First approach to characterize tilts through multiple pistons in the classical Ronchi test.

In this work, it is shown how a tilt can be introduced into a segmented surface through several piston terms, by using the classical Ronchi test. We have developed tilt error simulations by adding multiple constant terms to each point on the sagitta surface of a segment using ray tracing. Thereby a comparison between simulated Ronchigrams for piston and tilt has been performed for two adjacent segments, so that it is possible to appreciate the tilt and piston effects on the shape of the patterns. As a result, we show the behavior of the central maximum of the fringes in the presence of tilt and/or piston. Additionally we present evidence of introducing tilting without changing the surface shape by adding multiple pistons, and a description of how to characterize both piston and tilt using the Ronchi test.

Improved Ronchi tester.

We used a LED in a Ronchi tester to obtain two main improvements: (i) We can choose one of two wavelength bands to illuminate and record the ronchigram, and (ii) we can change the irradiance of the illumination source according to the optical system under test and the detector array. This can be done by use of an adequate electronic circuit.

Optical alignment of segmented mirrors to the fluorescence detectors of the Pierre Auger observatory.

Segmented mirrors will be used in the telescopes of the Pierre Auger Fluorescence detector. To align the segments, we have developed four methods in which (a) the image of the stop border, (b) the image of a screen with concentric circles, and (c) the Ronchi pattern are used. In addition to these, we have developed a new method, (d), in which instead of the Ronchi ruling, we have used a circular grid. In this case we obtain a moiré pattern for each segment by means of which the experimental setup is simplified, and the sensitivity of the alignment is improved.