What are the advantages of ghost imaging? Multiplexing for x-ray and electron imaging

Abstract

Ghost imaging, Fourier transform spectroscopy, and the newly developed Hadamard transform crystallography are all examples of multiplexing measurement strategies. Multiplexed experiments are performed by measuring multiple points in space, time, or energy simultaneously. This contrasts to the usual method of systematically scanning single points. How do multiplexed measurements work and when they are advantageous? Here we address these questions with a focus on applications involving x-rays or electrons. We present a quantitative framework for analyzing the expected error and radiation dose of different measurement scheme that enables comparison. We conclude that in very specific situations, multiplexing can offer improvements in resolution and signal-to-noise. If the signal has a sparse representation, these advantages become more general and dramatic, and further less radiation can be used to complete a measurement.

Writing arbitrary distributions of radiant exposure by scanning a single illuminated spatially random screen

“…This question is related to, but distinct from, that of rasterscanning versus multiplexing in ghost imaging [1,12,66] and spectroscopy [66,67]. Both ghost imaging and spectroscopy have regimes in which there is an advantage to multiplexing, such as the Fellgett advantage for spectroscopy [67] or the multiplex advantage for the imaging of sparse objects using ghost imaging [66]. Analogous regimes are likely to exist for the work of the present paper.…”

“…Depending on the precise properties of the noise processes involved in both illumination and substrate response to applied radiant exposure, there can be an advantage in multiplexed exposure strategies compared to raster scanning. This question is related to, but distinct from, that of rasterscanning versus multiplexing in ghost imaging [1,12,66] and spectroscopy [66,67]. Both ghost imaging and spectroscopy have regimes in which there is an advantage to multiplexing, such as the Fellgett advantage for spectroscopy [67] or the multiplex advantage for the imaging of sparse objects using ghost imaging [66].…”

Mapping photocathode quantum efficiency with ghost imaging

“…Cathode QE ghost imaging holds promise for electronsource based user facilities where dedicated time to study the performances of the injector is limited, and the spatial variation of the QE is a critical quantity affecting the final beam brightness and machine performance. More generally, we believe ghost imaging can be a valuable tool at accelerators, where noisy probes are common and opportunities for dedicated studies are limited [15,27]. The ghost imaging philosophy of "measurement is easier than control" can find applications for a wide range of accelerator problems.…”

“…Finally, and crucially for QE mapping, the ghost imaging framework can use the intrin-sic noise in the illumination pattern of the photocathode drive laser to implement a passive measurement method that avoids disturbing normal operation. See [15] for a summary of the advantages of multiplexing.…”

Temporal power reconstruction for an x-ray free-electron laser using convolutional neural networks

“…The femtosecond scale is critical for studies in protein nanocrystallography damage [2][3][4], matter under extreme conditions [5], atomic, molecular, and optical physics [6][7][8][9], chemical reactions [10], and more. While standard pump-probe experiments are limited in resolution by the minimum duration of the x-ray pulse, knowledge of the temporal power-profile shot-by-shot enables time resolution even shorter than the pulse length [11]; taking an approach of measuring rather than controlling opens the window to both higher time resolution and easier operating conditions [12]. Moreover, pulse length measurements are critical both for development and setup of short pulse modes (see, e.g., [13][14][15][16]).…”