The Perkin Elmer Lambda 900 spectrophotometer has been used to perform measurements of spectral reflectance in the NIR/Vis/UV range from 250 nm to 2200 nm at variable angle of the incident light from 8° to 78°. To perform this type of measurements, the Lambda 900 has been equipped with two integrating spheres, one for accommodating the sample and orienting it with respect to the incident sample beam, the other for measuring the intensity of radiation reflected by the sample. Measurements of angle-resolved spectral reflectance were then performed on a set of standards of diffuse reflectance from Labsphere.
A new method is presented for measurements of angle-resolved reflectance of a plane surface. The main innovation introduced by the method consists in allowing to carry out reflectance measurements from 0° to 90° of incidence angle. This was obtained by changing the technique of sample illumination: instead of illuminating a portion of the test surface, the entire test surface is illuminated by a collimated and uniform beam at any angle of incidence. To be applied, the method requires, besides measurement on the unknown sample, also measurements on two different standards of diffuse reflectance. The method is particularly suitable for the optical characterization of photovoltaic devices, generally exposed to the inclined light of the direct component of solar radiation.
Doppler tracking experiments using the earth and a distant spacecraft as separated test masses have been used for gravitational wave (GW) searches in the low-frequency band(~0.0001-0.1 Hz). The precision microwave tracking link continuously measures the relative dimensionless velocity, Δv/c, between the earth and the spacecraft. A GW incident of the systems produces a characteristic signature in the data, different from the signatures of the principal noises. For 40 days centered about its solar opposition in December 2001, the Cassini spacecraft was tracked in a search for low-frequncy GWs. Here we describe the GW experiment, including transfer functions of the signals and noises to the Doppler observable, and present noise statistics and compare them with the pre-experiment noise budget.