Low consumption light source and sample cell composite device

The utility model discloses a low consumption light source and sample cell composite device comprising a light source of polychromatic light which comprises more than one kind of light in different ranges of wavelengths with continuous wavelengths in a finite spectral region, a light guide fiber feeding light beam and a sample cell of double luminous ranges. The low consumption light source and sample cell composite device can adjust the luminous ranges with few procreant heat and can shorten the luminous ranges of the sample cell, makes the luminous ranges of the sample cell correspond to one half of the luminous ranges of traditional sample cell, can avoid the operation of decanting samples by handwork, is convenient for the miniaturization and portability of instruments, and can be used for portable light spectrum analytic instruments with continuous wavelengths of alternating-current/direct-current.