They work by refraction, or the bending of light.
ð eɪ WORD_BOUNDARY w ɜː k WORD_BOUNDARY b aɪ WORD_BOUNDARY ɹ ɪ f ɹ æ k ʃ ə n WORD_BOUNDARY ɔ ɹ WORD_BOUNDARY ð ə WORD_BOUNDARY b ɛ n d ɪ ŋ WORD_BOUNDARY ʌ v WORD_BOUNDARY l aɪ t WORD_BOUNDARY