Search

Regulatory T (Treg) cells are a specialized CD4+ T cell subpopulation that are essential for immune homeostasis, immune tolerance, and protection against autoimmunity. There is evidence that sex-steroid hormones estrogen and progesterone modulate Treg cell abundance and phenotype in women. Since natural oscillations in these hormones are modified by hormonal contraceptives, we examined whether oral contraception (OC) use impacts Treg cells and related T cell populations. T cells were analyzed by multiparameter flow cytometry in peripheral blood collected across the menstrual cycle from healthy women either using OC or without hormonal contraception and from age-matched men. Compared to naturally cycling women, women using OC had fewer Treg cells and an altered Treg cell phenotype. Notably, Treg cells exhibiting a strongly suppressive phenotype, defined by high FOXP3, CD25, Helios, HLADR, CTLA4, and Ki67, comprised a lower proportion of total Treg cells, particularly in the early- and mid-cycle phases. The changes were moderate compared to more substantial differences in Treg cells between women and men, wherein women had fewer Treg cells—especially of the effector memory Treg cell subset—associated with more T helper type 1 (Th1) cells and CD8+ T cells and lower Treg:Th1 cell and Treg:CD8+ T cell ratios than men. These findings imply that OC can modulate the number and phenotype of peripheral blood Treg cells and raise the possibility that Treg cells contribute to the physiological changes and altered disease susceptibility linked with OC use.

The spatial frequency response, height sensitivity and system noise of a scanning common-path interferometer have been studied. The impulse response function and the frequency transfer function of the system are obtained analytically using Fresnel diffraction integral. Experimental results are also given. The results show that the system covers a broad spatial frequency range from 2 X 10-5/micrometer to 3/micrometer. The height sensitivity of the system is better than 0.01 angstrom. System stationary noise less than 0.1 angstrom RMS is achievable without additional noise reduction post-process. Measurement of an ultra-smooth silicon substrate with a sub-angstrom roughness is successfully demonstrated. Measurement of a smooth glass substrate is also shown.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The measurement of surface roughness is typically an important parameter for describing the quality of fine fmishedparts. Examples include measurements of finely polished flat and curved optics, computer hard disks, semiconductorwafers and optical disks. Most often an RMS or R roughness value is reported for the part. Roughness is typicallyused to describe the high spatial frequency (or short spatial wavelength) components. For example, lower roughnessvalues for optical parts typically results in less scattering. Three basic user defined surface profiles can be used to

The measurement of surface roughness is typically an important parameter for describing the quality of fine finished parts. Examples include measurements of finely polished flat and curved optics, computer hard disks, semiconductor wafers and optical disks. Most often an RMS or RA roughness value is reported for the part, typically by the high spatial information. Other surface information can also be of interest, including mid-spatial roughness and figure information. Three basic surface profiles are generally used to define the surface, including total profile, waviness and roughness. A different approach is to examine the spatial information on the surface by using the power spectrum or the autocovariance function. Both of these functions can be calculated over any user selected spatial frequency region.

This paper presents a general method for measuring the frequency response of a surface profiling instrument. One important consequence of this work is the discussion of the importance of the modification of surface spatial frequencies by the measuring instrument. The method uses a step height sample to characterize the impulse instrument, and power spectrum response. Experimental measurements are shown for a variety of focusing objectives. The results show that the half power bandwidth provides a good characterization of the high spatial frequency limit of a surface profiler.

A CCD camera system has been added to a surface profiler to display Nomarski enhanced images of a surface under test. The viewing system provides an expanded view of the test surface for identifying the location and extent of surface features. Practical engineering considerations of the optical and illumination systems will be discussed. Also, examples of surface images and their respective profile scans will be shown.

Microroughness for profile lengths of 1 mm or less can be measured with several very sensitive mechanical contact and optical noncontact instruments.1-5 These instruments are sensitive enough to measure roughnesses of less than 1 Å rms. Lateral resolutions vary from a few tenths of a micron for a mechanical contact type instrument1,2 to one or more microns for optical non-contact profilers.3-5 The best polished optical surfaces have microroughnesses of less than 10 Å rms, and values of 1 - 2 Å rms have been measured for specially polished samples of Zerodur, silicon carbide, and sapphire2. On the other hand, optical figure measurements are routinely made on samples ranging from diameters of a few centimeters to several meters. Flatness of a few hundredths of a wavelength of visible light can be achieved in the best cases. For example, an rms figure error of one hundredth of a wavelength at a wavelength of 5000 Å is 50 Å.

This paper describes the implementation of an automatic focus control system (Autofocus) to an optical non-contact surface profiling instrument. Such a focus control system extends the operation of the surface profiler to measurements of both roughness and figure that would otherwise be limited by the optical systems depth of focus. Measurement results are presented from a variety of curved samples.

Two types of interferometers and a mechanical stylus-type instrument have been used to make surface profile measurements on the same samples. All had comparable height sensitivities, of the order of 1 Å rms, but different lateral resolutions. The Optel profilometer1 is based on the principle of the Nomarski differential interference contrast microscope in which two beams of light separated by 0.3 μm are measured by two detectors. Values of the surface slope are calculated from the detector signals; integration yields a surface profile. The Wyko heterodyne profilometer2 is based on the Mireau interferometer. One light beam is reflected from the sample while a second beam is diverted by a beam splitter to a reference mirror located between the microscope objective lens and the sample. A 1024 element linear diode array measures the phase of the interference fringe pattern which is then transformed into a surface profile. In the Talystep instrument3 a 1 μm radius diamond stylus contacts the surface with a 1-2 mg loading that is light enough not to damage the surface. The vertical motion of the stylus as it moves across the surface is converted into a digitized electrical signal that directly gives the surface profile. Results of measurements made on different types of surfaces using the three instruments will be compared to show repeatability, height sensitivity, and lateral resolution. Special features of each instrument will also be discussed.

This paper presents a description of the design and testing of a precision surface microprofiler. The instrument's basic design has been reported at previous conferences (References 1 and 2). This paper will emphasize more specific details of the microprofiler's optical and other system components. Emphasis will be made on describing the elements that influence the resolution of the instrument.

This paper presents surface roughness measurements for a variety of surfaces using an automated Nomarski type profiling instrument. The instrument provides a quantitative measure of the surface slope and surface roughness of a surface. The vertical resolution of the Nomarski technique allows surface height evaluation with a resolution of one Angstrom and a lateral resolution of approximately one micron. A scan length of up to 100 millimeters can be used. The profiling instrument measures slope and calculates the surface profile. Both slope and profile descriptions of the surface are useful in examining the topography of the surface. Examples of the surfaces presented include a laser gyro mirror and a diamond turned mirror. Statistical surface parameters are shown for these surfaces, including the power spectrum and the autocovariance function. The statistical parameters are calculated from the both the slope and profile data with a comparison of the results.

This paper presents measurements of surface features from a variety of surfaces using a non-contact, long scan surface profiler. Data is presented emphasizing the waviness and roughness of the surface. Several different types of samples are presented, including the surface of a diamond turned mirror, computer hard disk, machine tool surface, and film. The instrument used for these measurements has a resolution of 1 Angstrom and has a scan length up to 100 millimeters.