Optical-sectioned images with super-resolution enhancement is achieved by combining the information in data obtained from a tunable structured illumination microscope. The system can easily switch between two fringe patterns required for optical sectioning and super-resolution. OCIS codes: (110.1758) Computational Imaging; (180.6900) Three-dimensional Microscopy; (100.6640) Super-resolution. 1. Introduction Conventional structured illumination microscopy (SIM) systems [1]-[3], can only produce two-dimensional (2D) patterns, which are not able to provide simultaneously the highest improvement in both the lateral and axial resolution. In fact, the performance of 2D-SIM depends on the modulation frequency of the illumination pattern; this value determines the resolution enhancement either laterally or axially [4]. To provide resolution enhancement in three dimensions, a three-dimensional (3D) structured pattern that includes both lateral and axial variations in the excitation illumination is required [5]. Gustafsson et al. [5] used three-wave (3W) interference to produce an interference pattern that modulates the object at two different lateral frequencies; the highest modulation frequency provides super-resolution performance while the lower modulation frequency, whose value is exactly equal to half of the highest modulation frequency, produces optical sectioning capability. However, these two modulation frequencies are fixed by the illumination system and they are completely dependent on each other; as a result there is no flexibility in choosing two independent different modulation frequencies. Here, we address the resolution enhancement's issue in 3D by using a 2D-SIM system whose modulation frequency is easily adjustable. In this tunable-frequency SIM system [6,7], a Fresnel biprism is illuminated by a wavefront emerging from one incoherent linear source (e.g. a slit) and it produces an axially-extended pattern in which the modulation frequency changes with the location of the Fresnel biprism along the optical axis. In this contribution, we present a computational method that takes advantage of the tunable-frequency SIM by recording phase-shifted images for two independent modulation frequencies (three images for each frequency of the same field of view). The lower spatial modulation frequency provides the optical sectioning (OS) capability by filling the missing cone and the other one produces super-resolution (SR) performance by almost doubling the cutoff frequency (í µí± ") of the conventional wide-field system. Combining information from two different datasets has been used in other applications such as in the HiLo imaging system [9] and in by the FABEMD algorithm [10]. The former uses uniform and speckle illumination to produce OS with a resolution comparable to deconvolution microscopy (i.e. without SR), and the latter is a double-shot SIM to generate an OS image without SR. Our method combines the information in the six intermediate SIM images and provides simultaneous OS and SR in the reconstructed 3D...
