@Samuel_Bouchard based on past projects, I would say it depends on the application. Light curtains and safety mat can be a little less expensive than the area scanner. However the downside to safety mat and light curtains is that once you pass the barrier, you may still be in a dangerous zone but the curtains or mat won't detect you anymore. This can often easily be solved by using an area scanner. So this one of the reason why I like safety scanner better! The scanners also offer more flexible solution because of the setups you can do in these.
@Samuel_Bouchard
We have used pressure pads in the past and they worked very well, as the entire safe zone had mats placed in it anytime an operator was inside that zone the robot stopped working. Since the reach on the UR is not very long (relatively speaking) its not an issue. We have also looked at safety area scanners, more so for us since they are redeploy able and fit our business model better. We have also used light curtains, not to protect the operator from the robot directly but to prevent the robot from cycling a press while anything is inside the press that should not be there.
Our newest UR3 is a table top tapping station and it actually has a cage around it with a door, this just made sense in this application and only cost a couple hundred dollars so @Sebastien is right on in saying, it depends. Every application and situation is different. Our weirdest safety system is we have a robot installed in his own "office" and the door is kept shut between him and the humans and they have a window where they can watch him work. Its what the customer wanted.
Light curtain? Safety 3D scanner? Safety mat? What are the pros and cons of each?