  METATOYs can change the direction of light in ways that appear to, but do not
actually, contravene the laws of wave optics. This direction change applies
only to part of the transmitted light beam; the remainder gets re-directed
differently. For a specific example, namely confocal pairs of rectangular
lenslet arrays with no dead area between lenslets, we calculate here the
fractions of power of a uniform-intensity light beam incident from a specific
(but arbitrary) direction that get re-directed in different ways, and we derive
an equation describing this redirection. This will facilitate assessment of the
suitability of METATOYs for applications such as solar concentration. Finally,
we discuss similarities between the multiple refraction of light at the lenslet
arrays and multiple refraction and reflection of cold atoms at a barrier in the
presence of the light fields.
