Optical techniques are extremely well received in the field of Cultural Heritage conservation because they allow completely safe testing. This requirement is essential due to the uniqueness and fragility of artworks. A variety of optical investigation methods applied to paintings are, by now, an integral part of the repair process, both to study and evaluate the conservation state of the artwork, and to plan the restoration intervention and monitor its various phases. We present several techniques, developed at the Istituto Nazionale di Ottica CNR-INO in Florence, that have proven to be very useful in the analysis of paintings. They are not routinely applied yet, because research is still at its early stage in those fields. The prototypes developed are currently placed at the Opificio delle Pietre Dure in Florence, a key Institution for conservation and restoration, where INO's researchers work in an Optical Metrology Laboratory where the new instruments are calibrated and tested.