Cooling device of a planar light source

A method of manufacturing a planar optical source, said planar optical source comprising:

• a plurality of linear optical sources stacked with each other, each of said linear optical sources comprising:
• a cooling device formed of a layered body of metal plate members stacked with each other, said layered body including a first coolant passage to which a cooling medium is supplied, a second coolant passage from which said cooling medium is discharged, and a third coolant passage interconnecting said first and second coolant passages;
• and a light emitting array provided on said cooling device, said light emitting array having a first electrode of a first polarity connected to said cooling device and a second electrode of a second opposite polarity;
• a conductor plate having an opening exposing said first and second coolant passages of said layered body;
• an interconnecting structure connecting said second electrode and said conductor plate electrically;
• and
• an elastic body fitted into said opening of said conductor plate, said elastic body having a thickness exceeding a thickness of said conductor plate and formed with first and second openings in correspondence to said first and second coolant passages;
• said plurality of linear optical sources being stacked such that a first coolant passage of a linear optical source is aligned with a first coolant passage of an adjacent linear optical source and such that a second coolant passage of a linear optical source is aligned with a second coolant passage of an adjacent linear optical source;
• a spacer being disposed between a first linear optical source and a second linear optical source provided right upon said first linear optical source, such that a bottom surface of said spacer is in surface engagement with said conductor plate on said first linear optical source and a top surface of said spacer similarly engages with a bottom surface of said cooling device of said second linear optical source, said spacer comprising a conductive spacer plate and an elastic spacer member provided on said conductive spacer plate, said conductive spacer plate having a third opening in alignment with said first coolant passages of said first and second linear optical sources and a fourth opening in alignment with said second coolant passages of said first and second linear optical sources, said conductive spacer plate carrying a depression in which said elastic spacer member is seated;
• said method comprising, in each of said plurality of linear optical sources, the step of:
• forming said conductor plate and said spacer conductor plate by a chemical etching process that uses a resist pattern.