Laser pressure catapulting of adherent cells directly or cells grown on micropallets are two common methods of dislodgement. We describe a method where laser catapulting is performed as a flow is introduced orthogonally in a simple capillary chamber that is inexpensive and obviates flow-generating devices. The moving cells terminate near the contact line within the liquid medium, ensuring that they remain continuously hydrated and where the surface-tension forces hold them in place to permit a later collection process with a receptacle. By dislodging the cells close to the free edge of the liquid chamber, the amount of cell travel and, thus, contamination is minimized. The metrics of cell death and movement show that firing of the laser beam center a distance away from the cell to create a bubble that cavitates over time is more viable with the technique than directly on the cell.
Two aspects of electroplated gold that are often inspected on are plating thickness, and verification of gold presence at
desired regions. With the later, in-situ reporting is desired. In this work, 8 color spaces - RGB, rgb, I1I2I3, HSI, YUV,
YIQ, XYZ, and L*a*b* - were investigated to differentiate between regions with and without electroplated gold. It was
found that the r, b, I2, H, U, V, I, Q, Z, and b* color space components provided distinct two level differentiability; while
the R, G, and S color space components permitted differentiation at non distinct two levels. It was also uncovered that
grayscale imaging would not permit any form of differentiation. The findings here indicate feasibility in using machine
vision in tandem with color space analysis for electroplated gold inspection.
There is a need to ensure that light-emitting diodes (LEDs) are performing well as they are increasingly used in demanding applications. In this work, we present an adapted usage of flatbed scanners to inspect LEDs. This offers the benefits of lower cost and higher measurement throughput than specialized equipment like goniophotometers. The technique is demonstrated to detect LED encapsulation defects, to identify low illumination and misaligned LEDs in arrays, and to evaluate angular color nonuniformity of white LEDs.
Aplanatic optics crafted from transparent dielectrics can approach the etendue limit for radiative transfer in pragmatic
near-field systems. Illustrations are presented for the more demanding realm of high numerical aperture (NA) at the
source and/or target. These light couplers can alleviate difficulties in aligning system components, and can achieve the
fundamental compactness limit for optical devices that satisfy Fermat's principle.
Practical aplanatic optics crafted from transparent dielectrics can approach the thermodynamic limit for radiative transfer in near-field systems. Designs are presented for the particularly challenging realm of high numerical aperture (NA) at the source and/or target. These light couplers can alleviate difficulties in aligning system components and can achieve the fundamental compactness limit for optical devices that satisfy Fermat's principle. Examples and performance estimates based on ray-trace simulations are presented.
Good alignment is needed in various wafer processes. Reflectometry is a well-established technique that continues to be widely used to monitor the thickness of wafer thin films. The use of a reflectometer was investigated to detect incorrect tilt and height of wafer placement. We found that it could be used in the spectroscopic or the monochromatic mode and provided results whether the wafer was bare or coated. We also found that the technique was somewhat more sensitive to tilt of bare wafers, and more sensitive to height displacements of coated wafers.
Temporal fringe pattern analysis is invaluable in transient phenomena studies but necessitates long processing times. Here, we describe a parallel computing strategy based on the single program multiple data (SPMD) model and hyper-threading processor technology to reduce the execution time. In a two-node cluster workstation configuration, we found that execution periods reduced by 1.6 times using four virtual processors. To allow even lower execution times with increasing number of processors, the time allocated for data transfer, data read, and waiting should be minimized. Parallel or super computing is found here to present a feasible approach to reduce execution times in temporal fringe pattern analysis.
The traditional method for calibrating angular indexing repeatability of rotary axes on machine tools and measuring equipment is with a precision polygon (usually 12 sided) and an autocollimator or angular interferometer. Such a setup is typically expensive. Here, we propose a far more cost-effective approach that uses just a laser, diffractive optical element, and CCD camera. We show that significantly high accuracies can be achieved for angular index calibration.
