Apparatus for determining information associated with reflection characteristics of a surface

An apparatus comprising:

• a sensor configured to generate sensor output dependent on an intensity of light incident on the sensor, the sensor having a field of view directed at an external surface;
• an illumination source configured to emit light onto the external surface;
• a window configured to allow light to pass from the illumination source to the external surface and to allow light to pass to the sensor from the external surface;
• a shield coupled to or integral with the window, the shield being substantially opaque to substantially all wavelengths of light detectable by the sensor and defining an aperture which limits the field of view of the sensor;
• and
• a processor coupled to the sensor, the processor configured to use the sensor output to determine information associated with reflection characteristics of the external surface.

A device assembly comprising:

• an injection device comprising an external surface;
• and
• an apparatus configured to be attached to the injection device, the apparatus comprising:
• a sensor configured to generate sensor output dependent on an intensity of light incident on the sensor, the sensor having a field of view directed at the external surface of the injection device;
• an illumination source configured to emit light onto the external surface;
• a window configured to allow light to pass from the illumination source to the external surface and to allow light to pass to the sensor from the external surface;
• a shield coupled to or integral with the window, the shield being substantially opaque to substantially all wavelengths of light detectable by the sensor and defining an aperture which limits the field of view of the sensor;
• and
• a processor coupled to the sensor, the processor configured to use the sensor output to determine information associated with reflection characteristics of the external surface.