KEYWORDS: Polarization, Laser processing, Spatial light modulators, Laser systems engineering, Digital Light Processing, Internet of things, Holography, Phase shift keying, Optical signal processing, Manufacturing
The arbitrary dynamic control of both amplitude and polarization distributions is attracting strong interest in laser processing field to manage the quality and to collect valuable polarization characteristics of processing materials in smart manufacturing. We present a holographic method to generate arbitrary polarization state of multiple beams by synchronizing two phase-only liquid crystal spatial light modulators (SLMs) with imaging feedback system for hologram designing of each polarization state. This research work will help to accelerate the use of liquid crystal SLMs for high-throughput and optimized additive manufacturing.
We developed a liquid-crystal spatial light modulator having a 30 mm active area and a multilayered dielectric mirror for industrial infrared lasers to establish an innovative manufacturing and fabrication technique in the smart-manufacturing post-pandemic era. The reconstruction of computer-generated holograms was achieved to demonstrate the concept of this device in the IR region. The incident phase performance characteristics of this device under high-power laser irradiation were obtained using a 1030 nm ultrashort pulse laser. The work presented here will accelerate the use of liquid-crystal SLMs in high-precision laser processing of the process-resistant materials and high-throughput processing for additive manufacturing.
Conventional methods of compensating for self-distortion in liquid-crystal-on-silicon spatial light modulators (LCOS-SLM) are based on aberration correction, where the wavefront of the incident beam is modulated to compensate for aberrations caused by the imperfect optical flatness of the LCOS-SLM surface. Previously, we proposed an effective method to compensate for the distortion by displaying a compensation phase pattern obtained from interferometry However, the phase distribution of an LCOS-SLM varies with changes in ambient temperature and requires additional correction. The ambient temperature of LCOS-SLMs can vary under certain circumstances, i.e. equipped inside systems for field use or long-term operations. In this presentation, we discussed a novel phase compensation method under temperature-varying conditions based on an orthonormal Legendre series expansion of the phase distribution from viewpoint of multiple beam holographic generation. We found several Legendre coefficients that follow quadratic functions of ambient temperature. This prompted us to propose an algorithm for correcting the temperature dependency by displaying a phase pattern using two simple steps: an initializing step and a temperature correction step. We investigated the temperature dependency by controlling the ambient temperature with an incubator and successfully corrected for self-distortion in a temperature range of approximately 68°F to 122°F, giving an optical flatness of <λ /10. Our approach has the potential to be adopted in tight-focusing applications which require wavefront modulation with very high accuracy. Additionally, the concept of this method is extensible to the thermal behavior of other optical devices, such as lenses and mirrors, which have the possibility of causing unexpected aberrations.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.