Developments on Using Supercontinuum Sources for High Resolution Multi-Imaging Instruments for Biomedical Applications

We report on further progress made on enhancing the capabilities of a multi-imaging modality instrument capable of producing high resolution images of biological tissues. At the core of the instrument is a supercontinuum (SC) source. Two SC sources commercialized by NKT Photonics were employed for our experiments: SuperK COMPACT and SuperK Extreme (EXR9). Using these two sources, we assembled an instrument capable to simultaneously provide in real-time cross-section high-resolution Optical Coherence Tomography (OCT) and Photo-acoustic (PA) images in various spectral ranges. Currently, the OCT channel is operating in the IR range around 1300 nm to allow better penetration into the tissue using either the COMPACT or the EXR9. The measured optical power on the sample is in both cases above 9.5 mW. An in-house spectrometer equipped with a sensitive InGaAs camera capable of operating at 47 kHz and sampling data over a spectral range from 1205 to 1395 nm was developed. A constant axial resolution provided by the instrument in the OCT channel over a range of 1.5 mm was experimentally measured (4.96 µm), matching the theoretical prediction. The spectral range 500-800 nm was used for PA channel. The COMPACT, used in the PA channel, can select the central wavelength and the spectral bandwidth of operations. Typically, the optical energy per pulse on the sample is superior to 60 nJ when a bandwidth superior to 50 nm is employed. This make the instrument usable for PA imaging of tissues.