Detection system for optical coherence tomography - Czerny - Turner spectrometer

Detection system for optical coherence tomography - Czerny - Turner spectrometer
Marcin Strąkowskia and Aleksandra Kamińskab
a,b Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications,
and Informatics, Gdańsk University of Technology, 11/12 Narutowicza, 80-233 Gdańsk, Poland

Optical coherence tomography (OCT) is a non-invasive method of investigation of internal structure of materials with micrometer resolution. It enables to obtain cross-sectional and three-dimensional visualizations of tested samples. This technique uses optical scanning beam and signal detection based on low-coherence interferometry. Nowadays, OCT is applied in medical diagnostics, especially in ophthalmology. However, development of this method enables it to be used in other, non-medical fields. Principally the systems based on signal processing in spectral domain (SD-OCT – Spectral Domain Optical Coherence Tomography) determine new development directions. This is due to the progress in speed of imaging in high resolution which makes OCT real-time systems.
The purpose of this paper is to describe optical design for high resolution spectrometer, which is a significant element of OCT system. Executed spectrometer records broadband optical radiation in the visible range (450 – 830 nm). Czerny – Turner configuration enables correction of astigmatism and coma aberration over full bandwidth. Moreover, spectrometer is characterized by uncomplicated construction. Merely two mirrors and diffraction grating allow to design low-cost spectrometer with satisfying optical properties. Spectrum detection has been executed using line scan camera with 6144 pixels. It provides high speed and resolution of the system.