  The measurement of the spectral diffraction efficiencies of a diffraction
grating is essential for improving the manufacturing technique and for
assessing the grating's function in practical applications. The drawback of the
currently popular measurement technique is its slow speed due to the hundreds
of repetitions of two kinds of time-consuming mechanical movements during the
measuring process (i.e., the rotation of the mechanical arm to capture the
light beam, and the mechanical variation of the output wavelength of the
grating monochromator). This limitation greatly restricts the usage of this
technique in dynamic measurement. In this manuscript, we present a motionless
and fast measurement technique for obtaining the spectral diffraction
efficiencies of a plane grating, effectively eliminating the aforementioned two
kinds of mechanical movement. Herein, the proposed solution for removing the
first kind of mechanical movement is tested, and the experimental result shows
that the proposed method can be successfully used to measure the plane
transmission grating's spectral diffraction efficiencies in the wavelength
range of 550-750 nm. The method for eliminating the second kind of mechanical
movement is not verified in this manuscript; however, we think that it is very
straightforward and commercially available. We estimate that the spectral
measurement can be achieved on a millisecond timescale by combining the two
solutions. Our motionless and fast measuring technique will find broad
applications in dynamic measurement environments and mass industrial testing.
