Modulation, Exposure and Pulse Gating Shutter Tutorials
This family of laser shutters offers the fastest switching speeds and high sustained repetition rates. Modulation can be as high as 500 Hz on custom models, with exposures as short as 800 microseconds at FWHM. Single pulse extraction can be made from 2 KHz or lower pulse trains.
The fastest speeds are for the smaller aperture diameters, starting at 2.3 mm. Usually, the laser shutter package size and optical power rating escalates with increasing aperture size. Switching speeds slow with larger apertures, in a non-linear fashion.
The majority of packages are designed for common applications with commercially available lasers and high irradiance lamp sources.
Laser shutter models are arranged in formats that indicate how the beam is intercepted by the moving flexure optic; the LS Models use near grazing incidence reflection principles and the LST Models use 45 degree incidence.
In general, the LS laser shutter models move less mass, providing faster switching speeds. They also provide higher damage threshold since the beam is spread over a large elliptical area of the flexure optic.
Angles of incidence range from about 82 to 75 degrees on LS Models, increasing the area of incidence and reducing the fluence by factors of 4-6. If the laser source is polarized, the damage threshold and optical power handling is further increased by aligned the polarization vector to the label on the product input aperture. This takes advantage of higher reflectivity of S polarization for near grazing incidence.
The absorber can handle a great deal of power, and usually the optical power rating and LIDT is limited by the flexure optic.
The standard coating is a broadband aluminum coating. Gold is available for exclusive use in the IR by adding suffix –IR to the model number. At CO2 wavelengths, absorbers change as well, and the –C2 suffix is attached to the model number.
Models in this high speed family do not have position sensor options. Extended cables can be ordered, with some limits due to voltage drop with distance.
These laser shutter models require more electrical power to provide fast switching speeds, and therefore dissipate more heat. Proper thermal mounting is mandatory to achieve stated performance and to avoid damage. See Thermal Mounting in the application notes section.
These models require the CX4000B model laser shutter controller. Larger aperture models can benefit greatly from the dampened movement control provided by the controller.