Vincenzo Greco

Accurate polarization interferometer

A polarization interferometer which measures optical path differences with improved accuracy control is presented. The approach makes use of four signals in quadrature, computing the phase with an algorithm insensitive to laser power drifts. Experimental results of the interferometer’s performance are given under laser warmup conditions, and with long‐term monitoring of optical path differences.

Absolute measurement of planarity with Fritz's method: uncertainty evaluation.

Fritzs method [Opt. Eng. 23, 379 (1984)] of using Zernike polynomials to assess the absolute planarity of test plates is revisited. A refinement is described that takes into account the data decorrelation that appears in experiments. An uncertainty balance is defined by propagation of error contributions through the steps of the method. The resultant measuring procedure is demonstrated on a data set from experiments, and a nanometer level of uncertainty is achieved.

Telescopes of galileo.

The Florentine Istituto e Museo di Storia delta Scienza houses two complete telescopes and a single objective lens (reconstructed from several fragments) that can be attributed to Galileo. These optics have been partially dismantled and made available for optical testing with state-of-the-art equipment. The lenses were investigated individually; the focal length and the radii of curvature were measured, and the optical layout of the instruments was worked out. The optical quality of the surfaces and the overall performance of the two complete telescopes have been evaluated interferometrically at a wavelength of 633 nm (with a He-Ne laser source). It was found in particular that the optics of Galileo came close to attaining diffraction-limited operation.

Multiphase homodyne interferometry: analysis of some error sources

Some sources of error with multiphase homodyne interferometry are reviewed. A major advantage over the classic two-channel approach is that the inaccuracies that originate from laser-power fluctuations and drifts are shown to be automatically compensated for by proper adjustment of the light beams.

Micro-temperature effects on absolute flatness test plates

High-sensitivity interferometric measurements on test plates are reported, showing peculiar variability maps of optical path difference. Micro-temperature deformations of the test plates are considered, accounting for the maps observed; orders of magnitude for the temperature disuniformities are evaluated. Thermal instabilities are pointed out as an effective limit to the feasibility and assessment of flatness etalons.

Reflection and refraction of narrow Gaussian beams with general astigmatism at tilted optical surfaces: a derivation oriented toward lens design

The formulas for the reflection and refraction of a narrow Gaussian beam with general astigmatism at a tilted optical surface are derived by ray-tracing techniques. The propagation direction of the reflected and refracted beams is computed by tracing the central ray of the incident beam, and the characteristic parameters of the respective wavefronts are worked out by applying the formulas developed for the generalized ray tracing. Moreover, the Gaussian form of the reflected and refracted amplitude distributions along the transverse coordinates is determined by requiring the matching of the incident, reflected, and refracted light spots on the optical surface. No limiting assumptions are made regarding the form of the optical interface or the orientation of the incident astigmatic wavefront. In the end, to illustrate a simple application of these formulas, the reflection of a Gaussian beam at a conicoid is considered, and a simple property of the conicoidal mirrors is reported.

Measuring the refractive index of thin liquid films with a spectrometer

We discuss the manufacture and use of a prism pair to measure the refractive index of thin liquid films with a spectrometer. The method requires only a drop of liquid and is accurate to ~2 x 10(-4).

One-step 360° rainbow holography with two spherical mirrors

A new optical configuration producing one-step 360° rainbow holograms is presented. The method makes use of two concave mirrors in confocal position, with an annular aperture between the two. An experimental demonstration is given.

Galileo Galilei: Research and development of the telescope

Publisher Summary This chapter describes Galileo Galileis research and development of the telescope. The personality and the work of Galileo Galilei have fascinated generations of scientists engaged in the advancement of knowledge. The scientific merits of Galileo, along with their philosophical implications, are celebrated and fully acknowledged today. In the case of the telescope, in particular, acquaintance with and mastery of optical engineering skills play a fundamental role in its development into a successful instrument. Only two telescopes and a single objective lens in the Science Museum of Florence remain. Galileos research and development of the telescope proceeded from a rumor of feasibility, to a working device presented to the Senate of Venice, and then to a fully engineered instrument used for astronomical observations. Further inspections have been made recently with state-of-the-art equipment. Finally, this chapter discusses the main results of such studies, outlining the engineering achievements that Galileo was able to obtain as related to the technological knowledge of his time.

Absolute measurement of planarity: pixel versus Zernike data analysis

Relating two different methods of data analysis for assessing the absolute planarity of reference flats is reported. Considered methods are based on Zernike representation and pixel handling, respectively. Operations to be implemented on interferometric systems to use the same data set for comparative processing are described.