apparatus is applicable by way of example to treatment of blood vessels using endovascular techniques application_number US 71478507 A description as illustrated in fig3 the apparatus of a preferred embodiment of the invention includes an energy delivery device in the form of an optical fiber 10 that is introduced into the vessel 11 by means of a teflon_ introducer 12 the teflon introducer lacks a homeostasis valve and has a closed end 13 that extends beyond the tip 14 of the fiber 10 and that has an end 15 arranged to prevent contamination of the fiber tip 14 by blood 11 in the vessel the teflon introducer may optionally include a motorized fiber pull back 16 in addition a detector 17 may be included as described in more detail below end 15 of the introducer may be either open or closed if it is completely closed then the end may including cooling means within the introducer for cooling the fiber cooling means for use in a catheter are well known and the details of the cooling means do not form a part of the present invention alternatively the end 15 of the introducer may be open in which case saline or other irrigation fluid may be introduced at the opposite end to.