Cryocooler with heat transfer blocks having fins

A cryocooler comprising:

• an expansion chamber;
• a cooling stage thermally coupled to the expansion chamber, the cooling stage comprising:
• a first heat transfer block provided with a surface exposed to the expansion chamber and a first heat exchange surface disposed outside the expansion chamber, and
• a second heat transfer block provided with a second heat exchange surface facing the first heat exchange surface;
• a refrigerant supply port installed in the cooling stage outside the expansion chamber;
• a refrigerant discharge port installed in the cooling stage outside the expansion chamber;
• and
• a refrigerant path fluidically separated from the expansion chamber, the refrigerant path being formed between the first heat transfer block and the second heat transfer block such that a refrigerant flows from the refrigerant supply port to the refrigerant discharge port along the first heat exchange surface and the second heat exchange surface,
• wherein the first heat exchange surface is provided with a first base surface and at least one first fin extending from the first base surface, the first fin being provided with a first fin tip end,
• wherein the second heat exchange surface is provided with a second base surface and at least one second fin extending from the second base surface along the first fin, the second fin being provided with a second fin tip end,
• wherein the first fin tip end is disposed closer to the second base surface than the second fin tip end and the second fin tip end is disposed closer to the first base surface than the first fin tip end,
• wherein the refrigerant path is provided with:
• a first transverse path formed between the first fin tip end and the second base surface such that the refrigerant crosses over the first fin,
• a second transverse path formed between the second fin tip end and the first base surface such that the refrigerant crosses over the second fin, and
• an inter-fin path formed between the first fin and the second fin such that the first transverse path communicates with the second transverse path,
• wherein the first transverse path is locally formed between the first fin tip end and the second base surface,
• wherein the second transverse path is locally formed between the second fin tip end and the first base surface, and
• wherein arrangement of the first transverse path and the second transverse path is determined such that a refrigerant stream in the inter-fin path is guided in a direction that forms an angle with a fin height direction.