Maskless imaging of dense samples using pixel super-resolution based multi-height lensfree on-chip microscopy

Area of Science:

• Microscopy
• Optical Imaging
• Biomedical Engineering

Background:

• Lensfree in-line holographic microscopy provides sub-micron resolution over a large field-of-view (~24 mm2).
• This technique is limited to low-density samples, restricting its application.
• A cost-effective and compact design makes it suitable for field use.

Purpose of the Study:

• To overcome the density limitation of lensfree holographic microscopy.
• To enable imaging of dense and connected specimens over a large field-of-view.
• To develop an on-chip imaging approach for improved sample analysis.

Main Methods:

• Utilized pixel super-resolution and phase recovery techniques.
• Iterated multiple lensfree intensity measurements with varying sample-to-sensor distances.
• Digitally aligned and registered intensity measurements for reconstruction.

Main Results:

• Successfully reconstructed phase and amplitude images of dense specimens.
• Achieved imaging over a large field-of-view (~24 mm2) without spatial masks.
• Demonstrated the approach on dense Papanicolaou (Pap) smears and blood samples.

Conclusions:

• The multi-height in-line holographic approach effectively images dense samples.
• This method expands the applicability of lensfree microscopy for field diagnostics.
• The technique offers a mask-free solution for high-resolution imaging of complex biological samples.