THORLABS LCC1620 User manual

LCC1620(/M)
Liquid Crystal Shutter
User Guide

Liquid Crystal Shutter
Table of Contents
Chapter 1Warning Symbol Definitions..............................................................................................1
Chapter 2Safety....................................................................................................................................2
Chapter 3Product Overview................................................................................................................3
Chapter 4Setup.....................................................................................................................................4
4.1.Mounting and Alignment................................................................................................4
4.2.Power Supply...................................................................................................................4
4.3.Powering On the Shutter................................................................................................4
4.4.Beam Centering...............................................................................................................4
Chapter 5Operation..............................................................................................................................5
Chapter 6Specifications and Graphs................................................................................................6
Chapter 7Mechanical Drawing...........................................................................................................10
Chapter 8Maintenance........................................................................................................................11
8.1.Troubleshooting............................................................................................................11
Chapter 9CE Certification...................................................................................................................12
Chapter 10Regulatory...........................................................................................................................13
Chapter 11Thorlabs Worldwide Contacts..........................................................................................14

Liquid Crystal Shutter Chapter 1: Warning Symbol Definitions
Rev D, January 8, 2020 Page 1
Chapter 1 Warning Symbol Definitions
Below is a list of warning symbols you may encounter in this manual or on your device.
Symbol Description
Direct Current
Alternating Current
Both Direct and Alternating Current
Earth Ground Terminal
Protective Conductor Terminal
Frame or Chassis Terminal
Equipotentiality
On (Supply)
Off (Supply)
In Position of a Bi-Stable Push Control
Out Position of a Bi-Stable Push Control
Caution: Risk of Electric Shock
Caution: Hot Surface
Caution: Risk of Danger
Warning: Laser Radiation
Caution: Spinning Blades May Cause Harm

Liquid Crystal Shutter Chapter 2: Safety
Page 2 CTN002190-D02
Chapter 2 Safety
Do Not Open Housing!
The Liquid Crystal Shutter has no user-serviceable parts. Service should only be performed by
trained service personnel.
All statements regarding safety of operation and technical data in this instruction manual will only apply when the
unit is operated correctly.
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this
device may not cause harmful interference, and (2) this device must accept any interference received, including
interference that may cause undesired operation.
WARNING
Laser Radiation – Avoid Exposure to Beam

Liquid Crystal Shutter Chapter 3: Product Overview
Rev D, January 8, 2020 Page 3
Chapter 3 Product Overview
Thorlabs’ Liquid Crystal Shutters are precision, high speed shutters that are ideal as a laser switch. They consist
of a Liquid Crystal (LC) cell, an electronic controller unit, and a mechanical housing, shown below in Figure 1.
Figure 1 Liquid Crystal Shutter Block Diagram
The LC cell is sandwiched between two protective glass plates and two polarizers with crossed transmission
axes, shown below in Figure 2.
Figure 2 Liquid Crystal Cell Block Diagram
A line on the front of the housing (see Figure 3) marks the transmission axis of the shutter. Linearly polarized light
needs to be aligned with this mark for optimal shutter operation. When powered on, the LC cell is controlled by
the driving voltage, which can be controlled through the potentiometer on the top of the shutter (see Figure 4).
When fully powered, the LC cell will rotate the polarization axis of the input light by 90°, aligning it to the
transmission axis of the output polarizer and allowing it to propagate through the device without significant
attenuation. By adjusting the drive voltage, the amount of rotation can be controlled, and thus this device can also
function as a variable attenuator in addition to shutter functionality.

Liquid Crystal Shutter Chapter 4: Setup
Page 4 CTN002190-D02
Chapter 4 Setup
4.1. Mounting and Alignment
The shutter is optimized to work with an input beam that is linearly polarized with its polarization axis aligned to
the line on the front of the shutter. Both linearly polarized light and proper alignment of the polarization axis are
recommended for achieving the best performance from the shutter.
For post mounting, the shutter has two 8-32 (M4) threaded holes. They have a typical thread depth is 4.5 mm and
are offset by 90°, so that light with a vertical or horizontal polarization axis can be aligned with the shutter.
Additionally, the liquid crystal shutters are designed to be compatible with Thorlabs 30 mm cage systems. The
four 4-40 holes on the front of the shutter can also be used to mount the shutter in either a horizontal or vertical
orientation using the Thorlabs Cage System.
4.2. Power Supply
The shutter operates with a 12 VDC power and the power supply is included with the shutter.
4.3. Powering On the Shutter
When the shutter is connected to the power supply, it automatically powers on. There is no additional power
switch.
4.4. Beam Centering
For optimal performance, it is recommended that the beam is well centered in the input aperture.
Figure 3 Liquid Crystal Shutter

