title: Improvements for determining the modulation transfer function of charge-coupled devices by the speckle method.
abstract: We present and evaluate two corrections applicable in determining the modulation transfer function (MTF) of a charge-coupled device (CCD) by the speckle method that minimize its uncertainty: one for the low frequency region and another for the high frequency region. The correction at the low-spatial-frequency region enables attenuation of the high power-spectral-density values that arise from the field and CCD response non-uniformities. In the high-spatial-frequency region the results show that the distance between the CCD and the aperture is critical and significantly influences the MTF; a variation of 1 mm in the distance can cause a root-mean-square error in the MTF higher than 10%. We propose a simple correction that minimizes the experimental error committed in positioning the CCD and that diminishes the error to 0.43%.
authors.forename: A M
authors.initials: AM
authors.lastname: Pozo
authors.forename: A
authors.initials: A
authors.lastname: Ferrero
authors.forename: M
authors.initials: M
authors.lastname: Rubiño
authors.forename: J
authors.initials: J
authors.lastname: Campos
authors.forename: A
authors.initials: A
authors.lastname: Pons