That appears to be for the GNAT series of German torpedoes and while they may, indeed, refer to it as a fuse, in the U S Navy they are referred to as Exploders or Exploder Mechanisms. It will make a difference if you try to search the web for them.
During the 1930’s the Navy began experimenting with a dual system (contact or influence) for detonating torpedoes and it is still in use today, though greatly improved. The early MK 6 Exploder was the cause of some of the problems encountered with the MK 14 and MK 15 torpedoes early in the war but once those bugs were ironed out, it became very effective.
The MK 6 was a hunker of a piece of gunmetal (as I recall) and a pain to work with but the detonators came seperate and were usually installed after the weapon was on board the sub or vessel. This meant removing the exploder and installing the detonator cups which were stored outside the Torpedo Room. Even after the detonator was installed it required water run time to charge the capacitor and remove a safety device from the detonator cup so they were fairly stable. I’m sure this was a design feature because torpedoes were known to come loose and knock around during depth charge counter-attacks.
Current exploders are about the size of a coffee can and come installed, ready to go. There is usually a safety device which requires removal before launch and the required in water run to arm the exploder.
The above applies to US torpedoes. I will try to get some photos but most of the post WWII Exploders are probably still classified material. The face of the MK 6 is very interesting. It fits into the bottom of the torpedo, not the front or tip.