THORLABS EXULUS-4K1 Instructions Manual page 10

Setting a specific gray level from 0 to 255 will set
the entire panel to a certain phase level.
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CGH Tab: Convert a user-defined image into a
holographic pattern. For more details, please see
the App Note tab.
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Pattern Tab for Diffraction Grating Generation:
Sets the SLM panel to diffract the reflected light with
user-selected wavelength, deviation angle, and
grating rotation angle. For more infromation about
the diffraction efficiency of different patterns, please
see the Diffraction Efficiency tab.
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Pattern Tab for Cubic Phase Generation: This
pattern generates a non-diffracted beam with self-
recovery characteristics, commonly called an airy
beam. The mode contains two parameters:
wavelength and alpha.
A P P N O T E
Overview
Two-dimensional spatial light modulators (SLMs) offer individually addressable pixels of phase shift.
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Thorlabs' Exulus 2D SLM is fabricated with liquid crystal on silicon (LCoS) technology, which is based
on display technology. This allows it to provide far more pixels than lower-order phase modulators such
as segmented or deformable mirrors. Also, the phase shift of one pixel has little crosstalk with other
pixels. Therefore, the Exulus 2D SLM is perfect for many beam manipulation applications including
optical trapping, beam steering and shaping, femtosecond pulse shaping, adaptive optics, imaging
applications, and holography.
The main component of the Exulus
between the top transparent and conductive ITO electrode, and the reflective electrode on the bottom. Each pixel on the SLM panel corresponds to individually
addressable electrodes on the bottom. Together with the ITO layer on top, an electric field is built up by applying a voltage between the two electrodes. The liquid
crystal modules line up according to the direction and strength of the electric field. Since liquid crystal is a birefringent material, the alignment of the liquid crystal
molecules in turn controls the retardance or phase shift of each pixel. A wavefront that is incident on the panel reflects with its phase or wavefront being shifted
according to the signal that is sent to the SLM panel. With a properly calculated pattern on the SLM panel, the reflected wavefront results in different optical
effects in the far field. These effects typically include diffraction, tilt, focus, and holographic image formation.
Pattern Tab for Fresnel Lens Generation: Sets
the SLM panel to focus the reflected light at a
user-selected wavelength and focal length.
Pattern Tab for Vortex Generation: This
pattern creates a helical output beam and contains
a characteristic donut beam profile. The mode
contains two parameters: wavelength and pattern
Sensor Setting: When a high-power SLM is
connected to the LK220 chiller, the temperature
sensor can be set to internal or external mode. The
internal sensor measures the output coolant
temperature, while the external sensor gives the
thermistor temperature reading from the LK220
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is the 2D SLM LCoS panel. Figure 1 shows a basic schematic of the LCoS panel. The liquid crystal layer is sandwiched
JPEG, or BMP format.
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order m.
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chiller.
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Figure 1: A schematic diagram of the SLM LCoS
panel.