An ultrasonic transducer, comprising: a piezoelectric-vibrator assembly , having a first side and a second side opposite to the first side , and comprising one or more piezoelectric vibrators ; an acoustic matching layer , arranged on the first side of the piezoelectric-vibrator assembly ; a heat sink , arranged on the second side of the piezoelectric-vibrator assembly and comprising: a body , substantially in shape of a column and having a central axis; a head portion , disposed at one end of the body and facing towards the piezoelectric-vibrator assembly ; a tail portion , disposed at another end of the body opposite to the head portion and facing away from the piezoelectric-vibrator assembly , wherein the central axis extends in a direction from the head portion to the tail portion, the tail portion comprises a first surface disposed at one side of the tail portion facing away from the head portion , the first surface is an oblique surface or a tapered surface, and an angle between the first surface and the central axis is an acute angle; and an acoustic-absorption layer ; wherein the ultrasonic transducer is characterized in that the acoustic-absorption layer is completely covering an outer face of the heat sink and is configured to absorb ultrasonic waves refracted out of the heat sink . a piezoelectric-vibrator assembly , having a first side and a second side opposite to the first side , and comprising one or more piezoelectric vibrators ; an acoustic matching layer , arranged on the first side of the piezoelectric-vibrator assembly ; a heat sink , arranged on the second side of the piezoelectric-vibrator assembly and comprising: a body , substantially in shape of a column and having a central axis; a head portion , disposed at one end of the body and facing towards the piezoelectric-vibrator assembly ; a tail portion , disposed at another end of the body opposite to the head portion and facing away from the piezoelectric-vibrator assembly , wherein the central axis extends in a direction from the head portion to the tail portion, the tail portion comprises a first surface disposed at one side of the tail portion facing away from the head portion , the first surface is an oblique surface or a tapered surface, and an angle between the first surface and the central axis is an acute angle; and an acoustic-absorption layer ; wherein the ultrasonic transducer is characterized in that the acoustic-absorption layer is completely covering an outer face of the heat sink and is configured to absorb ultrasonic waves refracted out of the heat sink . a body , substantially in shape of a column and having a central axis; a head portion , disposed at one end of the body and facing towards the piezoelectric-vibrator assembly ; a tail portion , disposed at another end of the body opposite to the head portion and facing away from the piezoelectric-vibrator assembly , wherein the central axis extends in a direction from the head portion to the tail portion, the tail portion comprises a first surface disposed at one side of the tail portion facing away from the head portion , the first surface is an oblique surface or a tapered surface, and an angle between the first surface and the central axis is an acute angle; and an acoustic-absorption layer ; wherein the ultrasonic transducer is characterized in that the acoustic-absorption layer is completely covering an outer face of the heat sink and is configured to absorb ultrasonic waves refracted out of the heat sink . <EOS>