Laser scanning with spatial light modulators

Spatial Light Modulator (SLM)
What is SLM?
• An device that imposes some form of
spatially-varying modulation on a beam
of light.
• It can modulates the intensity or phase
of the beam or both the intensity and
the phase simultaneously.
Hamamatsu X10468 Series
• Liquid crystal on silicon (LCOS) chip based Phase-Only Modulator
・ Pure, linear and precise phase control
・ High light utilization efficiency
・ High diffraction efficiency
・ Compact
・ Ease of use(DVI compatible)
・ Reflective type
LCOS chip
・ Laser material processing
・ Optical manipulation
・ Wavefront correction
・ Pulse shaping
・ Optical testing
Hamamatsu, X10468 series manual, 2009
How it works
Ai  A0 ei0( x, y)
Ao  TSLM  Ai
 y
 
LG01 Hologram  ( x, y)  tan 1  
Transmittance at SLM
TSLM ( x, y)  A( x, y)ei ( x, y )
where, A( x, y)  1
By modulating the phase of incident light, the
intensity of output light can be changed.
Phase Modulation Characteristic
The X10468 series can achieve phase modulation of more than 2π
radians over the 400-1100 nm readout wavelength range.
The phase modulation curves for 95 % pixels lies within +/- 2σ .
Check that the PC and the LCOS-SLM controller are turn off.
Turn on the PC.
Change the display properties. Connect the second display. (LCOS-SLM)
Change the properties of the second display as shown below.
Display size: 800 x 600 (SVGA)
Refresh rate: 60 Hz
Colors: True color (32 Bit)
Turn on the LCOS-SLM controller. All LEDs will illuminate temporarily.
Check that the error lamp in the LCOS-SLM controllers is not illuminated or
flashing continuously. If the error lamp is illuminated or flashing continuously, the
PC settings may be wrong, or the cables may not be properly connected.
When the power is turned on, the LCOS-SLM warms up for about 10 seconds,
during the POWER LED flashes. You can start using the LCOS-SLM after that. The
OUTPUT LED flashes for five minutes to indicate that the device is warming up;
please refrain from using it during this time.
This procedure should be kept if the error lamp in the LCOS-SLM
controllers is lit or flashing.
Display setting
• Set the resolution of 2nd
monitor to 800x600.
• The 2nd monitor will be
recognized as LCOS-SLM.
Display the hologram on
SLM using C++
Retrieving monitor info.
• EnumDisplayDevices: retrieves
information about one of the graphics
modes for a display device
• EnumDisplaySettings: obtain
information about the display
devices(monitors) in the current session.
• Include “windows.h” to use these
Reference: Microsoft MSDN
Useful OpenCV GUI functions
OpenCV is a computer vision library originally developed by Intel. It
is free for commercial and research use under the open source BSD l
icense. The library is cross-platform, and runs on Windows, Mac OS
X, Linux, PSP, VCRT (Real-Time OS on Smart camera) and other embe
dded devices. It focuses mainly on real-time image processing.
To use these functions, install OpenCV.
Copy “cxcore100.dll” and “highgui100.dll”
located at C:\Program Files\OpenCV\bin in
And include “highgui.h” and link “cxcore.lib
and “highgui.lib” in the program
Reference: Intel® Open Source Computer
Vision Library
cvNamedWindow, cvDestroyWindow
cvMoveWindow, cvShowImage
cvWaitKey, cvReleaseImage
Sample code
Displayed on the SLM

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