Option 1 - Using Iris Scanner
Select Settings from the home screen.
Select Lock Screen and Security.
Select Iris Scanner.
Select Continue and then choose either your PIN code, unlock pattern or password as an additional secure screen lock (this just adds an additional level of security).
Once you’re done, hold your phone 25-30 cm from your eyes, keeping them inside the circles shown on the screen.
Select Turn On if you wish to use Iris Scanner to unlock your phone.