If your laptop has a built-in fingerprint reader, here is how to enable it for logins under gnome3. In this example, I’m using a Lenovo T60 laptop.
Start the Authentication application.
On the advanced options tab, enable the fingerprint reader.
Next open a terminal window.
Run fprintd-enroll with your username. To record your fingerprint scan, it will ask you to swipe your index finger three times successfully.
That is all. You can test by logging out and logging in again. On the gdm login screen, select your username and select the icon for the fingerprint. Then scan your right index finger and it should log you in.