Laser power meter based on the photomechanical effect

Laser power measurements use devices that transduce light energy into an electrical signal. Typical mechanisms used to measure laser power include the pyroelectric effect, photovoltaic effect, and thermoelectric effect. A method of measuring laser power using the photomechanical effect is presented in this poster. A diffraction grating was first imprinted on an poly(dimethyl siloxane) (PDMS) elastomer doped with the diazo chromophore, oil red O. The dispersive dye strongly absorbs blue and green light while transmitting red light. The first-order diffracted beam was measured with a 650nm laser and a 532nm pump laser was absorbed by the dye-doped PDMS film. The grating period increased when the green CW laser light was absorbed. The diffracted beam's angle was measured with a 5000-pixel linear CCD array. Two coupled rate equations were used to fit the angle as a function of time for many pump powers, which was used to calibrate the photomechanical laser power sensor.