Frequency domain (Wavelet) investigation of OCT images of skin

In this article we investigate the use of wavelet transform on the images produced by an optical coherence tomography (OCT) to obtain further information from the OCT images transformations in different levels of decomposition with two wavelet mother functions, in frequency domain. To transform the image from the spatial domain to the frequency domain, wavelet transformation of the image was used as it was found that the images obtained from the wavelet transform include more details than those obtained from Fourier transform. The OCT system employed for imaging was an en-Face time domain OCT which uses a dynamic focus scheme (Figure 1). With dynamic focus, the coherence gate is synchronised with the confocal gate; hence, the transverse resolution is conserved throughout the depth range and an enhanced signal is returned from all depths. Therefore, higher resolution images than those of standard OCT can be obtained. This OCT system is especially designed for use in applications where a high lateral resolution and a large depth range are required. The system uses a super luminescent diode (SLD) with a central wavelength of 1300 nm and a spectral bandwidth 54 nm.