Aligna
®
4D User Manual
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Table of Contents
1 Introduction ....................................................................................................... 7
2 Block Diagram Aligna
®
4D .............................................................................. 10
3 Short Description of the Front Panel Elements ............................................ 11
4 Principles of Laser Pointing Stabilization ..................................................... 12
4.1 Reasons of Pointing Instabilities ................................................................. 12
4.1.1 Thermal properties of the laser itself ................................................................. 12
4.1.2 Thermal movement by the laser cooling system ................................................ 12
4.1.3 Drifts of alignment and folding mirrors ............................................................... 12
4.1.4 Air turbulences and temperature gradients in the air ......................................... 12
4.1.5 Thermal effects of optical elements ................................................................... 13
4.1.6 Mechanically moved optical elements (delay lines, e.g.) ................................... 13
4.1.7 Movement of the experimental (optical) tables or vacuum chambers ................ 13
4.2 2D or 4D Stabilization? ............................................................................... 14
4.3 Positioning of Actuator and Detectors ........................................................ 17
4.3.1 Setup 1: Two Beam Samplers ........................................................................... 17
4.3.2 Setup 2: Second Mirror Acts as Beam Sampler ................................................. 17
4.3.3 Problems with Beam Sampler Plates ................................................................ 17
4.3.4 Setup 3: High Reflecting Mirror Acts as Beam Sampler ..................................... 18
4.3.5 Setup 4: Only One Beam Sampler Mirror .......................................................... 19
4.3.6 Setup 5: Compact 4D Sensor "PSD 4D" ............................................................ 19
4.3.7 Setup 6: "PSD 4D" with Beam Sampler Wedge Plate ........................................ 19
4.3.8 Distance between A1 and A2 ............................................................................ 20
4.3.9 Position of the Detector(s) ................................................................................. 20
5 Some Typical Configurations ......................................................................... 25
5.1 2D System (Angle Stabilization) ................................................................. 25
5.2 2D System (Long Path) .............................................................................. 25
5.3 4D System .................................................................................................. 26
5.4 4D System with Long Beam Path ............................................................... 26
5.5 Auto-Alignment and 2D stabilization ........................................................... 27
5.6 Auto-Alignment and 4D stabilization ........................................................... 28
5.7 Overlaying Two or More Laser Beams Independently ................................ 28
5.8 Overlaying Two Laser Beams, Commonly Stabilized Path ........................ 29
5.9 Overlaying Three Laser Beams with Commonly Stabilized Path................ 30
5.10 Comparison of some Setups ...................................................................... 31
6 Pulsed Lasers .................................................................................................. 32
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