  Circular dichroism in the angular distribution (CDAD) of photoelectrons from
SrTiO3:Nb and CuxBi2Se3 is investigated by 7-eV laser ARPES. In addition to the
well-known node that occurs in CDAD when the incidence plane matches the mirror
plane of the crystal, we show that another type of node occurs when the mirror
plane of the crystal is vertical to the incidence plane and the electronic
state is two dimensional. The flower-shaped CDAD's occurring around the Fermi
level of SrTiO3:Nb and around the Dirac point of CuxBi2Se3 are explained on
equal footings. We point out that the penetration depth of the topological
states of CuxBi2Se3 depends on momentum.
