A mobile device includes a see-through display unit, a back cover, a first optical unit and a processing unit. The first optical unit is arranged between the see-through display unit and the back cover, and is configured to capture a first optical result along a first optical path, which passing through an active region of the see-through display unit. The processing unit is coupled to the first optical unit and the see-through display unit. The processing unit is configured to determine a first portion on the see-through display unit according to the first optical path in response to the first optical unit is triggered to capture the first optical result, and control the first portion of the see-through display unit to be transparent while capturing the first optical detection result or adjusting the first optical detection result according to display contents within the first portion on the see-through display unit.