diffracted order. The measurements of the grating are compared with rigorous diffraction theory and found to be in reasonable agreement.
817Scopus© Citations 1
- PublicationInterferometric resolution examined by means of electromagnetic theoryInterferometric methods are widely used in surface metrology. A question that arises is how much information about the surface can be extracted from a given interferogram. For examination of the resolution limit of interferometry with coherent monochromatic light, interferograms of several surface relief gratings calculated with the use of approximate and rigorous theories are presented. The limits of the usefulness of scalar theory based on the use of the Fourier transform are indicated. Interferograms of dielectric and metallic structures are examined, including simple lamellar gratings and gratings made up of trapezoidal steps with varying slopes and depths. In all cases TE illumination is assumed. The effects of changing numerical aperture and defocus on the interferograms are also examined.
378Scopus© Citations 11