K.B Gan - currently a Ph.D student in Deparment of Electrical, Electronik & System Engineering, Faculty Engineering, Universiti Kebangsaan Malaysia
E Zahedi - Associate Professor at School of Engineering SHARIF University of Technology, Iran
M. A Mohd Ali - Professor at Deparment of Electrical, Electronik & System Engineering, Faculty Engineering, Universiti Kebangsaan Malaysia

In this paper, safety aspects during optical investigation of the fetus are considered for wavelengths in the therapeutic window (600-1400 nm). Exposure limits for skin and eye are calculated based on the International Commission on Non-Ionizing Radiation Protection (ICNIRP). Results show that the exposure limit for the retina is 2.5 mW/cm2 (angular subtense < 1.5 milliradian) and 95.3 mW/cm2 (angular subtense > 1.5 milliradian) whereas for the skin it is 502 mW/cm2. Simulation results show that a 3500 W light source is needed in order to achieve fetus eye exposure limit as stated in ICNIRP. Limiting light power to 502 mW/cm2 (equivalent to a 48 mW light source at 3.5 mm diameter aperture) will ensure fetal eye safety while the mother’s skin is also protected from burns.