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Since Multiphoton Lithography (MPL) is applied as an additive manufacturing technique for the fabrication of operational microsystems, the need to predict the mechanical response of the fabricated structures emerges. This work focuses on determining the Young's Modulus of structures fabricated via MPL. With this objective in mind, two series of experiments were designed and conducted: the first one for the determination of the factors whose impact is significant, and the second one for generating a dataset used in the training of a machine learning tool that will define the suitable set of fabrication parameters for the fabrication of a structure with desired Young's Modulus. 

Photothermal microscopy is a powerful method for investigating biological systems and solid state materials. Using a modulated pump to excite the sample, a continuous probe beam monitors the change in the refractive index of the sample due to the modulated heating. These experiments are typically performed at high frequencies to reduce the 1/f noise, achieving a higher signal to noise ratio. In this paper, we explore how the resolution and sensitivity of the photothermal experiments change when the modulation frequency is brought down below 100kHz. In the instance that the pump and probe are cofocused at the sample, the resolution is determined by the size of the pump beam. On the other hand, when a widefield pump is used, significant broadening occurs for frequencies under 20kHz. This broadening is attributed to thermal diffusion. However, the amount of broadening is less than that expected from the thermal diffusion length, which is about 1.7μm at 10kHz for nanoparticles in glycerol. We also explore the situation where the point spread functions of the pump and probe beams are smaller than the particle size as well as how the penetration depth depends on the properties of the pump and probe beams.