The European Southern Observatory's (eso) Very Large Telescope consists (vlt) of four 8-meter telescopes which can work independently or in combined mode. In the latter mode the vlt provides the total light collecting power of a 16 meter single telescope, making it the largest optical telescope in the world. The four 8-m telescopes supplemented with 3 auxilliary 1 m telescopes may also be used in interferometric mode providing high angular resolution imaging: vlt Interferometer, vlti. The useful wavelength range extends from the near uv up to 25 microns in the infrared.
Optical Delay Line cart for ESO's Very Large Telescope
Dutch Space is responsible for the design, development en delivery of the so called vlti delay lines. The delay line operates in the heart of the interferometer of the vlt and its performance is crucial for the quality and performance of the complete telescope.
European Southern Observatory at Paranal
The delay lines make certain that a length of the path followed by the light of a star remains the same, independ of the telescope through which it has been caugth. Only in this way the images from the telescopes can be combined. Because the telescopes are standing tens of meters apart and because the earth rotates along its axis, the length of the light path changes continuously. The principle of the solution is simple: use mirrors on a cart to adjust the length of the light path continuously. The real challenge is posed by the level of precision required: the carts of the vlt succeed in positioning the mirrors with an accuracy of better than 10 nanometers on a track of 60 meters.
