I agree that this device wouldn't work for that assay, but the opacity of the pills isn't a factor: the optical bench is too small and the illumination will be too low to do anything worthwhile.
So, I'm wrong to casually dismiss opacity of the target. That stems from a bias due to a background in instrumentation (meaning, I start my thinking there). I think I'm still right though to think that instrumentation is a bigger problem than sample prep for this device, which I didn't do a good job in stating earlier.