Optical configuration of a medicament reservoir of a drug delivery device

A drug delivery device comprising:

• a reservoir comprising a wall defining a proximal end and a distal end;
• a stopper comprising an optically reflecting element, the stopper being configured to expel a portion of a medicament stored within the reservoir by moving within the reservoir in a direction from the distal end to the proximal end, such that a stopper position is indicative of an amount of the medicament within the reservoir;
• a light emitting system being configured to provide a light signal towards the stopper from the proximal end;
• and
• a light detection system being configured to detect a reflected light signal provided by a reflection of at least a portion of the light signal on the optically reflecting element of the stopper, the reflected light signal travelling towards the proximal end and through a first portion of the wall of the reservoir and a light collector that comprises a geometry configured to direct the reflected light signal to a light detector that is configured to provide an electrical signal in response to detecting the reflected light signal.

A drug delivery system comprising:

• a drug delivery device comprising
• a reservoir comprising a wall defining a proximal end and a distal end;
• a stopper comprising an optically reflecting element, the stopper being configured to expel a portion of a medicament stored within the reservoir by moving within the reservoir in a direction from the distal end to the proximal end, such that a stopper position is indicative of an amount of the medicament within the reservoir;
• a light emitting system being configured to provide a light signal towards the stopper from the proximal end;
• and
• a light detection system being configured to detect a reflected light signal provided by a reflection of at least a portion of the light signal on the optically reflecting element of the stopper, the reflected light signal travelling towards the proximal end that travelled through a second portion of the wall of the reservoir and a light collector that comprises a second geometry configured to direct the reflected light signal to a light detector that is configured to provide an electrical signal in response to detecting the reflected light signal;
• and
• an external device comprising
• a receiver being configured to receive injection device data;
• and
• one or more processors being configured to process the injection device data and to generate result data.