High-visibility ghost imaging by holographic projection with classical light

TL;DR

The paper addresses improving ghost imaging visibility with classical light by leveraging computational holography to realize the super-bunching effect, achieving a peak-to-background ratio of $39.77$. It introduces holographic projection GI and uses second-order intensity correlations, with $g^{(2)}(x)=\\frac{\\langle \\mathcal{RS}(x)\\\\mathcal{TS} \\rangle}{\\langle \\mathcal{RS}(x) \\rangle \\langle \\mathcal{TS} \\rangle}$ and $V=\\frac{g^{(2)}_{max}-g^{(2)}_{min}}{g^{(2)}_{max}+g^{(2)}_{min}}$ to quantify image quality. It also maps data sources for thermal GI and holographic projection GI, and introduces reconstruction-pattern and target-pattern signals (RP/TP) along with abbreviations for the simulated, experimental, and RS/TS data (e.g., Sim-SP, Exp-RP, CHGI-\\mathbb{R}, CHGI-\\mathbb{T}). Five GI schemes are demonstrated, including EHGI, CHGI, and SHGI variants with reconstruction-pattern and target-pattern signals, with SHGI schemes delivering the highest visibility, especially when the TP is derived from a sparse matrix. The flexible TP design enables both positive and negative ghost copies and broadens the correlation-algorithm toolbox for practical high-visibility GI with classical light.

Abstract

By adopting computational holography, we realized the super-bunching effect achieving the peak-to-background ratio 39.77 proposed in the article [arXiv:2510.20421v1]. In this paper, various reference signals from computational holography and corresponding bucket detection signals are used in the intensity correlation algorithm of ghost imaging (GI) scheme. In the experiment, we use two types of target patterns, intensity squared chaotic speckle and artificially designed sparse matrix, performing GI by holographic projection. Those imaging results show that the visibility of ghost image can be significantly improved whether the reference signal is the reconstruction pattern or the target pattern of computational holography. Furthermore, we realize positive and negative copies of ghost image by the aid of computational holography in which symmetrical target patterns are artificially designed. Thus, our study by means of computational holography not only presents a step toward meeting the visibility requirement for practical applications but also broadens the category of intensity correlation algorithm of classical light GI scheme.

Figures (7)

• Figure 1: Generation processes of reference signals (a) and test signals (b) in thermal light GI (shown by red solid line boxes) and holographic projection GI (shown by blue solid line boxes) are represented by a flow diagram. TP: target pattern; GS: Gerchberg-Saxton algorithm, CGH: computer-generated holograms; HF: Huygens-Fresnel principle; CCD: charge coupled device. (c) and (d) are the correspondence between the abbreviations of GI scheme and data sources of intensity correlation in thermal light GI and holographic projection GI, respectively. TS: test signal; RS: reference signal. See text for explanation of abbreviations on various reference signals, test signals and GI schemes.
• Figure 2: Schematic diagram of the experimental setup for the ghost image scheme. BE: beam expander; BS: 50:50 beam splitter; SLM: phase-only spatial light modulator; CCD: charge coupled device. $f$ is the focal length of the Lens. A letter "N" was served as an input object, placing at the central of the object plane of the $2f-2f$ imaging system.
• Figure 3: Simulated or experimental results of ghost image with chaotic source according to three GI schemes: (a) SGI, (b) CGI and (c) TGI, respectively. The visibility $V$ of ghost image are displayed in the bottom right corner of the subgraphs. Three subgraphs share a common color bar.
• Figure 4: Simulated or experimental results of ghost image by holographic projection with the TP originated from the intensity squared speckle according to five GI schemes: (a) SHGI-$\mathbb{R}$, (b) CHGI-$\mathbb{R}$, (c) EHGI-$\mathbb{R}$, (d) CHGI-$\mathbb{T}$ and (e) SHGI-$\mathbb{T}$, respectively. The visibility $V$ of ghost image are displayed in the bottom right corner of the subgraphs. Five subgraphs share a common color bar.
• Figure 5: Five kinds of simulated or experimental holographic projection GIs with different sparsity parameter $p$. The visibility $V$ of ghost image are displayed in the bottom right corner of the subgraphs. To effectively display the imaging results, five subgraphs horizontally arranged with same parameter $p$ share a common color bar.