A precision laser pattern generator for writing arbitrary diffractive elements was developed as an alternative to Cartesian coordinate laser/electron-beam writers. This system allows for the fabrication of concentric continuous-relief and arbitrary binary patterns with minimum feature sizes of less than 0.6 microm and position accuracy of 0.1 microm over 300-mm substrates. Two resistless technologies of writing on chromium and on amorphous silicon films were developed and implemented. We investigated limit characteristics by writing special test structures. A 58-mm f/1.1 zone plate written directly is demonstrated at a lambda/50 rms wave-front error corresponding to a 0.06-microm pattern accuracy. Several examples of fabricated diffractive elements are presented.

A diffractive optical element has been synthesized with laser phototechnology. It can transform a point source into a bright caustic (a light line) stretched along the optical axis. The element transforms a spherical wave into a conic and a point source in the object space to a ring structure in the image space. We investigated how the parameters of the light line (the length and the effective diameter) depend on the wavelength of the light source and the movement of the source along the optical axis. Also the interference field outside the caustic (Fresnel and Poisson fringes) was investigated. For an explanation of experimental data the geometrical theory of interferometers was used. The conditions for the appearance of fringes in white light are given. A device for rectilinear control of large tool beds and for centering machine components was manufactured. Experiments on determining the macroshape and the microshape of objects were performed.

No abstract

No abstract

Natural brown diamonds that emit yellow luminescence under 3.40 eV (365 nm) excitation are known to exhibit also a red luminescence band when excited with 2.69 eV (460 nm) radiation. Four zero-phonon red-luminescent lines have been studied under uniaxial stress. One of them, at 2.145 eV, believed to be the origin of the major vibronic progression known as the red band, is found to be a transition between A states at a monoclinic I centre. The other lines at 2.133,2.156 and 2.166 e V are shown to be transitions between A and B states at monoclinic I1 centres, with the CZ point group. It is the first time that centres with this point group have been reported in diamond. We suggest a relationship between the centres giving rise to the yellow and to the red luminescence bands, by comparison of their phonon sidebands, symmetries, responses to stress and zero-phonon energies.