Dual fiber coupled laser-driven light sourceZhou, Jing; Wang, Qingsong; Foley, Neal; Schiller, Craig; Zhu, Huiling
doi: 10.1117/12.2677768pmid: N/A
Laser-driven light sources (LDLS) have been gaining popularity in semiconductor metrology and spectroscopic measurement in the past 20 years because of their much higher brightness across a broad spectral range with higher stability than traditional electrode-based lamps. In addition, fiber-coupled LDLS systems offer more flexibility and convenience than free-spaced ones. However, due to the limited NA of fiber coupling optics, only light output from one side of a Xe plasma bulb is coupled to the fiber port, with light emitted into the opposite side of the Xe bulb wasted. To address this issue, a dual fiber coupling system is designed and implemented to collect the photons from both sides of a Xe plasma bulb. This paper will present the optical design of EQ-99 based LDLS lamp head with two fiber-coupled ports, the elliptical mirror alignment and optimization, and the performance of both fiber ports’ output, including power spectrum, beam profile, and stability. Besides the total light power from two fiber ports being nearly doubled with the same laser power driver, the mirror coatings and output windows can be individually configured and optimized for different spectral ranges, which can be useful for broadband applications. One good example is its integration into the extended range CSE system to obtain a decent output flux covering 350 to 1100nm.
View rotation spectaclesLocher, Maik; Courtial, Johannes
doi: 10.1117/12.2676739pmid: N/A
We propose novel medical spectacles with the aim to aid in the treatment of torsional diplopia. Using a pixelated approach these may be light, compact and cheap to produce. We found that for a large field of view, or when far from the eye these work well. There was a significant reduction in view quality when close to the eye, especially for the central field of view.
Method of polarization-maintaining photonic crystal fiber nonlinear response measurement using phase shift between orthogonal polarization modesKuliešaitė, Miglė; Pimpė, Jokūbas; Vengelis, Julius; Jarutis, Vygandas
doi: 10.1117/12.2676373pmid: N/A
Nonlinear refractive index n2 is the material parameter, which is used to describe the strength of phenomena caused by third-order nonlinearity, so measuring it accurately is one of the key tasks of nonlinear optics. Several techniques to estimate n2 of the PCF have been demonstrated, but for example Z-scan is not suitable for any type optical fibers, because this method only allows to estimate n2 of the material preform of the PCF. Other methods, such as four-wave mixing, self-phase modulation, cross-phase modulation allow qualitatively good estimation of n2 only when pump wavelength is close to the zero dispersion wavelength (ZDW) of the optical fiber. In this paper, we present a new method of polarization-maintaining photonic crystal fiber nonlinear refractive index measurement using phase shift between orthogonal polarization modes.
New patterned silicon wafer shape metrology systemKurtev, Kiril Ivanov; Trujillo-Sevilla, Juan M.; Castro Luis, Guillermo; Jiméneza, Miguel; Abrante, Rubén; Ramos-Rodríguez, José Manuel; Gaudestad, Jan O.
doi: 10.1117/12.2678349pmid: N/A
On-product overlay (OPO), with its continually shrinking overlay budget, remains a constraint in the continued effort at increasing device yield. Overlay metrology capability currently lags the need for improved overlay control, especially for multi-patterning applications. The free form shape of the silicon wafer is critical for process monitoring and is usually controlled through bow and warp measurements during the process flow. As the OPO budget shrinks, non-lithography process induced stress causing in plane distortions (IPD) becomes a more dominant contributor to the shrinking overlay budget. To estimate the wafer process induced IPD parameters after cucking the wafer inside the lithographic scanner, a high-resolution measurement of the freeform wafer shape of the unclamped wafer is needed. The free form wafer shape can then be used in a feed-forward prediction algorithm to predict both intra field and intra die distortions, as has been published by ASML, to minimize the need for alignment marks on the die and wafer and allows for overlay to be performed at any lithography layer. Up until now, the semiconductor industry has been using Coherent Gradient Sensing (CGS) interferometry or Fizeau interferometry to generate the wave front phase from the reflecting wafer surface. The wave front phase is then used to calculate the slope which again generates a shape map of the silicon wafer. However, these techniques have only been available for 300mm wafers. In this paper we introduce Wave Front Phase Imaging (WFPI), a new technique that can measure the free form wafer shape of a patterned silicon wafer using only the intensity of the reflected light. In the WFPI system, the wafer is held vertically to avoid the effects of gravity during measurements. The wave front phase is then measured by acquiring only the 2- dimensional intensity distribution of the reflected non-coherent light at two or more distances along the optical path using a standard, low noise, CMOS sensor. This method allows for very high data acquisition speed, equal to the camera’s shutter time, and a high number of data points with the same number of pixels as available in the digital imaging sensor. In the measurements presented in this paper, we acquired 7.3 million data points on a full 200mm patterned silicon wafer with a lateral resolution of 65μm. The same system presented can also acquire data on a 300mm silicon wafer in which case 16.3 million data points with the same 65μm spatial resolution were collected.
