Abstract
Optical Tweezers allow microscopic or sub-microscopic particles to be trapped in the beam waist of a focused laser and, via an optical control system, to move and measure the position of the particles with a nanometric resolution. But this optical setup can also be used as a local probe microscopy technique to produce a topographic map of a surface of a few microns. Photonic force microscopy (PhFM) is a near-field imaging technique based on the measurement, at nanometric resolution, of the position of an optically trapped particle while scanning the topography of a surface. Compared to conventional atomic force microscopes (AFMs), this technique has the advantage of applying a much lower force to the sample, opening up the possibility of imaging very soft materials such as cell membranes, without the deformation that often accompanies AFM imaging of these materials. In addition, the absence of a cantilever allows scanning in topologically restricted areas. However, the lateral resolution in PhFM remains limited by the geometry of the trapped object, which is often chosen spherical. In this thesis, I present a simple, economical and reliable nanofabrication process for the batch production of quartz microcylinders with a tip on one end. Due to the elongated particle geometry and birefringence of the Quartz, the linear polarized optical trap constrains all degrees of freedom of the cylinder, allowing stable trapping and nm resolution in detecting the particle position in all three directions. The size of the tip allows a lateral resolution of 30 nm, while applying a force as low as 1 pN to the sample. In addition to nanofabrication processes, this work focused on developing the PhFM imaging technique, the calibration of the probe's displacements to demonstrate its effectiveness in analyzing rigid surfaces but also biological objects such as microtubules or cell surfaces. As such, we were able to produce an image of a red blood cell membrane that shows the underlying structure of the cytoskeleton.