Spectrum multiplexing and coherent-state decomposition in Fourier ptychographic imaging (1405.0220v1)

Published 1 May 2014 in physics.optics

Abstract: Information multiplexing is important for biomedical imaging and chemical sensing. In this paper, we report a microscopy imaging technique, termed state-multiplexed Fourier ptychography (FP), for information multiplexing and coherent-state decomposition. Similar to a typical Fourier ptychographic setting, we use an array of light sources to illuminate the sample from different incident angles and acquire corresponding low-resolution images using a monochromatic camera. In the reported technique, however, multiple light sources are lit up simultaneously for information multiplexing, and the acquired images thus represent incoherent summations of the sample transmission profiles corresponding to different coherent states. We show that, by using the state-multiplexed FP recovery routine, we can decompose the incoherent mixture of the FP acquisitions to recover a high-resolution sample image. We also show that, color-multiplexed imaging can be performed by simultaneously turning on R/G/B LEDs for data acquisition. The reported technique may provide a solution for handling the partially coherent effect of light sources used in Fourier ptychographic imaging platforms. It can also be used to replace spectral filter, gratings or other optical components for spectral multiplexing and demultiplexing. With the availability of cost-effective broadband LEDs, the reported technique may open up exciting opportunities for computational multispectral imaging.

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Summary

Spectrum Multiplexing and Coherent-State Decomposition in Fourier Ptychographic Imaging

The paper authored by Siyuan Dong, Radhika Shiradkar, Pariksheet Nanda, and Guoan Zheng examines an innovative microscopy imaging technique known as state-multiplexed Fourier ptychography (FP). The primary objective of this technique is to enhance information multiplexing and facilitate coherent-state decomposition within Fourier ptychographic imaging. Recognizing the limitations of existing FP techniques, which primarily rely on a single coherent state of the light source, this paper proposes a significant advancement: the introduction of multiple simultaneous light sources for sample illumination to manage incoherent summations of transmission profiles corresponding to different coherent states.

Synopsis of the Proposed Technique

The authors detail how state-multiplexed FP diverges from conventional FP methods by integrating multiple light sources concurrently. As such, they achieve information multiplexing by generating a mosaic of low-resolution images, each capturing information from varied coherent states. The crucial innovation lies in the recovery routine, which adeptly decomposes these incoherent mixtures to reconstruct a high-resolution sample image. Moreover, this approach is expanded to color-multiplexed imaging, where RGB LED lights are employed concurrently, demonstrating the versatility of the technique.

Simulations and Experimental Validation

Simulations conducted to investigate the efficacy of the state-multiplexed FP provide compelling evidence. When two adjacent LED elements are lit simultaneously, the algorithm effectively recovered high-resolution intensity and phase images with minimal mean-square errors. The mean-square error metrics for the intensity reconstructions were notably similar to traditional single-state techniques, substantiating the model’s accuracy and reliability.

In laboratory experiments, particularly with pathology slides, the novel scheme proved successful. Conditions included simultaneous illumination using RGB LED arrays, which were used to acquire low-resolution images that represented summed sample profiles across different wavelengths. High-resolution reconstructions were achieved, demonstrating coherence between the simulation outcomes and practical application.

Implications and Future Directions

The implications of this research could substantially influence both practical applications and theoretical developments in imaging technologies. The proposed methodology for state-multiplexed FP offers a promising alternative to conventional spectral filters and optical components, potentially reducing reliance on complex hardware setups and expanding the capabilities for spectral multiplexing. Additionally, this approach offers a straightforward solution to model partially coherent effects, accommodating varied light source characteristics regarding spatial and temporal coherence.

The authors acknowledge inherent limitations within their method, particularly concerning intensity uncertainties of the LED arrays, which contribute to reconstruction errors. Future research might address these issues, fostering improved calibration techniques or alternative light pattern configurations to elevate acquisition and illumination standards.

This exploration suggests pathways for computational multispectral and hyperspectral imaging with implications for cost-effectiveness and accessibility. Furthermore, the noted connection to compressive sensing techniques raises the potential for constrained acquisition procedures and decreased photon budgets. It invites further investigation into leveraging optimal basis patterns and evaluating the interplay between data redundancy and compressibility, which is pivotal for advancing imaging systems.