Optical FRAME: Investigating the effects of filtering the optical Fourier domain to be used as a new approach for FRAME

Many important scientific phenomena require ultra-fast imaging to understand and investigate the characteristics of the event. Current methods of ultra-fast imaging that can obtain femtosecond time resolution rely on repeatable events or limiting the techniques versatility by completely remove the use of a dimension e.g. colour. FRAME is a novel technique which allows for ultra-fast imaging in the femtosecond regime for non-repeatable events without completely losing a dimension \cite{FRAME}. By superimposing a spatial modulation (tag) onto the illumination the beam of light can save information about an event. The tag is then decoded in post processing, thus gaining resolution in the tagged domain at the expense of the spatial resolution. In order to mitigate the spatial resolution reduction, this report present a new approach: Optical FRAME which performs the post-processing algorithm optically. The new approach is demonstrated to have similar spatial resolution results to its digital counterpart, thus proving it as a standalone approach. Furthermore, Optical FRAME's unique property of retagging the beam can be utilised to optimise the spatial resolution of the setup. This report confirms that this unique property can be exploited and used to benefit the viability of FRAME. Retagging is here used to achieve temporally resolved imaging along with a doubled spatial resolution in the final images. (Less)