The chemical structure of a sample can be characterized by its absorbance. The SpectraPro HRS provides accurate and reliable spectroscopy, ensuring consistently high spectral resolution. With an astigmatism-corrected design, the SpectraPro allows for repeatable quantitative chemical analysis.
Therefore, the SpectraPro can provide accurate and reliable spectra for all absorbance applications. Simple design and set-up allow for quick assembly of each experiment, with multiple accessories allowing for ultimate flexibility — ideal for switching between absorbance, reflectance and transmission spectroscopy with the same sample. With modular design, the portable IsoPlane 81 is able to cover multiple spectral ranges dependent on the area of interest.
This allows for multiple absorbance experiments with one system. With high sensitivity and low noise, the IsoPlane 81 will ensure capture of almost all information present in the system.
Reflection is the process by which electromagnetic radiation is returned either at the boundary between two media surface reflection or at the interior of a medium volume reflection , whereas transmission is the passage of electromagnetic radiation through a medium.
Both processes can be accompanied by diffusion also called scattering , which is the process of deflecting a unidirectional beam into many directions. In this case, we speak about diffuse reflection and diffuse transmission Fig. When no diffusion occurs, reflection or transmission of a unidirectional beam results in a unidirectional beam according to the laws of geometrical optics Fig.
In this case, we speak about regular reflection or s pecular reflection and regular transmission or direct transmission. Reflection, transmission and scattering leave the frequency of the radiation unchanged.
Exception: The Doppler Effect causes a change in frequency when the reflecting material or surface is in motion. Absorption is the transformation of radiant power to another type of energy, usually heat, by interaction with matter. In general, reflection, transmission and absorption depend on the wavelength of the affected radiation.
Thus, these three processes can either be quantified for monochromatic radiation in this case, the adjective "spectral" is added to the respective quantity or for a certain kind of polychromatic radiation. For the latter, the spectral distribution of the incident radiation has to be specified.
In addition, reflectance, transmittance and absorptance might also depend on polarization and geometric distribution of the incident radiation, which therefore also have to be specified. The reflectance r is defined by the ratio of reflected radiant power to incident radiant power. Total transmittance is further subdivided in regular transmittance t r and diffuse transmittance t d , which are given by the ratios of regularly or directly transmitted radiant power and diffusely transmitted radiant power to incident radiant power.
Being defined as ratios of radiant power values, reflectance, transmittance and absorptance are dimensionless. Quantities such as reflectance and transmittance are used to describe the optical properties of materials.
The quantities can apply to either complex radiation or to monochromatic radiation. Descriptions of the principle measurements are presented in paragraph III.
Radiance coefficient q e , Bidirectional reflectance distribution function BRDF The radiance coefficient q e characterizes the directional distribution of diffusely reflected radiation. In detail, the radiance coefficient depends on the direction of the reflected beam and is defined by the ratio of the radiance reflected in this direction to the total incident irradiance.
In general, the reflected radiance is not independent from the directional distribution of the incident radiation, which thus has to be specified. The only difference is that the BRDF is a function of the directions of the incident and the reflected beam Fig. However, its advantage is the simultaneous description of the material's reflection properties for all possible directional distributions of incident radiation, whereas the radiance coefficient generally is valid for just one specific directional distribution of incident radiation.
The BRDF depends on the directions of incident and reflected radiation, which are given by the angles J i and J r , which are measured relative to the reflecting surface's normal, and the azimuth angles j i and j r , which are measured in the plane of the reflecting surface. Gigahertz-Optik Inc. Contact info-us gigahertz-optik.
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