Ghost Imaging of Biological Samples Using Non-Degenerate Entangled Photons
Duncan P. Ryan1* (firstname.lastname@example.org), Kristina A. Meier1, Peter M. Goodwin1, David C. Thompson1, Rebecca H. Sandoval1, Raymond T. Newell1, Demosthenes P. Morales1, Kati A. Seitz2, David Hanson2, Scott N. Twary1, and James H. Werner1
1Los Alamos National Laboratory; and 2University of New Mexico
This project aims to image plants using noninvasive and nondisruptive methods. Using entangled photons, plant samples will be probed with near-infrared photons (NIR), but an image will be generated with visible photons that never interacted with the sample in an approach called ghost imaging. This method will measure the NIR absorption of plant matter for chemical composition without requiring the introduction of fluorescent probes. The advantage of ghost imaging is that the plant will experience extremely low light flux from the probing photons, leaving the organism completely undisturbed.
Studying dynamic processes in plants using optical techniques is challenging because plants are sensitive to visible light. For example, camelina and sorghum are two species that are drought tolerant and have high economic values. However, water redistribution within these plants during various growth phases is difficult to measure without disturbing the ongoing biological processes. As photosynthesis is active when plants are illuminated with visible light, the process of probing plants inherently induces an undesirable response. The team reports on efforts to image plants in the near-infrared (NIR) region of the spectrum where chemical signatures can inform about the distribution of specific biomasses such as water, lipids, and lignocellulose.
While most common techniques in the NIR (i.e., FT-IR and Raman spectroscopy) involve high photon fluxes to measure chemical signatures, team members are pursuing ghost imaging to ameliorate any potential disruption to the functions of the plants. Ghost imaging involves generating photon pairs that are spatially and temporally correlated. One photon of a pair is used as a probe to be absorbed or transmitted through a living plant. The other photon is sent along a different optical path to be detected by an imaging device that records the spatial origins of the photon. By correlating the photons that are transmitted though the plant with those that arrive on the imaging detector, an absorption image can be formed with extremely low light flux. Furthermore, the two photons of a pair can be different wavelengths, allowing the plant to be probed in the NIR, but the image formation is in the visible. Ghost imaging is challenging because of the requirements on the imaging detector. Common scientific cameras cannot operate at high enough frame rates to perform the correlation, and other detector technologies, such as single-photon avalanche photodiode arrays (SPAD array), have not reached maturity for their application to these types of imaging experiments.
Team members demonstrate the application of a low-light imager, Nocturnal Camera (NCam), to ghost imaging for biological research. NCam is capable of recording single-photon arrivals with the spatial and temporal resolution to perform ghost imaging. Specific details about the design of a microscope based on ghost imaging with NCam will be presented as well as the most recent results from imaging experiments.
Los Alamos National Laboratory is managed by Triad, LLC for the U.S. Department of Energy under contract no. 89233218CNA000001. The Center for Integrated Nanotechnologies is supported under contract no. 89233218CNA000001. This research was supported by the DOE Office of Science, Office of Biological and Environmental Research (BER), grant no. 0000253585. LA-UR #23-21451.