Polarimetric Instrumentation

The polarization measurement of light and the materials response is performed by Stokes and Mueller polarimeters (using the Mueller formalism). One part of our study is focused on the design and optimization of polarimeters based on birefringent materials, including liquid crystal and biaxial-crystals (the latter group based on the conical refraction phenomenon).

Liquid crystal polarimeters

We have studied the use of liquid crystal cells of different types to implement Stokes and Mueller polarimeters for both punctual and image polarimeters.

Parallel aligned nematic cells

  • We have studied a complete Stokes polarimeter based on two parallel aligned nematic liquid crystal (PA-LC) cells is studied. This architecture is completely versatile because it allows implementing any polarization analyzer (PA) by addressing the proper pair of voltages to the LC cells.
  • It is a time-division polarimeter architecture. We have measured the transitory time of our PA-LC cells and it is around 300 milliseconds.
  • The equally weighted variance (EWV) of optimized configurations decreases as the number of polarizing analyzers (PAs) increases
  • From the tolerance analysis, we assert that the polarimeter has a larger tolerance on the retardances of the liquid crystals than on the orientation of the optical elements. In particular, for an accuracy in the Stokes vector measurement of 0.02 (1% of the total range), the tolerances of the retardances are 0.89º and 1.15º, and of the orientations are 0.50º and 0.54º, respectively for the first and second PA-LC cells oriented at 45º and 0º.

Twisted nematic cells

  • We have proposed a complete Stokes polarimeter based on a single TN-LC cell. We have proposed several configurations to study the influence of some physical parameters on the polarimeter performance. The idea is to achieve alternative characteristic curves which enlarge the volume enclosed, improving the optimization of the system.
  • They are time-division polarimeter architectures. We have measured the transitory time of our TN-LC cells and it is around 300 milliseconds. 
  • We have optimized the 6 different polarimeters by minimizing the EWV. To this aim, two different parameters are revised: first, the orientation of the linear polarizer (and the orientation of the QWP if used) and second, the 4 voltages to be addressed to the LC.
  • We have analyzed the influence of the physical parameters of the TN-LC cell (maximum birefringence and twist angle) on the optimization of the polarimeter via numerical simulations. The most suitable TN-LC cell for a polarimeter implementation has a twist angle from 40° to 140°, and a birefringence larger than 200º, although there is no need to be larger than 250° since no improvement in the optimization is observed. Thus, the use of a super-twisted nematic LC cell, to be used for polarimeter implementations, is not required.
  • From the tolerance analysis, we assert that TN-LC based polarimeters have a larger tolerance on the retardances of the liquid crystal and of the QWP than on the orientation of the optical elements. Particularly, for the polarimeter using normal incidence to the TN-LC cell and a QWP (set-up D), for an accuracy in the Stokes vector measurement of 0.02 (1% of the total range), the tolerance of the voltage addressed to the LC is of 0.0044V, the WP retardance is 1.69º, the orientation of the linear polarizer is 0.66º and of the QWP is 0.55º.

Ferroelectric cells

  • Complete Stokes and Mueller polarimeters based on two and four ferroelectric liquid crystal (FLC) cells have been proposed, respectively. Both polarimeters are time-division polarimeters architectures. The transitory time of our FLC cells has been measured, and it is around 0.3 milliseconds. Thus, FLC based polarimeters are appealing instruments for polarimetric applications where fast measurements are required.
  • We have applied a minimization of the condition number of the polarimetric measurement matrix. In such way, the optimal values for the optical model, being in this case the orientation of the FLC cells present in the set-up, are determined. We have obtained a CN of 2.22 for Stokes polarimeter and of 5.00 for the Mueller polarimeter.
  • From the tolerance analysis, we assert that the FLC based polarimeter has a larger tolerance on the retardances than on the orientations and rotations of the FLC cells. In particular, for ensuring an error in the Stokes measurement lower than 0.02, the tolerance of the optical parameters of the FLC panels are restricted to the following values: 1º for the retardance, 0.3º for the orientation of the fast axis and 0.4º-0.6º for the rotation of the fast axis. Moreover, the tolerances for the Mueller polarimeter to get an accuracy of 0.02 are also obtained: 1º-1.3º for the retardance, 0.3º for the orientation of the fast axis and 0.4º-0.6º for the rotation of the fast axis. 

