Apparatus and method for analyte measurement with improved detection of the deflection of a detection light beam

An apparatus for analyzing a material comprising at least one analyte, said apparatus comprising

• a measurement body having a contact surface suitable to be brought in thermal contact or pressure-transmitting contact with said material, said thermal or pressure-transmitting contact permitting heat or pressure waves generated by absorption of excitation radiation in the material to be transferred to said measurement body,
• an excitation radiation source configured for irradiating excitation radiation into the material to be absorbed therein, and
• a detection light source for generating a detection light beam travelling through at least a portion of said measurement body or a component included in said measurement body,
• wherein said detection light beam is directed to be totally or partially reflected at said contact surface, wherein said detection light beam is deflected upon heat or pressure waves generated by absorption of excitation radiation in the material being transferred to said measurement body, and
• a detector for detecting a degree of deflection of the detection light beam after its reflection at said contact surface,
• wherein said contact surface of the measurement body is curved in at least one principal direction in an area where the detection light beam is reflected, wherein the detection light beam prior to and after reflection at said contact surface defines a detection light plane, and wherein said principal direction lies within said detection light plane or forms an angle with the detection light plane that is less than 30°.