Calorimetric study of optical absorption of Suprasil W-1 fused quart at visible, near-IR, and near-UV wavelengths

Measurements of Radiation Pressure Owing to the Grating Momentum

The radiation pressure force on a nearly single-order diffraction grating was measured for a transmission grating near the Littrow angles at wavelengths of 808 and 447 nm. The component of force parallel to the grating agreed well with our prediction, being proportional to the product of the grating order and the ratio of the wavelength and grating period. The normal component of force varied with the incident angle, vanishing near the Littrow angle as expected. The measurements verify a correspondence between the Fourier grating momentum and the mechanical momentum. This Letter provides opportunities for in-space fly-by-light sailcraft as well as terrestrial applications.

Measuring the absolute absorptance of optical laser components

The precise determination of the absolute absorptance of a laser component is of high scientific and commercial importance. Our intention is to demonstrate that laser calorimetry can be a reliable and sensitive characterization tool for this purpose. Furthermore, the limitations of laser calorimetry are discussed and suggestions for possible revisions of the ISO 11551 (International Organization for Standardization, Geneva, Switzerland) standard are made. Finally, laser calorimetry is compared with photothermal deflection methods with respect to their practicability in different fields of laser optic characterization.

Monte Carlo modeling of the performance of a reflective tube absorption meter

A Monte Carlo model of the behavior of photons in a reflective tube absorption meter has been developed and used to investigate how well such a meter can measure the absorption coefficient in waters of different optical types. The apparent, i.e., measured, absorption coefficient (alpha(m)) is always greater than the true absorption coefficient (alpha). The ratio alpha(m)/alpha increases linearly with the ratio of scattering to absorption (b/alpha) at a rate that depends on the scattering phase function of the water. The excess attenuation is mainly due to the failure of forward-scattered photons to undergo reflection at the cylinder wall. To achieve the highest accuracy possible with the meter, one must maximize the reflectivity and detector acceptance angle. Performance is also improved by increasing the cylinder diameter.