  The proton-proton momentum correlation function is constructed in three-body
photo-disintegration channels from $^{12}$C and $^{16}$O targets in the
quasi-deuteron regime within the framework of an extended quantum molecular
dynamics model. Using the formula of Lednicky and Lyuboshitz (LL) for the
momentum correlation function, we obtain a proton-proton momentum correlation
function for the specific three-body photon-disintegration channels of $^{12}$C
and $^{16}$O targets, which are assumed to have different initial geometric
structures, and extract their respective emission source sizes for the
proton-proton pair. The results demonstrate that constructing a proton-proton
momentum correlation is feasible in photo-nuclear reactions, and it is
sensitive to the initial nuclear structure. For future experimental studies
investigating the $\alpha$-clustering structures of light nuclei, the present
work can be used to shed light on the performance and correlation function
analysis of ($\gamma$,pp) or (e,$e'$pp) reactions.
