Common-path interferometer

Abstract: We present a full-field phase microscopy technique for quantitative nanoscale surface profiling of samples in reflection. This technique utilizes swept-source optical coherence tomography in a full-field common path interferometer for phase-stable cross-sectional acquisition without scanning. Subwavelength variations in surface sample features are measured without interference from spurious reflections by processing the interferometric phase at a selected depth plane, providing a 1.3 nm stability for high signal-to-noise ratio surface features. Nanoscale imaging was demonstrated by measuring the location of receptor sites on a DNA assay biochip and the surface topography of erythrocytes in a blood smear.

Abstract: We present a full-field phase microscopy technique, motivated by swept-source Fourier-domain optical coherence tomography, for quantitative nanoscale two-dimensional profiling of sample surfaces and internal structures. The optical configuration consisted of a common path interferometer, illuminating the sample with a collimated beam and detecting the back-scattered light on a 2D CCD camera. A tunable fiber Fabry Perot filter was used to sweep a narrow band (0.07nm) through the 47nm FWHM bandwidth of a superluminescent diode source. The full field of view was recorded for each discrete wavelength step, generating a spectrally indexed interferometric data cube mapping each pixel to a point on the sample. A three dimensional volume was generated by performing the discrete Fourier transform along the spectral axis. Sub-coherence length variation across a depth slice was obtained by examining the phase of the Fourier transformed data set at the selected depth. The phase stability of the system was measured to be 1.3nm for high SNR surface features. The nanoscale imaging potential of this system was demonstrated by measuring the height of patterned chrome on a USAF resolution target, the location of receptor sites on a DNA assay biochip, and the surface topography of erythrocytes in a blood smear.

Abstract: The measurement of intense E-fields is a fundamental need in various research areas. Integrated optical E-field sensors (IOESs) have important advantages and are potentially suitable for intense E-field detection. This paper comprehensively reviews the development and applications of several types of IOESs over the last 30 years, including the Mach-Zehnder interferometer (MZI), coupler interferometer (CI) and common path interferometer (CPI). The features of the different types of IOESs are compared, showing that the MZI has higher sensitivity, the CI has a controllable optical bias, and the CPI has better temperature stability. More specifically, the improvement work of applying IOESs to intense E-field measurement is illustrated. Finally, typical uses of IOESs in the measurement of intense E-fields are demonstrated, including application areas such as E-fields with different frequency ranges in high-voltage engineering, simulated nuclear electromagnetic pulse in high-power electromagnetic pulses, and ion-accelerating field in high-energy physics.