Patent ID: 7814777

Claim:
A photo-acoustic device ( 100 ) for detecting the presence of a searched component in a sample ( 116 ), the device comprising: a sample cell cavity ( 102 ) containing the sample; a first light source ( 130 ) outside the sample cell cavity ( 102 ) emitting a first modulated light beam ( 114 ) at a wavelength in an absorbing range of the searched component; a cavity wall ( 106 ) for guiding the first light beam into the cavity; an acoustic pickup unit ( 110 ) for capturing first acoustic waves generated in part by the searched component absorbing the first light beam; characterized in that, the device is further equipped with a background acoustic wave cancellation system ( 120 , 122 , 140 , 144 ) that generates a second set of acoustic waves in anti-phase with background acoustic waves caused by the absorption of the first light beam by the cavity wall and the second set of acoustic waves cancel out the background acoustic waves at the acoustic pickup unit.