White-light spectral interferometric technique to measure the wavelength dependence of the spectral bqandpass of a fibre-optic spectrometer

Dispersive spectral-domain two-beam interference analysed by a fibre-optic spectrometer

“…We displaced mirror 2 manually by using the micropositioner with a constant step of 10 mm and chose the spectral region from 500 to 850 nm as that in which the spectral interference fringes should be fully observable. We revealed that due to the limited resolving power of the spectrometer S2000 [8] the OPDs between beams of the interferometer can be adjusted in the ranges approximately from -70 to -10 mm and from 10 to 70 mm. As an example, figure 2 shows by the solid line the recorded spectral interferogram corresponding to the adjusted OPD between beams of the interferometer of approximately 10 mm.…”

“…Assuming a case of a fibre-optic spectrometer with Á R ¼ 3 nm [8], the maximum range of the displacements of the interferometer mirror is ÁL max % 110 mm for the wavelength 1 and ÁL max % 330 mm for the wavelength 2 . When a dispersive interferometer is considered and when the spectral interference is analysed by a fibre-optic spectrometer, the channelled spectrum can be clearly resolved only in the vicinity of the equalization wavelength 0 , for which the relation Á g ð 0 Þ ¼ 0 is fulfilled and the spectral interference fringes have the highest visibility [14,15].…”

“…The wavelength of the spectrometer is calibrated so that a third-order polynomial relation between pixel number and wavelength is used. The spectrometer resolution is in our case given by the effective width of the light beam from a core of the read optical fibre: we used the read optical fibre of a 50 mm core diameter to which a Gaussian response function corresponds [7,8].…”

“…Among the functions and parameters characterizing spectrometers, response functions and bandpasses are the most important. Time-domain and spectral-domain interferometric techniques [2,3], including the applications of Fabry-Perot and Michelson interferometers or prism-and grating-based spectrometers, play key roles in measuring not only the temporal coherence functions and the spectra of light sources, but also the parameters and characteristics of the spectral instruments [4][5][6][7][8][9]. Thus, instrument functions [4], modulation transfer functions [5] and spectral slit widths of a grating [5] and a prism spectrometer [6] have been measured or determined for given spectrometer slit widths.…”

“…More recently, time-domain and spectral-domain low-coherence interferometry has been used to measure the spectral bandpasses of a fibre-optic spectrometer with different read optical fibres [7]. Most recently, a white-light spectral interferometric technique has been used to measure the wavelength dependence of the spectral bandpass of the spectrometer [8]. Moreover, the constant-bandwidth operation of the Czerny-Turner monochromator has been reviewed [9].…”