Microsphere-assisted digital holographic microscopy integrated with on-line thermal lens spectrometry for 3D imaging and enhanced photothermal detection

Abstract

Acquiring morphological and photothermal information is essential for characterization of a variety of samples in biochemistry, material science and process technologies. In this paper, we report on the integration of digital holographic microscopy (DHM) and thermal lens (TL) spectrometry techniques enabling simultaneous measurement of both class of properties: morphological images and photothermal parameters. DHM in transmission mode is an effective technique for label-free, non-contact, real-time, and non-invasive imaging and measurement of phase objects, such as biomaterials. On the other hand, TL is a highly sensitive methodology to detect low concentrations of analytes in low absorbing samples. We demonstrate the usefulness of the DHM-TL integrated system by applying it to obtain morphometrical information of samples as well as for acquisition of their photothermal maps. Further, by extending the concept of “microsphere-assisted (MS) imaging” into TL, we show that MS-TL enables detection and counting of particles, which otherwise their photothermal signals cannot be detected. The system has the potential to be applied for a variety of objects including bio-samples and may be proposed as a bench-top characterization device.