title: Index mismatch aberration correction over long working distances using spatial light modulation.
abstract: For many microscopy applications, millimeters-long free working distances (LWD) are required. However, the high resolution and contrast of LWD objectives operated in air are lost when introducing glass and/or liquid with the sample. We propose to use spatial light modulation to correct for such beam aberrations caused by refractive index mismatches. Focusing a monochromatic laser beam with a 10 mm working distance air objective (50×, 0.5 NA) through air, glass, and water, we manage to restore a sharp, intense focus (FWHM<2λ) by adaptive beam phase shaping. Our approach offers a practical and cost-effective route to high resolution and contrast microscopy using LWD air objectives, extending their usage beyond applications in air.
authors.affiliation: FOM Institute AMOLF, Science Park 104, Amsterdam 1098 XG, The Netherlands.
authors.forename: Bergin
authors.initials: B
authors.lastname: Gjonaj
authors.forename: Patrick
authors.initials: P
authors.lastname: Johnson
authors.forename: Mischa
authors.initials: M
authors.lastname: Bonn
authors.forename: Katrin F
authors.initials: KF
authors.lastname: Domke