Do lasers weapons pass through any obstacles?

This?

Lasers are high intensity light so technically speaking they cannot penetrate anything opaque. Instead, the energy in the laser is converted into heat which melts or vapourises whatever it contacts.

A bullet is a single piece of metal that transfers its kinetic energy to the target.
A laser is a continuous stream of particles that do the same.
In that way, you could compare the laser more to a machine gun that continuously and rapidly fires countless bullets onto the same spot on the target. Each bullet will do incremental damage, until they have ‘burrowed’ through the target, and then the stream of bullets will fly through the burrowed hole unimpeded.

A laser will not go through a mirror.

Most mirrors won’t reflect 100% of the light. The remainder will get absorbed: https://physics.stackexchange.com/questions/170972/how-reflective-are-typical-mirrors-in-the-visible-part-of-the-spectrum
So given a big enough laser, the mirror will get pretty hot and get damaged. Then reflectivity will go down and the heating situation will get worse.

It takes a lot of power and technology to make a laser strong enough to penetrate much. The

Dune or Warhammer 40K super-penetrating lasers are powered by some potent handwavium . . .

@RocketGuy And the glass that remains after the reflective treatment has been destroyed will not be affected. Meanwhile, the reflected laser will destroy it’s source, if reflected back that way.

@kritiper – only if the mirror is perfectly oriented perpendicular to the beam.