RESUMEN
We experimentally demonstrate that a femtosecond frequency comb laser can be applied as a tool for long-distance measurement in air. Our method is based on the measurement of cross correlation between individual pulses in a Michelson interferometer. From the position of the correlation functions, distances of up to 50 m have been measured. We have compared this measurement to a counting laser interferometer, showing an agreement with the measured distance within 2 microm (4x10(-8) at 50 m).
RESUMEN
We present details of a novel imaging algorithm based on the extended Nijboer-Zernike (ENZ) theory of diffraction. We derive integral expressions relating the electric field distribution in the entrance pupil of an optical system to the electric field in its focal region. The evaluation of these integrals is made possible by means of a highly accurate and efficient series expansion similar to those occurring in standard ENZ theory. Based on these results an ENZ imaging scheme is constructed and evaluated in detail with attention to the convergence properties and computational complexity of the new method.
RESUMEN
We propose and demonstrate a novel liquid deformable mirror, based on electrocapillary actuation, for high-order wavefront correction. The device consists of a two-dimensional array of vertically oriented microchannels filled with two immiscible liquids, an aqueous electrolyte, and a viscous dielectric liquid, where the dielectric liquid overfills the top end of the channel and forms a thin layer on top. To remedy the poor reflectivity of pure liquids, a free-floating reflective membrane or a dye-coated liquid can be used. The proposed device offers several advantages for adaptive optics applications. These advantages include a high number of actuators, high stroke dynamic range, low power dissipation, fast response time, an initially flat surface, and low cost. However, the device is mainly suitable for dynamic wavefront correction and is limited by its orientation.
RESUMEN
Absolute distance measurements can be performed with an interferometric method that uses only a single tunable laser. This method has one major drawback, because a small target movement of the order of one wavelength during a measurement will be interpreted as a movement of one synthetic wavelength. This effect is usually mitigated by adding a second (nonscanning) laser. We show that absolute distance measurements can be performed with only one laser if the movements encountered are smooth, on the time scale of one measurement. In this case the movement errors can be compensated with a simple algorithm that combines several subsequent measurements. First experimental results show good agreement with theory.
RESUMEN
A new interferometric technique for Michelson wide-field interferometry is presented that consists of a Michelson pupil-plane combination scheme in which a wide field of view can be achieved in one shot. This technique uses a stair-shaped mirror in the intermediate image plane of each telescope in the array, allowing for simultaneous correction of the differential delay for the on-axis and off-axis image positions. Experimental results in a laboratory setup show that it is possible to recover the fringes of on-axis and off-axis stars with an angular separation of 1 arc min simultaneously and with a similar contrast. This new technique represents a considerable extension of the field of view of an interferometer without the need for extra observation time.
RESUMEN
Bacteriorhodopsin (bR) is a reversible photochromic protein that can be used as a holographic medium. The dichroic absorption of the bR molecule is polarization dependent, thereby allowing for the recording of polarization holograms. The properties of polarization holograms can be used to multiplex two independent images in a single bR film. A new technique and associated polarization-multiplexing scheme are demonstrated that allow for simultaneous readout of two orthogonally polarized images while achieving a high normalized diffraction efficiency for each of the individual images.
