Entangled-photon imaging of a pure phase object

Area of Science:

• Quantum optics
• Optical imaging
• Phase object characterization

Background:

• Coherent imaging typically requires spatially coherent illumination.
• Spatially incoherent light sources are often preferred for certain applications due to reduced speckle and cost.
• Phase objects are crucial in various scientific fields but challenging to image coherently with incoherent light.

Purpose of the Study:

• To demonstrate the possibility of obtaining a coherent image of a pure phase object using spatially incoherent illumination.
• To explore the use of entangled photons for phase imaging.
• To investigate the coherence properties of a two-beam source generated via spontaneous parametric down-conversion.

Main Methods:

• Experimental implementation using a microelectromechanical system (MEMS) micromirror array as the phase object.
• Theoretical analysis of the imaging process.
• Utilizing a two-beam source of entangled photons produced by spontaneous parametric down-conversion.
• Probing the phase object with one entangled beam while scanning the other.

Main Results:

• Successful acquisition of a coherent image of the pure phase object despite using spatially incoherent illumination.
• Experimental and theoretical validation of the imaging technique.
• Demonstration of higher-order interbeam coherence between the two entangled beams, even though individually they are spatially incoherent.

Conclusions:

• Coherent imaging of phase objects is achievable with spatially incoherent light by leveraging entangled photon pairs.
• The demonstrated technique offers a novel approach to phase imaging with potential applications in microscopy and metrology.
• Entangled photon sources provide a unique resource for overcoming limitations in conventional optical imaging.