How to make my computer unlock after I scan my fingerprint?

So you probably have heard of "Touch ID" for iPhone 5S. If not, let me explain it to you. In order to unlock your iPhone, you need to scan your fingerprint on the home button.
I would like to do something like that for my computer. How can I do so? I know that the first step is to get a fingerprint scanner, I saw one for $50 on Amazon. But what's next? Is there any software for that?

There's a USB device that is a Fingerprint Reader. The software should come with it when purchased.

BUT, here's the downside. Easy to copy your fingerprint. You naturally leave them all over your computer. So just like Law Enforcement copies a fingerprint, so can someone trying to gain access to your computer. The same can be said about a Cell Phone.

Nothing beats a STRONG Password