Extending the Depth of Focus of an Infrared Microscope Using a Binary Axicon Fabricated on Barium Fluoride

• Published in: Micromachines (Basel) Vol. 15; no. 4; p. 537
• Main Authors: Han, Molong, Smith, Daniel, Kahro, Tauno, Stonytė, Dominyka, Kasikov, Aarne, Gailevičius, Darius, Tiwari, Vipin, Ignatius Xavier, Agnes Pristy, Gopinath, Shivasubramanian, Ng, Soon Hock, John Francis Rajeswary, Aravind Simon, Tamm, Aile, Kukli, Kaupo, Bambery, Keith, Vongsvivut, Jitraporn, Juodkazis, Saulius, Anand, Vijayakumar
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.04.2024
• Subjects: axial resolution; Background noise; Barium; Barium fluorides; binary axicon; chemical imaging; Depth of field; Experiments; femtosecond ablation; Fluorides; infrared microscopy; Light; photolithography; Sensors; Substrates; Germany; binary axicon; chemical imaging; femtosecond ablation; photolithography; axial resolution; infrared microscopy
• ISSN: 2072-666X; 2072-666X
• DOI: 10.3390/mi15040537

Axial resolution is one of the most important characteristics of a microscope. In all microscopes, a high axial resolution is desired in order to discriminate information efficiently along the longitudinal direction. However, when studying thick samples that do not contain laterally overlapping information, a low axial resolution is desirable, as information from multiple planes can be recorded simultaneously from a single camera shot instead of plane-by-plane mechanical refocusing. In this study, we increased the focal depth of an infrared microscope non-invasively by introducing a binary axicon fabricated on a barium fluoride substrate close to the sample. Preliminary results of imaging the thick and sparse silk fibers showed an improved focal depth with a slight decrease in lateral resolution and an increase in background noise.