= Solution
The printed aerial image has approximately $I_{\max}=2.0$ and $I_{\min}=0.5\ \mathrm{mW\,cm^{-2}}$. Thus its modulation, and its modulation transfer for a fully modulated object, is
$$
\boxed{M=\frac{I_{\max}-I_{\min}}{I_{\max}+I_{\min}}
=\frac{2.0-0.5}{2.0+0.5}=0.60.}
$$
\b[The image does not meet the full-thickness printing criterion], because $0.60<0.667$. Equivalently, clearing the bright regions requires $t\geq100/2=50$ s, while preserving the full thickness in the dark regions requires $t\leq20/0.5=40$ s. There is no common exposure time.
Partial thickness modulation may remain visible, but that is different from a clean grating with fully cleared spaces and retained full-thickness lines. Small ripple peaks in the source drawing do not change this conclusion.
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