Bell believed the photophone's principles were his life's "greatest achievement", telling a reporter shortly before his death that the photophone was "the greatest invention [I have] ever made, greater than the telephone". The photophone was a precursor to the fiber-optic communication systems which achieved popular worldwide usage in the 1980s. Its master patent was issued in December 1880, many decades before the photophone's principles came into popular use.
ఫోటోఫోన్ ఏ ప్రసిద్ధ ఆవిష్కరణ కంటే మంచిదని బెల్ భావించాడు?
telephone