Experimental Assessment of a Compact Four-Hololens Imaging System Using Holographic Lenses from Glass and Emulsion Sides for In-Plane Displacement Measurement

Arasad Ali Khan

Coherent imaging, Double-exposure, Holographic lenses, In-plane displacement, Speckle metrology.

To achieve diffraction-limited imaging over extended objects with negligible monochromatic aberrations, coherent imaging systems based on two identical holographic lenses in a conjugate arrangement have gained considerable attention in speckle metrology. However, the measurement sensitivity, defined as the minimum measurable in-plane displacement of a two-hololens system, is limited by the f-number of the holographic lenses. To overcome the dependency of measurement sensitivity on f-number of holographic lenses, the use of a double-aperture four-hololens system is investigated. Holographic lenses are employed from both emulsion and glass sides in the four-hololens system. Experiments were performed using holographic lenses recorded with a typical f-number of 7.1 and inter-beam recording angles of 11° and 18° between the plane and spherical recording beams. The experimental results demonstrate that holographic lenses recorded with a larger inter-beam recording angle provide high measurement sensitivity, while the use of holographic lenses from emulsion and glass sides has no significant effect on the in-plane displacement measurement. Furthermore, employing holographic lenses on both the emulsion and glass sides facilitates the easy alignment of the holographic lenses within the four-hololens system.

Received: 09 June 2026, Received in revised form: 05 July 2026, Accepted: 11 July 2026, Available online: 16 July 2026

10.22161/ijaers.137.3