A new design method of broadband metallic diffraction gratings with single blaze surface

which has good applicability and implement in technology

is given. Basing on the principles of two types of grating anomalies

Rayleigh type and resonance type

the occurrence conditions of them are discussed. On the base of electromagnetic theory of gratings

the blaze character of diffraction efficiency both for TE and TM mode are numerically analyzed. It is found that the relationships between grating anomalies

the spectrum band of gratings and blazed wavelength. An idea of designing diffraction gratings is brought

which compensates Rayleigh anomaly or resonance anomaly with the first blazed wavelength of TM mode. The compensating effect of the first blazed wavelength of TM mode to Rayleigh anomaly is only the limitation case to resonance anomaly. The design examples of broadband metallic gratings with different groove density

which are applied in UV-visible

near infrared and infrared spectrometers

are given. The compensating effect method is better than the traditional design method of broadband metallic grating

whether in theory design or technology process

it makes the diffraction efficiencies of broadband metallic gratings to be over 40% in different spectrum band.