Terahertz optical setups using spatial filtering methods to image low-absorbing samples

Adrianna Nieradka; Paweł Komorowski; Mateusz Kaluza; Mateusz Surma; Agnieszka Siemion

doi:10.1117/12.3017683

18 June 2024 Terahertz optical setups using spatial filtering methods to image low-absorbing samples

Adrianna Nieradka, Paweł Komorowski, Mateusz Kaluza, Mateusz Surma, Agnieszka Siemion

Proceedings Volume 12994, Terahertz Photonics III; 129940E (2024) https://doi.org/10.1117/12.3017683
Event: SPIE Photonics Europe, 2024, Strasbourg, France

Abstract

The fast development of terahertz (THz) technology holds significant importance in numerous applications where imaging systems are indispensable. Moreover, advanced imaging systems increasingly demand the capability to image transparent objects. This is particularly challenging due to the relatively low efficiency of THz sources, leading to low power in THz systems. Additionally, parasitic reflections in mostly very coherent THz optical systems result in the occurrence of high speckle noise. One of the solutions for the enhancement of the imaging contrast of transparent objects is the application of spatial filtering (SF) methods in the system, which we implement here via the following methods: positive phase contrast (PPC), negative phase contrast (NPC), and dark field (DF). In this study, the authors report the implementation of all three methods in the 4f THz system for relatively long-distance imaging of 1200 mm. The system was tested with the numerical simulation. The detailed analysis of the results allowed for the selection of the recommended size of the spatial phase filter for the implementation of the SF methods in the experimental optical setup. The filter and the object were manufactured using fused deposition modeling (FDM) 3D printing technology. Subsequently, the 4f system facilitating the SF methods was built and examined experimentally. The analysis of the experimental results indicates the enhancement of the signal-to-noise ratio (SNR) by almost 14 times with the use of the PPC method compared to the system without the inserted filter. Thus, the improvement of the image contrast by the implementation of SF method is unquestionable.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Adrianna Nieradka, Paweł Komorowski, Mateusz Kaluza, Mateusz Surma, and Agnieszka Siemion "Terahertz optical setups using spatial filtering methods to image low-absorbing samples", Proc. SPIE 12994, Terahertz Photonics III, 129940E (18 June 2024); https://doi.org/10.1117/12.3017683

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