A new technique has been developed for amplification of the photothermal beam deflection angle for mirage detection. This technique, based on a very simple operating principle, uses a cylindrical reflection mirror. The use of a new amplifier provided a signal-to-noise ratio approximately 10 times that obtained without the amplifier for equipment of the same size. By using the new amplifier, a m...

For application in UV-material processing and UV-thin-film optics, the thermal contribution to damage and ablation phenomena will be investigated utilizing time resolved photothermal probe beam deflection (MIRAGE) technique. The potentiality of this method for the determination of both the sub-damage range and the Onset of damage, as well as the ablation threshold by using the thermal branch of...

In this chapter, a prototype small photothermal deflection apparatus was constructed on a laboratory bench. Not including excitation laser, data collection computer, and gas pumps, the apparatus fits on a bench space with a footprint of about 10 cm x 10 cm. This is a prototype apparatus that will be miniaturized in future assemblies. The apparatus was tested relative to the conventional laborat...

Abstract III-V nitride semiconductors have been characterized by photothermal deflection spectroscopy (PDS) which can provide the information of non-radiative recombination involving defect levels. After understanding challenges applying PDS to materials emitting light, advantages and features were described for evaluating defects level in band gap. The reciprocal slope spectrum near bandgap en...

We describe a direct method for the detection of optically excited ultrashort stress pulses in thin films using a time-resolved pump and probe scheme. Changes in the surface profile are monitored by the angular deflection of a probe beam. Application to the detection of interfacial layers is also demonstrated. The time-resolved detection of high frequency phonons excited by picosecond or femtos...

Hadamard transform spatial multiplexing techniques are applied to laser densitometry in order to prevent the photo-induced degradation of sensitive materials. Photochemical and thermal degradations can often occur in point focused scanning laser densitometry. In spatial multiplexing, the excitation source is defocused and efficiently distributed throughout the sample, reducing local power densi...

Efficient and targeted delivery of impermeable exogenous material such as small molecules, proteins, and plasmids into cells in culture as well as in vivo is of great importance for drug, vaccine and gene delivery for different therapeutic strategies. Though advent of optoporation by ultrafast laser microbeam has allowed spatial targeting in cells, the requirement of high peak power to create h...

A diffraction theory of continuous-wave photothermal deflection (PD) spectroscopy with fundamental and harmonic responses is presented. The displacement of the probe beam centroid is found to be a rigorous measurement of PD effect, which leads to a set of analytical solutions to the fundamental and the second-order harmonics. Harmonics are caused by the diffraction of the probe beam in the mira...