A 380-1100nm spectrum matching light source with high spectral resolution, throughput, speed, and stabilityWang, Qingsong; Saito, Kosuke; Zhou, Jing; Cutler, Alex; Grube, William; Schiller, Craig; McDaniel, Don; Gustafson, Debbie; Zhu, Huiling
doi: 10.1117/12.2677783pmid: N/A
A broadband spectrum matching light source with a visible to near-infrared (NIR) wavelength range is a valuable tool for broad applications. Based on Energetiq’s early version of spectrum matching light source covering the visible wavelength range (380 to 800nm), we extended the range of spectral matching to 1100nm. The new source has two input beam channels for the visible and NIR light from a single Energetiq LDLS light source. The two beams share the same grating, the digital mirror device (DMD), and the optical path. This innovative design extends the wavelength range with a smooth spectral transition. The new system has a compact system size with a 6.5mm diameter liquid light guide output. The light source has a 5.3nm full-width-half-maximum (FWHM) linewidth from 380 to 800nm and about 11nm FWHM between 680 and 1100nm, based on the input fiber size selection. With its high resolution, the source can be a valuable tool for sensor calibration, hyperspectral imaging, spectroscopy, and biomedical-related applications, which also need to consider the ambient light or NIR light effects and simulate the detailed spectral profiles of arbitrary light sources with more extended wavelength range and high fidelity. The source throughput, switching speed, and output stability will also be discussed.
Optical fiber-based novel quasi-distributed pressure sensingZhong, Shuda; Sharma, Jyotsna; Chen, Kevin
doi: 10.1117/12.2677901pmid: N/A
Reliable and accurate pressure measurement is critical for a variety of applications where regulating flow, volume, and product quality are essential for ensuring safe operation. Traditionally, pressure is measured using gauges. While offering a cost-effect measurement solution, pressure gauges suffer from many limitations, such as frequent calibration needs, low tolerance in harsh environments, and the ability to only provide pressure at the discrete gauge location. To overcome the limitations of conventional pressure gauges, this study describes the development and demonstration of a quasi-distributed optical fiber-based distributed pressure sensor using fiber Bragg-gratings (FBGs) inscribed in a single fiber. The sensor assembly was experimentally demonstrated to show pressure-induced wavelength change that was quantified to successfully estimate pressure for different pressure conditions. The results are validated with finite element method-based numerical simulation.
Tapered optical fiber sensor of acid and alkaline solution with MWCNT and alizarin red SRico-Mendez, M. A.; Selvas-Aguilar, R.; Montano-González, G. A.; Kharissova, O. V.; Toral-Acosta, D.; Puente-Ramírez, N. P.; Martínez-Rios, A.; Kharissov, B. I.; Arévalo, L. J.
doi: 10.1117/12.2683629pmid: N/A
This work introduces a pH detector based on a Mach-Zehnder Interferometer (MZI) designed to operate in pH 4.0, 7.0, and 10.0 buffer solutions. The sensor utilizes the monitoring for a particular solution comprising Alizarin Red S and OH carbon nanotubes at a wavelength of 1559 nm.
Photochromic gemstone analysis using in situ absorption spectroscopyTsai, Tsung-Han; D’Haenens-Johansson, Ulrika F. S.; Wang, Zhen
doi: 10.1117/12.2672807pmid: N/A
Photochromic gemstones exhibit optically controllable coloration at ambient temperatures, strongly affecting their visual appearance and potential market value. As a result, a comprehensive study of characteristic photochromic properties is required to estimate the potential influence on gemstone evaluation. A UV-Visible absorption spectrometer integrating a tunable light source for external excitation has been developed to investigate the wavelength- and time-dependence of photochromism for colored gemstones, focusing on natural, laboratory-grown, and color-treated pink diamonds. The results can be used to develop a color stabilization protocol to improve the reliability of color grading for valuable gemstones.
NUV and DUV high-magnification unified lens objectives: optical designFrolov, Dmitry N.; Vinogradova, Olga A.; Frolov, Alexey D.; Pavlii, Alexandr D.
doi: 10.1117/12.2678322pmid: N/A
The operation of the optical system in the short-wave part of the optical spectrum makes it possible to increase the value of the resolution. This is relevant for microscopy using lens objectives. It is proposed to design the monochromatic microscope optics for use in NUV and DUV spectral ranges. Also an increase in the resolution is possible when using immersion, for example, water. Upon reaching increased values of resolution, it is necessary to increase the scale of the image obtained on the microscope. The unification of structural parameters for the same type of lens objectives operating in a given spectral range becomes an original engineering solution.