SchoolDigger data sources: National Center for Education Statistics, U.S. Department of Education, the U.S. Census Bureau and the Minnesota Department of Education. IMPORTANT DISCLAIMERS: Not all boundaries are included. We make every effort to ensure that school and district boundary data are up-to-date.
The spectral sensitivity is typically expressed as a QE Curve, in which the probability to detect a photon of a particular wavelength is expressed as a percentage.So for example if one in every 10 photons is detected this is expressed as a QE of 10%. The curve for a typical CCD is shown in the diagram on the below:
A spectrophotometer measures the intensity of a light beam before and after it passes through a sample and compares these two intensities. The Spec 20 reports two types of measurements: percent transmittance and absorbance.Percent transmittance is the ratio of the intensity of the light passing through the sample to the intensity of the light shining on the sample multiplied by 100%.Absorbance is the log of the transmittance. The Spec 20 can measure absorbance and transmittance over a range of wavelenghts.You must select a wavlength and calibrate the instrument at that wavelength before making any measurements.bsorbance is the log of the transmittance. The Spec 20 can measure absorbance and transmittance over a range of wavelenghts. You must select a wavlength and calibrate the instrument at that wavelength before making any measurements.