He pioneered the use of optical Doppler shift to measure the rotational rates of distant objects .
Belopolsky was known for his fine instrument making , and in 1900 he built a device for measuring the Doppler shift of spectra .
Belopolsky pioneered the use of optical Doppler shift to measure the rotational rates of distant objects .
Belopolsky was known for his fine instrument making , and in 1900 he built a device for measuring the Doppler shift of spectra .