Lighting device, luminaire and lighting device assembly method

A lighting device comprising:

• a glass tube;
• a solid state lighting assembly in said glass tube, said assembly comprising:
• an electrically insulating optical film comprising at least one arcuate portion lining a part of the inner surface of the glass tube, wherein the glass tube further comprises a further part defining a light exit portion;
• and
• a plurality of solid state lighting elements on a carrier, said carrier contacting said optical film;
• a thermally conductive member in between at least a part of the solid state lighting assembly and the glass tube for thermally coupling the solid state lighting elements to the glass tube;
• and
• a transparent or translucent electrically insulating cover contacting the electrically insulating optical film and covering the solid state lighting elements, wherein the transparent or translucent electrically insulating cover forms part of an electrically insulating plastic sleeve comprising:
• a central compartment;
• and
• at least one arcuate further portion extending from said central compartment, each arcuate further portion being mounted on and matching the at least one arcuate portion of the electrically insulating optical film.