Your requirements are not very high. Almost any ADC could handle this task.
However, you are asking about a so-called safety interlock. You want to make a circuit that stops the machine if the machine becomes unsafe (specifically - if the laser is stronger than it should be). If the laser is too strong and the safety interlock doesn't work, someone could go blind. Therefore, you want to be really sure the safety interlock will work.
This requires a level of assurance that is not appropriate to a random Internet Q&A site. Sure, we can offer suggestions, like making the interlock out of hardware so it still works even if the software crashes, but they are just suggestions. If your device fails and makes someone blind, your company - or you - could be sued for millions of dollars.
If you've never heard of Therac-25 then click that and read about it. Therac-25 was a hospital machine designed to kill cancer by focusing radiation at it. And it was controlled by a computer, and the program had a bug - a race condition - if the operator entered commands too quickly, the software could get confused and the machine could send way too much radiation. This killed four people. You do not want to be the person who designed the machine that killed four people.
The previous version of the machine (the Therac-20) had hardware interlocks, so if the operator did this, it blew a fuse (on purpose). This is a good thing. Blowing a fuse is better than killing someone. In the Therac-25, they saved money by taking out the hardware interlock and relying on the software interlock. But the software was buggy. And people died.
And that is why you need to make sure someone who is properly qualified looks over your design and makes sure it is good enough. And why safety-critical software needs to be taken seriously. If you can't prove the software never crashes, then better not to make the software get involved at all. Your laser probably won't kill anyone, but it could make them blind, and that's nearly as bad.