Liquid Crystal Shutter Chapter 5: Operation
Rev D, January 8, 2020 Page 5
Chapter 5 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 wave plate 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 user 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 LCC1620 (/M) 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” SMC 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.
Note: under “ATTENUATOR” mode, if the potentiometer is not turned clockwise fully, the “EXT INPUT” voltage
will not achieve full transmission. Instead it can vary from off to the attenuation level set by the potentiometer.
Figure 4 Top View of the Shutter

Liquid Crystal Shutter Chapter 6: Specifications and Graphs
Page 6 CTN002190-D02
Chapter 6 Specifications and Graphs
Item # LCC1620(/M)
Operating Wavelength Range 420 - 700 nm
Transmission (Avg.) >60%
Contrast Ratio (CR; Avg.)1 >8000:1
Laser Damage
Threshold
CW 1 W/cm2 (532 nm, Ø0.471 mm)
Pulsed 0.4 J/cm2 (532 nm, 10 ns, 10 Hz, Ø0.750 mm)
Clear Aperture Ø20 mm
Surface Quality 40-20 Scratch-Dig
Max Incidence Angle ±5°
Switching Speed
(Shutter Mode)2
Opening (Typ.) 5 ms
Closing (Typ.) 1 ms
Wavefront Distortion ≤λ/4 @ 633 nm
External Input SMC Connector, 0 - 5 V, 25 kΩ Input Impedance
Power Adapter 12 VDC / 1.25 A with Power Cord
AC Power Requirements 110 - 240 VAC, 47 - 63 Hz, 0.4 A
Mounting
Two 8-32 (M4) Threaded Holes for Post Mounting
30 mm Cage System Compatible
Ø1" Lens Tube Compatible
Operating Temperature 15 °C to 60 °C
Dimension 60 mm x 60 mm x 27 mm
Figure 5 Liquid Crystal Shutter CR and Transmittance
1 The average CR is specified over the operating wavelength range.
2 In shutter mode with a 0 - 5 V TTL input from the EXT port. Opening time is defined as the time taken for the TTL signal to fall to 10% and
the shutter transmission raise to 90% of the total transmitted power, while closing time is defined as the time taken for the TTL signal raise to
90% and shutter transmission fall to 10% of the total transmitted power.
400 450 500 550 600 650 700 750 800
0
10
20
30
40
50
60
70
80
90
100
Transmission
Contrast Ratio
LCC1620(/M) Transmission and Contrast Ratio
Transmission (%)
Wavelength (nm)
1
10
100
1000
10000
100000
Contrast Ratio

Liquid Crystal Shutter Chapter 6: Specifications and Graphs
Rev ',-DQXDU\ Page 7
Figure 6 Typical Shutter Transmission at Various Voltages
Figure 7 Typical Shutter Transmission by External Input (0 - 5 V) under “Attenuator Mode”
Note: all graphs showing CR data are shown in the base 10 logarithmic scale. All light is linearly polarized and
aligned in the direction of the transmission axis on the front surface.
350 400 450 500 550 600 650 700 750 800
0
10
20
30
40
50
60
70
80
90
100
0 V 0.5 V 1 V 1.5 V
2 V 2.5 V 3 V 5 V
LCC1620(/M) Attenuation
Transmission (%)
Wavelength (nm)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
0
10
20
30
40
50
60
70
80
90
100
500 nm
550 nm
600 nm
650 nm
700 nm
750 nm
LCC1620(/M) Transmission
Transmission (%)
Attenuation Voltage (V)

Liquid Crystal Shutter Chapter 6: Specifications and Graphs
Page 8 CTN002190-D02
Figure 8 Normalized Contrast Ratio vs. Frequency
Figure 9 Switching Time Stability