List of Contributors. Preface. E.D. Palik, Introductory Remarks. T.J. Parker, K.A. Maslin, and G. Mirjalli, Determination of the Far Infrared Optical Constants of Solids by Dispersive Fourier Transform Spectroscopy.A. Mandelis, Photothermal/Photoacoustic Spectroscopic Measurements of Optical Absorption Coefficients in Semiconductors. M.E. Briggs, Photothermal Deflection Measurements of the Extinction Coefficient k. H. Boukari and N. Lagakos,Determination of Optical Constants by Brillouin Scattering. M. Auslender and S. Hava, Doped n-Type Silicon (n-Si). E.D. Palik, Optical Parameters for the Materials in HOC I, II, III. References. Critiques-Metals: Introduction to the Data for Several Metals. L. Ward, Optical Constants of Eight Rare Earth Elements. T. Inagaki and E.T. Arakawa, Cesium (Cs). C.G. Rinning and A. Roos, Zirconium Nitride (ZrN). C.G. Ribbing and A. Roos, Hafnium Nitride (HfN). Critiques--Semiconductors: Aluminum Nitride (AiN). E.D. Palik, Bismuth Silicon Oxide (Bi12siO20). E.D. Palik, Bismuth Germanium Oxide (Bi12GeO20). G.L. Doll, Boron Nitride (Bn). J.C. Riff, Cadmium Germanium Arsenide (CuGaS2). J.C. Riff, Copper Gallium Sulfide (CuGaS2). D.F. Edwards, Gallium Selenide (GaSe). D.F. Edwards, Gallium Telluride (GaTe). E.D Palik, Iron Pyrite (FeS2). J. Geist, Silicon (Si) Revisited.D.F. Edwards, Silicon (Si) Revisited. J. Humlicek, Silicon-Germanium Alloys (SixGe1-x). M. Tazawa and A, Handi, Silver Chloride (AgCl); Silver Bromide (AgBr); Silver Iodide (AgI). L. Artus, Silver Gallium Sulfide (AgGaS2). Silver Gallium Selenide (AgGaSe2). J. Misiewicz and K. Jezierski, Zinc Arsenide (Zn3As2). Zinc Phosphide (Zn3P2). J.C. Rife, Zinc Germanium Phosphide (ZnGeP2). Critiques--Insulators: M.E. Thomas and W.J. Thopf, Aluminum Oxide (Al2O3). Revisited. W.J. Tropf, Calcium Carbonate (CaCO3). W.J. Moore, Cesium Bromide (CsBr). J.E. Eldridge, Cesium Chloride (CsCl). J.E. Eldridge, Cesium Fluoride (CsF). D.F. Edwards,Gallium Oxide (Ca2O3). M.A.F. Destro and A. Damiao, Lead Fluoride (PbF2). F. Gervais and V. Fonseca, Lithium Tantalate (LiTaO3). M.E. Thomas, Potassium Iodide (KI). I. Biaggio, Potassium Niobate (KNbO3). I. Ohlidal and D. Franta, Rubidium Iodide (RbI). E.D. Palik and R. Khanna, Sodium Nitrate (NaNO3). M.E. Thomas, Stronium Fluoride (SrF2). K.A. Fuller, H.D. Downing, and M.R. Querry, Orthorhomic Sulfur (-S). W.J. Tropf, Cubic Thallium (I) Halides. W.J. Tropf, Yttrium Aluminum Garnet (Y3Al5O12). E.D. Palik and R. Khanna, Zircon (ZrSiO4).