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Collimators

Use the template from RGOC position collimator 1 (C tex2html_wrap_inline102 ) on the collimator optical axis. Remove R tex2html_wrap_inline102 from its baseplate, remove the alignment post from the telescope end of the optical bench, and replace it with a perforated alignment target. The laser beam should now be striking the pole of the front lens of C tex2html_wrap_inline102 . Adjust the position of C tex2html_wrap_inline102 to get the back reflections and interference patterns coincident with the laser beam at the target. Replace R tex2html_wrap_inline102 and check the separation A tex2html_wrap_inline102 to the pole of C tex2html_wrap_inline102 - this should be 860.5mm. If necessary, adjust by using blocks to allow the complete collimator baseplate to slide along the collimator axis, and further clamping blocks and slip gauges to enable controlled adjustment. Minor adjustment of the longitudinal position of C tex2html_wrap_inline102 can be achieved using the micrometer on C tex2html_wrap_inline102 , but note this has a total range of 2.5mm, so it is best to put this in the centre of its range, and adjust using the method described above. Remove the alignment post closest to the laser, and replace it with one of the perforated targets. . Iterate on checking the separation between R tex2html_wrap_inline102 and C tex2html_wrap_inline102 and the back reflections until both are correct.

Use the same method to position collimator 2 (C tex2html_wrap_inline119 ). The separation between C tex2html_wrap_inline102 and C tex2html_wrap_inline119 should be 227.6mm. Remove C tex2html_wrap_inline102 to do the squaring on. (note: both at RGOC and when aligned at LPO it was not possible to balance the back reflections and interference patterns from C tex2html_wrap_inline119 perfectly -- see figure ?? for details. Again, it is necessary to iterate between separations and back reflections. Clamp the baseplate securely to the optical bench, and lock all adjusting screws on the kinematic mounts.