The NIST ytterbium-doped fiber laser used can provide up to 530 watts of laser output at a wavelength of 1.07 microns. At full power, they were able to deliver as much as 3.5 uN (0.35 mg) of force to the mirror. The experiments showed the expected linear relation between measured force and laser output.
It's just the way coffee is. Coffee is acidic. That's what probably upsets your stomach, especially if you're not eating or drinking other fluids throughout the day. People say that using coffee grounds are excellent for growing plants. BUT, they are only good for growing plants that are acidic soil loving plants.
Opt for decaffeinated green tea. Caffeine, when consumed in large doses, causes stomach irritation and nausea. It also makes your stomach lining secrete more acid. The caffeine found in green tea can worsen the symptoms of esophageal reflux, and cause stomach upset. You may want to consider high quality Japanese green tea such as gyokuro.