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LST400 Laser Shutter Specifications
Aperture Diameter 8.0 mm
Typical Beam Diameter used for Specs 6.0 mm
Maximum Shutter Repetition Rate 5 Hz
CW and Quasi-CW Optical Power Handling 50 W Max
Typical Damage Threshold, Aligned Polarization 300 mJ/cm2
Delay to Begin Opening after Command Open 10 ms
Opening Time Switching Speed 15 ms
Delay to Begin Closing after Command Close 5 ms
Closing Time Switching Speed 15 ms using CX4000B
LST400 Laser Shutter Specifications
Minimum FWHM Exposure Capability 30 ms using CX4000B
Thermal Power Dissipation Holding Open 4 W
Thermal Power Dissipation, Repetitive Cycling 8 W @ 3 Hz
Nominal Magnetic Winding Impedance 15 Ohms
Cable/Wire Type and Length 18 inches, 6 leads 22 g
Mounting Surface for Thermal Sinking Base Plate
Position Sensors Logic TTL, Require 5 VDC @ 20 mA
Weight 4 oz.
Size (see mechanical drawing) 3.80 x 2.06 x 0.64 Inches
Note: 3-D solid model available upon request (Solidworks or .stp file)
Specifications updated on March 30, 2021


The LST400 laser shutter model is designed for use as a laser safety interlock and for some laser processing applications. The LST400 provides TTL output position sensors for the open and closed states as standard equipment. The thin body style and 8 mm aperture accommodate many popular laser sources. The –IR suffix replaces the over-coated aluminum mirror with gold, for use in the IR, including CO2. This option must be used for CO2 lasers.

Compatible system controllers are CX4000B or user-built circuits designed around 24 VDC.

Options are available using a suffix code system. Many options cannot be installed after manufacture, so choose carefully. Choose the –IR suffix for CO2 and IR use, starting at about 700 nm. The standard over-coated aluminum mirror is good from deep UV to about 4 microns. Special mirrors are not currently available, except for OEM applications. Cable options are available, call for details.

Special Considerations for this model include damage threshold assessment. The shutter is not designed for high energy, low repetition rate Q-switched lasers. See LSTXYW8 for these applications. Thermal mounting must be given strong attention if optical power dissipation is near the upper limit of the rating. For high activity processing, consider the LST200SLP.

Restricted use for this model is only limited to damage threshold and wavelength considerations. It can be used in any orientation with regards to gravity.

See the Mechanical Drawing tab for dimensions. Also see the Application Notes in the Technical Information menu for important operational issues including: thermal mounting, user-built circuits, polarization, lifetime, jitter, vacuum operation, and contamination. See the Product Matrix page to compare laser shutter models.


LST400 Laser Shutter Custom Options

Aperture Size Range 8mm to 12mm (round or obround)
Optics Aluminum, Dielectric, Gold
Wire Length Any length
Wire/Cable Type Wire Gauge Teflon, Vinyl
Connector Any 6 pin connector
Size 3.80 x 2.06 x .64 in., note: minimal size change can be designed
Identification Engraving, Labels

Mechanical Drawing

LST400 Laser Shutter Mechanical Drawing
Note: 3-D solid model available upon request (Solidworks or .stp file)

Electrical Drive

LST400 Laser Shutter Electrical Drive

Classification Safety/Process
Number of Wire Leads, Std. Six, 22 g
Cable or Wires – Length 18 inches
Cable/Wire Termination MTA-100, AMP, P/N 643813-60
Recommended Controller and Voltage Present Capacitor Discharge 24 V, 24 V PWM,- or our controllers
Shutter Winding Resistance 15 Ohms Nominal
Gravity Considerations Symmetric Open/Close speed with base down More power needed for upside-down mounting
Typical Minimum Hold Open Voltage, Room Temperature Room Temperature, 5 V
Typical Hold Open Power Dissipation as Heat 4 W
User Power Supply Notes 24 V, 1 A Rating, Surge Capacitor on output
User Drive Circuit/Cap Discharge 24 V, C=4 700 mmF, R=50 ohm, Use Flyback diode 1N4001
Nominal Winding Inductance 10 mH
User Drive Circuit/PWM Type 24 V for 50 ms, then drop to 7 V hold, Use 1N4001 Flyback
Color Codes and Function of Wires PIN 1 Red, + to winding
PIN 2 Black, – to winding
PIN 3 Violet, Supply Regulated +5.0 VDC — 30 mA
PIN 4 Yellow, NO Output from Sensor, TTL (reads high when shutter open)
PIN 5 Orange, NC Output from Sensor, TTL (reads high when shutter closed)
PIN 6 Blue, 5V Return and Sensor Ground
Read sensor outputs with reference to the blue ground wire. These outputs are totem-pole buffered TTL, seeking a load of ~10 K ohms. Typical output is 4 V. Do not try to draw more than about 5 mA from the Yellow or Orange Outputs, or the voltage will load down.