Ellipsometer automatic

H. Takasaki. Automatic Ellipsometer. Automatic Polarimetry by Means of an ADP... 

The availability of automatic ellipsometers56 greatly helps all this. It is possible to program the ellipsometer to print a readout of, for example, refractive index and thickness as a function of potential. The technique could be applied more widely, a developmental possibility being that it could enable the operator to follow changes in spectra (and thus interpret what molecular changes cause them) in the millisecond range. One of the frontiers of development of techniques in electrochemistry could be the use of ellipsometric spectroscopy. 

By automatic is meant ellipsometers that calculate n and 1 directly (and in a short time) from the measurement of A and t. 

The thickness of the synthesized brashes was determined by means of ellipsometry performed on a COMPEL Automatic Ellipsometer (InOm Tech, Inc.) at a fixed 70o incidence angle. Refractive index for all polymers was asstrmed to be 1.5. Strrface characterization was performed by Scanning Probe Microscopy (SPM) in tapping mode on a Dimension 3100 microscope (Digital Irrstruments, Veeco ). Static contact angle measurements were made using a... 

A further type of fast automatic ellipsometer for electrochemical investigations has been described [933] and an experimental approach to observe fast transients with ellipsometry was reported [934]. In the photometric mode, the intensity of the reflected light is measured as a function of the position of polarizer and sometimes compensator in the incoming beam for further details and an overview, see [934]. A general overview of instrumental developments has been provided [935]. 

The eUipsometer used was a Rudolph Research ellipsometer (M el 43603) modified for automatic null-ellipso-metry. All measurements were performed without drying of the silicon slides. 

Historically, the most important type of instrument has been the classical null ellipsometer, although today this has been superseded by the automatic spectroscopic ellipsometer (SE), which can take measurements over a wide range of... 

In 1960s, in order to reduce the time spending in angle calibration, H. Takasaki [11] used automation servomotor technology to drive polarizer and compensator and set the azimuth of polarizers automatically. However, in this configuration, it was still unavoidable to use human eye in the azimuth reading. Of course, the subsequent ellipsometry data processing was still involved in the human. So this type of ellipsometer was only a semi-automatic ellipsometer. 

R. W. Stobie, B. Rao, and M. J. Dignam, Automatic ellipsometer with high sensitivity... 

Welin-Klinstroem et al used a null ellipsometer equipped with an automatic sample scanning device for studies of adsorption and desorption of fibrinogen and IgG at the liquid/solid interface on surface wettability gradients on silicon wafers. To follow the processes along the wettability gradient, off-null ellipsometry was used. The kinetics of adsorption and nonionic-surfactant-induced desorption varied considerably between fibrinogen and IgG. In the hydrophilic region, veiy little protein desorption was seen when a nonionic surfactant was used. 

This modified ellipsometry is the combined reflectance-ellipso-metry technique, also known as the three-parameter ellipsometry (TPE) in contrast to the conventional two-parameter ellipsometry. Since it was first introduced in 1971 by Paik and Bockris to study passivation film formed anodically on cobalt, TPE has proven to be a powerful technique for determining all three unknowns from purely optical measurements alone. The measurements for A, and R are made with the same experimental setup as for the conventional ellipsometer, with minor modifications of the measurement routine if necessary. Here, R is the reflectance at the same angle of incidence as for the A and if/ measurements. Therefore, no alignment change is necessary for additional measurement of R. With some automatic ellipsometers (see Section III.5), all three measurements can be recorded simultaneously. It should be emphasized once more that A, ij/, and R are mutually independent functions, despite the fact that both il/ and R are defined by combinations of and r. ... 

Another important type of automatic ellipsometer uses modulation of the light polarization to achieve self-nulling. Figure 6 shows one such automatic ellipsometer designed by Paik et Special... 

Figure 6. A self-nulling automatic ellipsometer with a reflectance-recording facility A = analyzer AD = adder amplifier C = compensator D = photodetector FC = Faraday coil around a Nd glass rod I = integrator LIA = lock-in amplifier LS = He-Ne laser P = polarizer PA = phase adjuster PS = phase shifter PW = power amplifier REC = recorder RA = ratio amplifier S = beam splitter SG = 1-kHz signal generator SS = sample surface. (From Ref. 28, with permission from Elsevier Science Publishers.)...

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