Jan Gerard Dil

Tandem multipass Fabry-Perot interferometer for Brillouin scattering

A new design of a plane mirror Fabry-Perot interferometer with the mirror blanks freely supported by horizontal rings is described. Special attention is paid to the surface flatness and dielectric coatings of the mirrors. It is shown that any two piezoelectrically scanned Fabry-Perot interferometers can be synchronized in tandem operation using simple optics and standard electronic driving and stabilization equipment. Applications of the tandem system to Brillouin scattering are given. The observation of Brillouin spectra of supported thin plastic films and of a clamped metal surface is reported.

Apparent size of reflecting polygonal obstacles of the order of one wavelength

Rigorous diffraction theory is applied to compute the electromagnetic fields in the neighborhood of polygonal obstacles of three- and two-dimensional shape, including two-dimensional gratings. For obstacles such as a rectangular depression, a polygonal groove, or an array of grooves present in a metallic substrate, we calculate and measure significant departures from what a scalar diffraction approach would predict as soon as the width of the obstacle becomes smaller than one wavelength. For such widths, it is shown that the apparent depth of a groove can be smaller or larger than the geometrical depth, depending on the polarization of the incident light and on the optical constants of the substrate.

Control of pit geometry on video disks

Optical techniques are described for measuring the pit geometry on video disks throughout the process of mastering and replication. Special attention is paid to the determination of the slope and the depth of the pits during their formation in the resist layer during development.

Measurement of steep aspheric surfaces.

A method of measuring the shape of high numerical aperture (NA <0.95), convex or concave, aspheric surfaces is described. The aspheric slope may be as large as 1200 waves/rad. The method is applied in two steps. First, a standard measurement is performed to obtain a reference surface. Second, the reproducibility of the fabrication of aspheric surfaces is tested by means of a holographic comparison method. The measuring error is smaller than 0.1 microm.

High-Precision Measurement Of Aspheric Surfaces

We report the operation of a new instrument which measures with ± 5 nm precision the shape of steep aspheric surfaces. The instrument makes use of contacting probes, and its working is based on an optical differential technique. Special attention is paid to the mechanical construction, and a detailed error analysis is given.