1. Inverse-designed 3D laser nanoprinted phase masks to extend the depth of field of imaging systems
- Author
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Sturges, T. J., Nyman, M., Kalt, S., Pälsi, K., Hilden, P., Wegener, M., Rockstuhl, C., and Shevchenko, A.
- Subjects
Physics - Optics - Abstract
In optical imaging, achieving high resolution often comes at the expense of a shallow depth of field. This means that when using a standard microscope, any minor movement of the object along the optical axis can cause the image to become blurry. To address this issue, we exploit inverse design techniques to optimise a phase mask which, when inserted into a standard microscope, extends the depth of field by a factor of approximately four without compromising the microscope's resolution. Differentiable Fourier optics simulations allow us to rapidly iterate towards an optimised design in a hybrid fashion, starting with gradient-free Bayesian optimisation and proceeding to a local gradient-based optimisation. To fabricate the device, a commercial two-photon 3D laser nanoprinter is used, in combination with a two-step pre-compensation routine, providing high fabrication speed and much better than subwavelength accuracy. We find excellent agreement between our numerical predictions and the measurements upon integrating the phase mask into a microscope and optically characterising selected samples. The phase mask enables us to conduct simultaneous multiplane imaging of objects separated by distances that cannot be achieved with the original microscope.
- Published
- 2024