  Based on the difference between mean background of an optical sample
refractive index n_0 and an outside medium, n_out, different than n_0, we study
the reflection statistics of a one-dimensional weakly disordered optical medium
with refractive index n(x)=n_0+dn(x). Considering dn(x) as color noise with the
exponential spatial correlation decay length l_c and k as the incident wave
vector, our results show that for the small correlation length limit, i.e.
k*l_c<1, the average value of reflectance, r, follows a form that is similar to
that of the matched refractive-index case n_0=n_out, i.e., <r(dn, lc)>
proportional to <dn^2>l_c. However, the standard deviation of r is proven to be
std(r(dn,l_c)) proportional to sqrt(<dn^2>l_c), which is different from the
matched case. Applications to light scattering from layered media and
biological cells are discussed
