the autocorrelation of the binary star in the full pupil mode (cf., §3.1) and measure the rotation angle to align the slit on the direction of the two components.

– rotate the telescope flange supporting PISCO and center the object on the slit.

– switch to the spectroscopic mode and record the data.

Restoration of high angular resolution information in the direction of the entrance slit is then done by applying one-dimensional speckle imaging techniques to each monochromatic image of the slit (see §5.2).

The first spectroscopic observations were made in 1995. Unfortunately the poor seeing conditions and the low dynamic range of the detector did not allow us to restore high resolution images. We simply obtained long integration spectra (Fig 5774) and calibrated the whole instrument with known stars.

=8.8cm

Figure 7: First spectrum obtained with PISCO (HD 5774).

[*3.5. Wavefront analyzer*]{}

The atmospheric wavefront can be sensed with the Shack-Hartman method (Roggeman [*et al.*]{}, 1997), by putting a microlens array into the pupil plane (P1) and a specific imaging lens in the GR wheel, (cf. Fig. ). Each microlens has a diameter of 0.7 mm which corresponds to 20 cm on the pupil at the TBL and 10 