Spatial and temporal spreading behaviors of light in glass particle-dispersed epoxy matrix composites evaluated by pico-
- PDF / 357,385 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 104 Downloads / 155 Views
The light diffusion behavior in a glass particle-dispersed epoxy matrix composite was evaluated using a pico-second order light pulse. Change in pulse profile was detected, and this change in different detection areas is discussed. The light scattering behavior in the composite was directly observed, and the result was compared with the pulse profile change. This change appeared in the pulse shape, and depended on the particle volume fraction and the area of light detected. The maximum probable light path extension and the light transmittance were strongly correlated with the direct observation result of spatial spreading behavior of light in the composite. The combination use of (i) maximum probable light path extension and (ii) light transmittance was effective in evaluating the light-scattering behavior of the composite. The method is applicable to evaluation of the light-scattering process in light-transmitting materials.
I. INTRODUCTION
Optical composites have been developed in the last decade and are believed to have properties that matrix materials never achieve.1–8 For example, packaging materials for near future optoelectronic devices require both low thermal expansion coefficient and high light transmittance at invisible and near-infrared wavelength range to transfer information through the packaging material; glass particle-dispersed polymer matrix composites are a strong candidate for such materials. Most studies on glass particle-dispersed polymer composites have focused on the designing procedure for better light transmittance. Effects of particle volume fraction,1,4 particle size,4,8 and the refractive index difference between matrix and the particle4,7 on the light transmittance have been reported. Composites with a maximum light transmittance, about 90% compared to pure polymer matrix, were achieved by selecting appropriate material systems.1 Optical properties of the glass particle-dispersed optical composites are usually evaluated by in-line and total light transmittances, which evaluate an integrated energy flux of the transmitted light.9 However, in addition to high light transmittance, the optical composites need high optical transparency, which is defined in this paper as straightly transmitting nonscattered light. The optical a)
Address all correspondence to this author. e-mail: [email protected]
2644
J. Mater. Res., Vol. 18, No. 11, Nov 2003
composites are required to read characters through them.10 However, the conventional methods are not sufficient to understand such the light-scattering behavior. The authors recently introduced a “time factor” into the evaluation of optical transparency and the scattering process in the optical composite. One approach is wave front measurement by detecting the phase shift with lateral shearing interferometers.11 Another approach is measurement of change in the light path by determining the flight time of light with a pico-second order (10−12 s) time-resolved light pulse technique. The time-resolved spectroscopic method with pico-second orde
Data Loading...
