EXULUS Spatial Light Modulators - Principles and Applications

An introduction to liquid-crystal-based spatial light modulators (SLMs), including basic SLM principles, structures, and applications, is presented. Learn how to perform some basic tasks and how to optimize SLM devices for optimal performance. For more information on Thorlabs' EXULUS SLM product family, visit www.thorlabs.c....
Presented by Dr. Yat Hei Lo, Liquid Crystal Product Line Manager, Thorlabs China
For more, visit www.thorlabs.c....

[@juyoungkim3458]

Thanks for the video. When generating vortex beam, are you using 1st order diffraction? Or just used 0th order diffraction beam?

[@thorlabs]

Thank you for your question. We used the 0th order diffraction beam.

[@amityadav-bw8dj]

Thank for the video. can you explain about displaying the object without hologram.

[@thorlabs]

In principle, one can image the panel directly onto another screen or white board. Then what’s on it can be directly projected onto the next screen, though this is not the usual purpose of an SLM.

[@WaffleStaffel]

This is very neat. I'm interested in holograms. From my limited inquiry, it seems digital hologram printing made a limited debut, then quickly died due to its finding limited success in marketing/point of sale applications. I'm curious if there currently exist any "turnkey" hologram printing devices, or even services.

[@thorlabs]

Glad you liked it! The EXULUS, and in particular the HP series, can be useful for laser writing based on holograms. If you’re looking for a digital hologram printer that creates a 3D-like image on a substrate, or something that cures epoxy, ink, or similar materials, the EXULUS is probably not the right fit. In general, the EXULUS spatial light modulator dynamically transforms an input beam into a patterned profile as a 2D projection on an image plane, which enables applications including optical tweezers, multiphoton excitation, and laser writing. If you have a specific application in mind, feel free to follow up with us at [e-mail].

[@Ayurvedaism]

Thank you for the video! Can you share the lens specifications that you use to project the hologram?

[@thorlabs]

The lenses added to the beam path at 20:55 are a pair of Ø1” plano-convex lenses with focal lengths of 50 mm and 75 mm. These were chosen based on the desired size of the final projection and the focal length setting in the EXULUS software. In general, the shorter the EXULUS focal length setting, the smaller the image, and the closer the image forms to the spatial light modulator. Increasing the magnification with the imaging lenses would then allow a similar projected image size. You can read more about this kind of application on our website: www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=10378&tabname=App%20Note#tabTitles

[@yogalghimirey63]

I'm trying to use a similar setup for my thesis , would be great if you provide me which polarizer , halfwave plate and reflecting mirror is used , for generating array profile , I'm stuck with the setup . it would be very helpful if I can contact via email .

[@thorlabs]

Hi Yogal, thanks for your interest! Although any components designed for use with the laser wavelength should work, the setup shown at 13:43 incorporated our LPVISE100-A Linear Polarizer, WPH10M-633 Zero-Order Half-Wave Plate, and PF10-03-G01 Protected Aluminum Mirror. Within the setup, the polarizer is used to clean up the polarization of the laser light; in situations where the laser’s output polarization is already clean, the polarizer is not necessary. You’ll want to rotate the half-wave plate so that its polarization axis aligns with the SLM's axis. It is easy to tell when this state is achieved as the desired pattern becomes clear once the polarization angle is optimized. If you need any further assistance, we would be happy to help!

[@yogalghimirey63]

@@thorlabs I have been tasked to bend the light in parabolic way , I have setup my experiment as it is shown in your setup . I could not get the perfect image in CCD and my aim is to bend the light in parabolic pattern .

[@thorlabs]

@@yogalghimirey63 Thank you for your response! Can you please describe your experiment in more detail? Why is there a parabolic requirement? And what is the parabolically bent light being sent to downstream?

[@md.faiyazjamil7898]

What imaging lenses are used here at 20:58 and how do you compensate for the reduced contrast?

[@thorlabs]

The lenses that we use are the same as those in the App Note tab as in the product page ( www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=10378 ): an f = 50 m (LA1131-A-ML) followed by an f = 75 mm (LA1608-A-ML). Note that the choice of the lenses can be very flexible. It depends on the desired size of the final projection, and how short the effective focal length of the CGH is set in the software. The shorter it is, the smaller of the first image is formed and is closer to the SLM unit. Then, one needs more magnification with the imaging lenses in order to achieve similar projected image size. Regarding contrast, unfortunately the central zero-order spot exists due to the hardware itself (gaps between pixels are not processed by the SLM). While expanding the zero order and re-imaging the CGH projection can help distribute the zero-order spot to a larger area, hence a less prominent central spot, the contrast of CGH image itself is inevitably reduced. We have not systematically tested, but one could try setting a smaller focal length in the software CGH settings, and re-image using higher power lens system. This basically means spreading the zero-order spot even further out, which may help maintain a better contrast.

[@md.faiyazjamil7898]

@@thorlabs We are using this with the modular optical tweezer (OTKB). Can you tell me which lenses will be suitable to use with the system?

[@thorlabs]

@@md.faiyazjamil7898 You can first try to project the CGH image as demonstrated in the video and then revise the lens combinations for an image size that is compatible with your tweezer system. You can also add another lens relay to further reduce the image size. For more specific information about lenses that could be compatible with your specific setup, please contact Tech Support at [e-mail].