Renishaw HS20 Installation Manual page 44

40
HS20 laser beam alignment
Achieving an optimum alignment of the laser and optical components forms a very important part of
the installation of the system, and therefore care should be taken in aligning the optical components.
There are many different techniques for aligning a laser system and which technique is used is often a
matter of personal preference. This manual describes a simple method using the HS20 alignment plate.
It is recommended that the HS20 laser head is aligned using the alignment plate for coarse alignment
of the beam along the axis. Then using an LS06 Beam Steerer (A-8003-2898) to fine tune the laser
alignment.
WARNING: DO NOT STARE INTO BEAM - CLASS 2 RADIATION
WARNING: If the laser beam is misaligned during beam alignment, the tristated quad will be asserted
due to low signal strength. Also if the laser beam is misaligned such that the return beam enters the
laser output port, it is possible that the laser will be destabilised. This is normal behaviour, and again
the tristated quad may be asserted. Under either circumstance the laser position feedback signals
may be invalid. For this reason initial beam alignment should be performed with the machine under
manual or open loop control.
Firstly the HS20 and alignment plate are fitted to the machine as described in Section 2 'Mechanical
Installation'. Then the alignment plate adjustments and HS20 adjustment feet are set to the mid-point of
travel. It is assumed that the measurement retroreflector cannot be adjusted, so that any adjustments are
performed with the interferometer assembly and/or HS20 laser head. It is often easier to have two people
work together when performing alignment; one to make adjustments at the laser end, and a second to
call out directions from the far axis position. It can also save time to perform the alignment for both sides
of a split feedback axis at the same time. This reduces the amount of machine movements required.
The laser beam-path ducting should not be fitted at this time, as this will make the alignment process
much easier.
LS06 operation
Horizontal and vertical adjustment is achieved by using a 'triple-wedge-prism' system. This involves
two adjustable wedges and one fixed. The adjustable wedges are rotated by means of external levers,
which direct the laser beam onto the desired target.
The operation of the laser steerer is explained in figure 39. Lever 'A' controls the vertical plane of the
laser beam as it passes througth the unit and lever 'B' controls the horizontal plane. Once the desired
alignment has been achieved the external levers need to be locked into position using the rotational
locking screws provided.
Figure 39 - HS20 status lines (machine I/O inputs)