Spectral attenuation of brain and retina tissues in the near‐infrared range measured using a fiber‐based supercontinuum device

Abstract

A novel setup for the efficient constant optical measurements of biological tissues in the near infrared is presented. The system combines the use of a fiber-based supercontinuum source with a simple optics fiber collimator. This configuration allows a wide spectral range of measurement and, at the same time, can efficiently filter the straightforward transmitted light while avoiding scattered light. As a performance example, the optical characterization of rat brain and retina tissues are shown. The attenuation coefficient for both tissues in the near infrared region is also obtained. This technique could be applied in clinical research as a noninvasive method with several potential practical applications.

Measurement method of optical properties of ex vivo biological tissues of rats in the near-infrared range

“…Recently, supercontinuum sources have been used to quantify transmission spectra in the IR range through several ex vivo rat tissues. Thus, it has been described that the spectral attenuation in the spleen, kidney, heart, retina, and brain fell off quickly for longer wavelengths [17,18], suggesting that similar behavior can be found in any kind of biological tissues, even blood [6], which results in a lower attenuation for longer wavelengths. The optical properties of tissue have a strong dependence on wavelength, and it is necessary to choose the proper wavelength to achieve a large penetration depth.…”

“…The supercontinuum source [Fig. 1(b)] was the same as those of Saldaña et al [18]. A passive mode-locked ring laser (PMLRL) produced a train of femtosecond pulses, which were used as a seed for a highly nonlinear fiber (HNLF) to obtain a supercontinuum spectrum.…”

“…The transmittance of different tissues was measured by means of the previously described single-mode fiber collimator based on a graded-index lens [18]. Since the acceptance angle of the gradient-index lens is very small (0.15 deg.…”

“…However, the actual procedure is not so easy. Although α is measured using the method based on fiber collimators [18], the values of k a and k s cannot be determined, but can only be delimited between the maximum and minimum values. By means of Eq.…”

Highly coherent flat supercontinuum generation in highly nonlinear silica fiber pumped by 1.5μm femtosecond fiber laser

“…Supercontinuum (SC) light sources exhibiting excellent wide bandwidth and good beam quality have attracted much attention because of their potential applications including spectrum [1,2], optical communication [3][4][5], optical coherence tomography[6-8], environmental monitoring [9,10], medical treatments [11,12], as well as defense and security [13]. To date, SC generation based on optical bers continues to be an active topic of research, researchers are devoted to improving the various performance parameters of SC spectrum, such as higher output power, wider spectral bandwidth, and better spectral atness.…”