  1. A. PeinadoLizana, A., and Campos, J.“Design of polarimeters based on liquid crystals and biaxial crystals for polarization metrology”, Opt. Pura Apl, vol. 49, pp. 167-177, 2016.
  2. A. PeinadoLizana, A.Iemmi, C., and Campos, J.“Polarization imaging with enhanced spatial resolution”, Optics Communications, vol. 338, pp. 95 - 100, 2015.
  3. A. PeinadoLizana, A., and Campos, J.“Use of ferroelectric liquid crystal panels to control state and degree of polarization in light beams”, Optics Letters, vol. 39, pp. 659-662, 2014.
  4. A. PeinadoLizana, A., and Campos, J.“Design of a polarimeter with two ferroelectric liquid crystal panels”, Proceedings SPIE, vol. 8873, p. 88730S-1-, 2013.
  5. A. LizanaPeinado, A.Ramírez, C.Martínez, J. L.Hussain, A.Sohail, M.Iemmi, C.Márquez, A.Moreno, I.Yzuel, M. J., and Campos, J.“Different Applications of Liquid Crystal Panels”, Proceedings SPIE, vol. 8785, pp. 87850Y-1-12, 2013.
  6. A. PeinadoLizana, A., and Campos, J.“Optimization and tolerance analysis of a polarimeter with ferroelectric liquid crystals”, Applied Optics, vol. 52, pp. 5748-5757, 2013.
  7. A. PeinadoLizana, A.Vidal, J.Iemmi, C., and Campos, J.“Optimized Stokes polarimeters based on a single twisted nematic liquid-crystal device for the minimization of noise propagation”, Appl. Opt., vol. 50, pp. 5437–5445, 2011.
  8. A. PeinadoLizana, A.Vidal, J.Iemmi, C., and Campos, J.“Study of polarimeters based on liquid crystal panels”, Proc. SPIE, vol. 8001, p. 80011Y-80011Y-11, 2011.
  9. A. PeinadoLizana, A.Vidal, J.Iemmi, C., and Campos, J.“Study of stokes polarimeters based on a single twisted nematic liquid crystal panel”, Proc. SPIE, vol. 8160, p. 81600R-81600R-9, 2011.
  10. A. PeinadoLizana, A.Vidal, J.Iemmi, C., and Campos, J.“Complete Stokes polarimeters based on liquid crystal displays”, Proc. SPIE, vol. 7797, p. 77970V-77970V-12, 2010.
  11. A. PeinadoLizana, A.Vidal, J.Iemmi, C., and Campos, J.“Optimization and performance criteria of a Stokes polarimeter based on two variable retarders”, Opt. Express, vol. 18, pp. 9815–9830, 2010.
  12. A. PeinadoLizana, A.Vidal, J.Iemmi, C.Márquez, A.Moreno, I., and Campos, J.“Variable waveplate-based polarimeter for polarimetric metrology”, Proc. SPIE, vol. 7390, pp. 739008-739008-12, 2009.

Conical refraction polarimeters

We have studied the conical refraction fenomenon to build polarimeters and to generate vectorial beams with special characteristics.

Conical refraction as a tool for polarization metrology

  • We have shown that the characteristic intensity pattern associated to the conical refraction (CR) phenomenon occurring in biaxial crystals can be used to build Stokes vector metrology.
  • We have proposed a new design of a division of amplitude complete and punctual Stokes polarimeter based on a beam splitter and two biaxial crystals. The set-up requires of two cameras to acquire the intensity distribution along the CR light rings. Although other punctual polarimeters only require one radiometer, this drawback is compensated by the strengths of the biaxial crystal based polarimeter, namely: no electrical addressing is needed, snapshot polarimeter, static measurements (no moving elements) avoiding misalignments errors and large data redundancy (leading to small variances for the different Stokes channels).
  • It is a snapshot Stokes polarimeter, only limited by the exposure time of the camera, and data redundancy can be increased without an increase of the measuring time.
  • From the tolerance analysis, we assert that CR based polarimeters have a larger tolerance on the retardance of the QWP than on the QWP orientation and on the orientation of both rings. In particular, to achieve an accuracy in the Stokes vector measurement of 0.02 (1% of the total range), the tolerance of the QWP orientation is 0.57º, of the QWP retardance is 1.15º and of the rings orientation of 0.57º.

