Large Laser sensor that can detect a laser beam up to 30 or 40 meters

Hi guys i hope you can help me with this project.
Is it possible to have a Large laser sensor like 50cmx50cm that when it by a laser beam it triggers an alarm?
How powerful must the laser be? does it have to be an infra red laser?
What kind of laser sensors exist?

thanks

Most sensors have a very small area. Those that do not are the LDR type, but those are slow to react. What I have done in the past is to use two or three diffusers so the actual area of the sensor is less important.

Thank you for your reply. Can you explain to me more about the LDR sensor and those diffusers?
The diffusers can expand the area of one LDR and make it faster to react? Can you show me a link to those diffusers please just to have an ideia

and make it faster to react?

No.

The diffusers can expand the area of one LDR

No but it expands or spreads out the light from the laser from a spot into a larger area and therefore can match the light collecting area of an LDR.

Can you show me a link to those diffusers please just to have an ideia

It is not "those" diffusers, it is just any translucent material, maybe two separated by half an inch.

warning, never look into the laser with remain good eye.

A possibility: laser-lyte