6. Given that the line $l$ passes through the left focus $F$ of the ellipse $C: \frac{x^{2}}{2}+y^{2}=1$ and intersects the ellipse $C$ at points $A, B$, and $O$ is the origin. If $O A \perp O B$, then the distance from point $O$ to the line $A B$ is $\qquad$ .
From the second-order conclusion of the ellipse $\frac{1}{|O A|^{2}}+\frac{1}{|O B|^{2}}=\frac{1}{a^{2}}+\frac{1}{b^{2}}=\frac{3}{2}$, we can get
$$
\frac{3}{2}=\frac{|O A|^{2}+|O B|^{2}}{|O A|^{2}|O B|^{2}}=\frac{|A B|^{2}}{|O A|^{2}|O B|^{2}}=\frac{1}{d^{2}} \Rightarrow d=\frac{\sqrt{6}}{3} .
$$