A new concept enhances the capability of photo-thermal absorption measurements with transversal probe beam guiding by overcoming drawbacks like sensitivity lack for materials with low photo-thermal response and/or round substrate geometries. The sandwich concept using the laser induced deflection (LID) technique is introduced and tested for the investigation of highly reflecting (HR) coatings. The idea behind the sandwich concept is based on the decoupling of the optical materials for the pump and probe beams. This is realized by either placing a HR coated rectangular substrate in between two optical (sandwich) plates or attaching a HR coated thin round substrate onto one optical plate. For both configurations, the sandwich concept results in a strong increase in sensitivity for the measurement of HR coatings deposited onto photo-thermally insensitive substrates. Experiments reveal that for a CaF2 substrate up to two orders of magnitude enhancement in the sensitivity can be achieved.