Astigmatism compensation in optical instruments: applications and improvements in focimetry

• Autores: Sara Ferrer-Altabás
• Directores de la Tesis: Vicente Micó (dir. tes.)
• Lectura: En la Universitat de València ( España ) en 2025
• Idioma: español
• Tribunal Calificador de la Tesis: Walter Furlan (presid.), Amalia Lorente-Velázquez (secret.), José Manuel González-Méijome (voc.)
• Programa de doctorado: Programa de Doctorado en Optometría y Ciencias de la Visión por la Universitat de València (Estudi General)
• Materias:
  • Física
    • Óptica
      • Optometría
  • Ciencias tecnológicas
    • Tecnología de la instrumentación
      • Instrumentos ópticos
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• Resumen

  • This dissertation presents novel techniques applied to focimetry, mainly aiming at ophthalmic lens characterization, focusing on integrating tunable astigmatic devices into focimeters. Using vector-based dioptric power interpretation, it improves sphero-cylindrical power measurement accuracy, automation, and functionality. The research includes the design and validation of innovative methods, significantly advancing astigmatism measurement and ophthalmic instrumentation.

    Building on these foundations, the dissertation introduces vectofocimetry, a novel approach combining vector-based dioptric power interpretation with manual focimetry. This technique incorporates a modified Stokes lens into a manual focimeter, enabling simultaneous focus on both principal meridians of astigmatic lenses. Experimental validation demonstrated comparable accuracy to conventional focimeters while addressing traditional limitations. The integration of a fixed Jackson cross-cylinder extended measurement ranges without compromising precision.

    Further innovation led to the development of the liquid-lens focimeter, utilizing an electrowetting-controlled tunable liquid lens. This automated, objective system achieves simultaneous focus of both principal meridians via digital sharpness evaluation, addressing manual adjustment challenges. Validation confirmed performance comparable to commercial automatic focimeters while enabling functionalities like prismatic effect measurement and higher-order aberration analysis using the same lens element.

    The dissertation also adapts a manual focimeter for progressive lens inspection via shadowfocimetry, integrating holography into a manual focimeter embodiment to evaluate and marking laser-engraved marks in progressive lenses. These innovations extend focimeter capabilities while addressing challenges like manual adjustments and peripheral lens distortions.

    These advancements validate the potential of vector-based dioptric power interpretation as a foundation for future innovations in ophthalmic instrumentation. By integrating tunable devices and holography, the research achieves accurate, efficient measurements of astigmatism and spherical refractive errors, setting the stage for next-generation versatile focimetry.