In one aspect, the invention provides a sample assembly to be used in a fluorescent measurement device. The sample assembly comprises a sample carrier, a sample holder that comprises at least one receptacle and a movable platform. The sample carrier is shaped in such a way that it can be secured into the receptacle by a suitable locking means. The sample holder is held in place on the movable platform through any suitable means, such as for example, a magnetic means. The movable platform is capable of moving in a linear trajectory, an arcuate trajectory and combinations thereof. The movement of the movable platform and hence, the entire sample assembly is effected by at least one stepper motor.