This will count as one of your downloads.
You will have access to both the presentation and article (if available).
In conventional systems, such as bright field microscopy, a three-dimensional representation of particles is rather difficult, as it is challenging to acquire depth information about the sample. Quantitative phase imaging techniques provide phase and amplitude and thus in-depth information. Furthermore, they offer single shot measurements while providing images from multiple focal planes. Concerning the stability, which is an important aspect in localizing particles of diffraction limited size, common-path digital holographic microscopy is a reliable tool in particular in combination with a self-referencing system.
In this article, we show a common-path digital holographic microscope for particle localization. Firstly, the setup is characterized with a test chart in order to evaluate lateral and axial resolution properties. Afterwards a sample with particles distributed in a three-dimensional medium is analyzed. For reconstruction of the holograms, we use the angular spectrum method, numerical phase unwrapping as well as Zernike polynomials for aberration correction. All in all, the system is able to achieve stable particle localization in 3D with lateral resolution in the sub-micrometer range and an axial sensitivity of at least 100 nm.
In order to assess the strength of the transducer influence at short delay times and develop data analysis procedure, we investigate the photoacoustic responses of a phantom sample to double-pulse excitation measured with different transducers. Both focused and flat surface single element transducers are used in the study. The central frequencies are chosen in the low-frequency band as they are most widely used in clinical ultrasound and one higher frequency transducer is taken for comparison.
Despite not observing signal amplification due to Grueneisen relaxation effect, we show that transducer influence is not exceeding measurement error. Additionally we prove that single pulse subtraction procedure can be used to restore the second pulse waveform in double pulse excitation scheme. We believe using this procedure can be beneficial when transducer’s waveform duration is longer than used inter-pulse delays.
In this contribution we propose a compact low cost lensless digital holographic microscope capable of performing measurements on reflective microstructures. The novelty of the system consists on a direct use of a laser diode without any need of coupling optics as light source. This simplifies the setup and provides sufficient magnification to measure microstructures. We evaluate our setup by imaging reflective microstructures. We have achieved ̴ 6 mm2 field of view amplitude images with ̴ 2.5μm lateral resolution and phase images with axial resolution in nanometer range. The phase image provides a full-field profile measurement of the sample in nanometer range.
View contact details
No SPIE Account? Create one
