Liquid Crystal Shutters Chapter 4: Operation
Page 6 CTN018794-D02
Chapter 4 Operation
•Ensure that the input beam is linearly polarized and that the
polarization axis is aligned with the marking on the front of
the shutter. A polarizer or waveplate can be used to ensure
the polarization axis is aligned to the shutter. For best
performance, ensure the beam is at normal incidence to the
shutter and is aligned straight through the center of the LC
cell.
•Connect the power supply to the shutter.
•The shutter may operate either as an on/off shutter or a
variable attenuator. A slide switch on the top of the shutter
(see Figure 4) allows the used to select one of these two
modes of operation. When the “SHUTTER” mode is selected,
the potentiometer is used to simply to block or transmit the
beam. In this operational mode, when the potentiometer is
turned fully counterclockwise, the shutter is in the off
position, which is indicated by a red LED. Turning the
potentiometer will eventually switch the shutter from off to
on. When in the on position, light is transmitted through the
shutter, which is indicated by a green LED. When the
“ATTENUATOR” mode is selected, the potentiometer is used
as an adjustable attenuator. Turning the potentiometer
clockwise will increase the power transmitted through the
shutter. The green LED light is always lit in “ATTENUATOR”
mode.
•The shutter is also designed to be controlled by an external
signal. The external signal is a 0 – 5 V DC signal input into the
“EXT. INPUT” SMA connector. To use an external input in
“SHUTTER” mode, the potentiometer must be in the turned
fully clockwise. Whereas, in “ATTENTUATOR” mode, the “EXT
INPUT” adds an offset to the level set by the potentiometer.
Thus, if the potentiometer is fully counterclockwise, the “EXT
INPUT” has no effect. The “EXT INPUT” starts to take effect
when the potentiometer is turned clockwise and takes the
full effect when the potentiometer is fully clockwise.
