of the lens barrel 10 so that the clip 50 will be in a compressed state when the clip 50 is located in the groove 104 of the lens barrel 10 and will fix the lens module 20 the spacer 30 and the filter 40 in the lens barrel 10 in alternative embodiments the clip 50 can be replaced by another fixation element which can fix the lens module 20 the spacer 30 and the filter 40 in the lens barrel 10 in assembly of the optical module 100 the lens module 20 the spacer 30 and the filter 40 are received in the cavity 101 of the lens barrel 10 in that order and the lens module 20 is adjacent to the partially closed end of the lens barrel 10 then the clip 50 aligns with the open end of the lens barrel 10 and an operator exerts a force on the clip 50 such that the clip 50 is deformed and located in the groove 104 at this time the lens module 20 the spacer 30 the filter 40 and the clip 50 are all received in the cavity 101 of the lens barrel 10 the spacer 30 is located between the lens module 20 and.