After sourcing my artwork I edited in Xtool Creative Space which I find very adequate for allowing greyscale or black and white images to be presented with fine detail, highlights, shadows mid shades and contrast.
I use a standard generic aluminium business card to lay my image down using the following settings.

Manual Settings
Invert Image
IR Laser type
Dot Duration 365
Power% 65
Dots Per Inch (DPI) 365
Bitmap Mode - Jarvis
Engraving Mode - Bi-directional.

I use these settings and test to see if the image turns out detailed crisp with good greyscale contrasts.
You can tweak any of the settings but need to be careful that the end result isn't distorted.