Shaping light plays a crucial role in science and technology, enabled by advancements in spatial-light modulator (SLM) technology. In this talk, we will explore two key applications: WFS microscopy for deep tissue imaging and holographic displays.
In the first part, we will discuss wavefront shaping systems and how they enable deep tissue imaging by correcting aberrations caused by tissue inhomogeneity. However, estimating optimal modulations remains challenging due to unknown tissue structures. Most current techniques employ slow coordinate descent algorithms, which sequentially scan all modulation elements and query their values independently. Thus, their complexity scales prohibitively with the number of modulation parameters. We present a rapid wavefront shaping method that transitions from coordinate to gradient descent optimization, simultaneously updating all modulation parameters. Our approach employs a non-invasive, guide-star-free score function to quantify modulation effectiveness.
We derive an analytical framework expressing the score’s gradient with respect to all parameters. Although this gradient depends on the unknown tissue structure, we demonstrate how it can be inferred from optical measurements. This method enables rapid computation of high-resolution wavefront corrections required for thick tissue samples, with complexity independent of the number of modulation parameters. Finally, we demonstrate our framework’s efficacy in correcting aberrations in a coherent confocal microscope.
In the second part, we explore holographic displays and their limitation: etendue. Etendue is defined as the product of the display’s size and angular range, which is bounded by pixel count. Current SLMs are inadequate for realistic displays, needing far more pixels. Existing strategies for etendue expansion use a diffractive optical element (DOE), whose pitch is smaller than that of the SLM, thereby spreading light over a wider angle. However, a fixed phase mask does not increase degrees of freedom, resulting in loss of image quality. We study the trade-offs of static phase masks for etendue expansion. We characterize what trade-offs are involved, and how specific phase mask design could support better holograms.
Next, we suggest expanding the etendue by augmenting the pixel with tilting capabilities. We show that tiltable displays can be realized using a cascade of binary tilt layers, each capable of tilting the light towards one of two orientations. We implement a proof-of-concept display and demonstrate its applicability for displaying multi-view or holographic content with increased size and angular field-of-view.
Sagi Monin is a Ph.D. student under the supervision of Prof. Anat Levin . His research focuses on computational photography, wavefront-shaping for microscopy. and holographic displays.
He received the Jacobs-Qualcomm scholarship, the Sherman scholarship, the Boaz Porat award, and Meyer excellence award.
PhD student under the supervisor of Prof. Anat Levin
