laser safety

[ola27]

I have 2 Qs I could not solve them



If you had a laser that emits blue light at 480 nm wavelength and 100mW power, how wide must the beam be if it is to be safe when shone at a human eye for up to one minute?




For the grating you used (1.66µm groove spacing), is there a wavelength for which you cannot get any diffracted orders?



what do u think answers would be

Thanks

[Einstein Uae]

shall you show us what you have done so i can help you

at least tell me how u think about the 2 questions and what are the equations needed for those two questions

waiting for your response