Transmittance measurements for filters of optical density between one and ten

Abstract

We have developed a facility for measuring the transmittance of optical filters at a wavelength of 1064 nm, using a Nd:YAG laser, a power stabilizer, and linear photodiode detectors. A direct measurement method was used for filters with optical densities (OD's) less than or equal to 4, and a reference substitution technique was used for filters with OD's as great as 10. The apparatus and data-acquisition system are described. Measurement results for a set of filters are presented. The expanded uncertainties for the measured OD and deduced absorption coefficient are determined through a detailed analysis of all the uncertainty components.

Temperature and temporal dependence of neutral density transmittance standards

“…The implication is that changes in transmittance are due to changes in absorption in the bulk of the filters, not surface effects. This is in agreement with the results of Zhang et al [3] who showed that the temperature coefficient of transmittance of NG9 between 20 • C and 28 • C correlated with the thickness of the filter. Their results obtained at 1064 nm on NG9 are also shown in figure 3 along with similarly transformed results on NG4 between 20.5 • C and 25.5 • C from an NBS special publication [4], coefficients determined by HUT on a 1% transmitting filter between 20 • C and 30 • C [5] and measurements made at NPL on NG11, NG4 and NG9 between 25 • C and 35 • C [6].…”

“…Figure 3. Temperature dependence of absorption coefficient for four types of NG filter as measured for the W set of K6.2010 filters and as calculated from reported temperature coefficients of transmittance by several other authors[3][4][5][6] (error bars on the NPL data represent the standard uncertainty). Inset: absorption coefficient (linear absorption coefficient per centimetre pathlength per per cent mass fraction of oxide) for ions in silicate glasses[10].…”

Wide-angle near infrared polarizer with extremely high extinction ratio

“…It should be noted that the extremely high extinction ratio will be important for devices or systems that require ultrahigh polarization purity such as high power laser systems and high contrast modulators. If used in Faraday isolators, the proposed polarizer will help to suppress the back light completely, given that transmittance down to 10 −11 is still measurable [16]. The transmittance spectra are featured with two peaks labeled as P1 and P2.…”

Determination of tailored filter sets to create rayfiles including spatial and angular resolved spectral information

“…Therefore by not considering the effect as a functional relation we just neglect the change of those 0.25% difference as a function of the uncertainty terms. For the same reason we also neglect dispersion effects and thermal expansion [17]. Also note that the linear temperature dependence in Eq.…”