  1. I. EstévezLizana, A.Turpin, A.Sopo, V.Ramírez, C.Peinado, A., and Campos, J.“Snapshot Stokes polarimeters based on a single biaxial crystal”, Proc. SPIE, vol. 10110, 2017.
  2. I. EstévezSopo, V.Lizana, A.Turpin, A., and Campos, J.“Complete snapshot Stokes polarimeter based on a single biaxial crystal”, Opt. Lett., vol. 41, pp. 4566–4569, 2016.
  3. A. LizanaEstévez, I.Turpin, A.Ramírez, C.Peinado, A., and Campos, J.“Implementation and performance of an in-line incomplete Stokes polarimeter based on a single biaxial crystal”, Appl. Opt., vol. 54, pp. 8758–8765, 2015.
  4. A. PeinadoTurpin, A.Iemmi, C.Márquez, A.Kalkandjiev, T. K.Mompart, J., and Campos, J.“Interferometric characterization of the structured light beam produced by the conical refraction fenomenon”, Optics Express, vol. 23, pp. 18080-18091, 2015.
  5. A. PeinadoLizana, A.Turpin, A.Iemmi, C.Kalkandjiev, T. K.Mompart, J., and Campos, J.“Optimization, tolerance analysis and implementation of a Stokes polarimeter based on the conical refraction phenomenon”, Optics Express, vol. 23, pp. 5636-5652, 2015.
  6. A. TurpinLoiko, Y. V.Peinado, A.Lizana, A.Kalkandjiev, T. K.Mompart, J., and Campos, J.“Polarization tailored novel vector beams based on conical refraction”, Optics Express, vol. 23, pp. 5704-5715, 2015.
  7. A. PeinadoLizana, A.Turpin, A.Estévez, I.Iemmi, C.Kalkandjiev, T. K.Mompart, J., and Campos, J.“Snapshot polarimeter based on the conical refraction phenomenon”, Proceedings SPIE, vol. 9526, pp. 952616:1-8, 2015.
  8. A. TurpinVargas, A.Lizana, A.Torres-Ruíz, F. A.Estévez, I.Moreno, I.Campos, J., and Mompart, J.“Transformation of vector beams with radial and azimuthal polarizations in biaxial crystals”, Journal of the Optical Society of America A, vol. 32, pp. 1012-1016, 2015.
  9. A. PeinadoTurpin, A.Lizana, A.Fernández, E.Mompart, J., and Campos, J.“Conical refraction as a tool for polarization metrology”, Optics Letters, vol. 38, pp. 4100-4103, 2013.

Rotating Wave Plate polarimeter

We have also build Stokes and Mueller polarimeters based on rotating wave plates.

  1. A. LizanaEstévez, I.Torres-Ruiz, F. A.Peinado, A.Ramírez, C., and Campos, J.“Arbitrary state of polarization with customized degree of polarization generator”, Opt. Lett., vol. 40, pp. 3790–3793, 2015.

Grating-based polarimeter

We have studied the performance of a complete snapshot polarimeter based on a polarization diffraction grating (PDGr) by using the usual quantitative metrics such as the conditional number. The PDGr is generated in a common path polarization interferometer with a Z optical architecture that uses two liquid-crystal on silicon (LCoS) displays to imprint two different phase-only diffraction gratings onto two orthogonal linear states of polarization.

  1. A. CofréVargas, A.Torres-Ruiz, F. A.Campos, J.Lizana, A.Sánchez-López, M. del M., and Moreno, I.“Quantitative performance of a polarization diffraction grating polarimeter encoded onto two liquid-crystal-on-silicon displays”, Optics & Laser Technology, vol. 96, pp. 219 - 226, 2017.
  2. A.VargasTorres-Ruiz, F. A.Campos, J.Donoso, R.Martínez, J. L., and Moreno, I.“Flexible polarimeter architecture based on a birefringent grating”, Applied Optics, vol. 53, pp. 5585-5592, 2014.
  3. I. MorenoCarrión, J. V.Martínez, J. L.García-Martínez, P.Sánchez-López, M. del M., and Campos, J.“Optical retarder system with programmable aspectral retardance”, Optics Letters, vol. 39, pp. 5483-5486, 2014.
  4. J. L. MartínezSánchez-López, M. del M.García-Martínez, P.Moreno, I., and Campos, J.“Programmable color tuning of a multiline laser by means of a twisted nematic liquid crystal display”, Applied Optics, vol. 51, pp. 6368-6375, 2012.
Campus d'excel·lència internacional U A B