Quantum Dot Encoder via Near-Field Direct Writing

Grating lithography has been successfully employed to fabricate the gratings of optical encoders, which is increasingly unsuitable for the fast and mass production of optical encoders. Due to the advantages of high efficiency, low cost, and simple process requirements, we make the first attempt to introduce additive manufacturing with perovskite quantum dots (QDs) to fabricate a novel linear encoder, which is named quantum dot encoder. First, to better print coding patterns, a new printing ink is created by combining perovskite quantum dots with polycaprolactone (PCL). Then, an innovative coding pattern is printed on the glass substrate by the near-field direct writing with the new ink, which can achieve an actively produced optical signal directly instead of the passively produced optical signal in traditional optical encoders. Finally, a new measurement system for quantum dot encoder is established and an image processing method is elaborately designed to implement the displacement measurement. Simulations indicate that the quantum dot encoder can avoid the thermal deformation caused by the overheated light source, which is beneficial for the decoding precision. Measurement results indicate that the designed quantum dot encoder with a low-speed motion platform and a low-frame charge coupled device (CCD) can achieve a fair measurement precision at a reasonable displacement velocity, which validates our innovative approach for the fabrication of the linear encoder by means of additive manufacturing with perovskite quantum dots.