Defogging of protective sleeve for intraoral scanner

An intraoral scanning device, comprising:

• a housing having a longitudinal axis and comprising:
• a head configured for insertion into an oral cavity of a patient, the head comprising an aperture for transmission of optical signals;
• a transparent element positioned within the aperture, wherein the transparent element is non-orthogonal to the longitudinal axis;
• and
• a defogging unit comprising a heater;
• and
• a protective sleeve configured to cover at least a part of the head when the protective sleeve is coupled to the housing, the protective sleeve comprising:
• an additional aperture that aligns with the aperture;
• and
• an additional transparent element in the additional aperture;
• wherein the housing and the protective sleeve are configured such that a gap separates the additional transparent element from the transparent element when the protective sleeve is coupled to the housing;
• wherein the heater is configured to generate heat in response to application of electrical power to the heater;
• and
• wherein the housing and the protective sleeve are configured such that the heat generated by the heater is transferred from the heater to the additional transparent element despite the gap that separates the additional transparent element from the transparent element.