Prototyping a Photodiode-based X-ray Sensor

Abstract

The purpose of this thesis is to design a prototype for an X-ray sensor using a photodiode. This sensor has two applications: Measure the density of nonwoven textile for quality control in a production line; Measure the output intensity of an X-ray generator used in an existing density sensor to account for the instability of the generator. The thesis begins with a theoretical study of the behavior of photodiodes and X-rays. A first prototype for the sensor was built starting from zero with every design choices described in detail. An in depth experimental noise analysis was conducted. Then a data acquisition system was designed using an STM32 microcontroller. Experimental measures were conducted to evaluate the prototypes performances for both application. A second iteration of the prototype was built using the base of the first one. Again, a noise analysis was performed. The same experimental measures were taken to evaluate the performance of this second iteration. Both prototypes results areanalyzed and compared. In the end the thesis provides an overview of the possible benefits and issues of these sensors for their required applications. The conclusion also provides some areas of improvements and ideas for further work.