HP 5501A Operating And Service Manual page 69

F~gure 2-39. Laser Head Installation
In Figure 2-40 one of the two parallel light beams reflected from above enters the fixed Y-axis
linear interferometer. There the measurement beam is deflected 90° to the moving Y-axis
retroreflector (shown in Figure 2-47) attached to the Y-axis machine slide. The other laser
beam reflected from above enters a beam bender next to the interferometer where it is de-
flected to the X-axis measurement optics.
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Figure 2-40. Y-.
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