Interferometry is increasingly used in transient phenomena studies. Temporal fringe pattern analysis is ideal for this form of study but necessitates large data storage. Current compression schemes do not facilitate efficient data retrieval and may even result in important data loss. Here, we describe an encoding scheme that results in low crucial data loss and performs temporal fringe analysis at the same time. From the encoded data, intensity fringe patterns and phase maps can be retrieved with ease. The scheme is demonstrated here with simulated wavefront interferometry temporal fringe patterns albeit it portends usage in other forms of fringe-based techniques as well.
Dye-based pressure sensitive films are advantageous in plantar pressure studies due to their of ease of use, costeffectiveness, and ability to produce measurements within the shoe. To circumvent the use of proprietary equipment and software to relate the dye stained film to load, an alternative approach of using a conventional flatbed scanner and generic image processing software is attempted here instead. The technique revealed high linear increasing and decreasing trends for the respective red and blue normalized intensities (correlation coefficient > 0.95) and low standard deviation in all readings (< 0.06) overall. By subtracting the blue from the red normalized intensity, it was discovered that the measurement sensitivity could be doubled. The results here confirm the viability of using a conventional flatbed scanner and generic image processing software to relate the dye stained pressure films to load. The adoption of this approach promises substantial cost savings.
Optical deflection sensing is perhaps the most widely used scheme in atomic force microscopy. In this technique, the sensor is a quadrant photodiode. Position detection is essentially achieved using voltage differencing between the photodiode outputs. To improve data throughput, this is often done using operational amplifiers in the differencing mode. The measurement sensitivity is affected by environmental noise. Intensity modulation is a simple method of overcoming environmental noise. When this scheme is applied to the optical deflection sensor technique, random chaotic signals were found to form. Unless expensive filtering methods are introduced, the efficacy of using intensity modulation to reduce the effects of environmental noise in the optical deflection sensing method is limited.
Temporal fringe pattern analysis is gaining prominence in interferometry; in particular for transient phenomena studies. This form of analysis, nevertheless, necessitates large data storage. Current compression schemes do not facilitate efficient data retrival and may even result in important data loss. Here, we describe a novel compression scheme that does not result in crucial data loss and allows the efficient retrieval of data for temporal fringe analysis. In sample tests using digital speckle inferometry or fringe patterns of a plate and of a cantilever beam subjected to temporal phase and load evolution respectively, a compression ratio of 1.6 was achieved without filtering out any data from discontinuous and low fringe modulation spatial points. By eliminating 38% of the data from discontinuous and low fringe modulation special points, a very significant compression ratio of 2.4 was attained.
A through-beam configuration optical sensor is designed, fabricated, and tested for chip bonding. The tip taper angle was designed based on a cone condensor theory for maximal optical power collection at the tip's output. Experiments conducted to determine the optical power collected using a series of tip taper angles confirm the general applicability of the cone condenser theorem. The optical sensor was found to perform extremely well when incorporated in an actual chip bonding machine, where chips of 3.4×3.4 mm in dimension were tested.
The use of charge-coupled devices (CCDs) for imaging in digital shearography necessitates the knowledge of their electronic (signal-independent) noise level, as the visibility of fringes produced is dependent on this factor. A method based on measuring the experimental CCD noise variance to construct a linear equation system is presented. From the solution of this equation system, the electronic noise level of a particular CCD used for imaging can be determined. Evaluation of CCDs based on this noise factor allows the performance of each CCD used in digital shearography to be compared.
Shearing speckle interferometry using the wedge arrangement yields displacement derivative fringes that are modulated by in-plane displacement fields. In this paper, it is found that using a biprism instead of a wedge suppresses the in-plane displacement modulation effect without affecting the visibility of the displacement derivative fringes.
The transmission function of a double-exposure shearing specklegram consists of fringe- bearing and non-fringe bearing components. To obtain interference fringes, spatial filtering is performed on the processed specklegram to allow only the fringe-bearing components to pass. The spatial frequency for filtering is often determined on a trial-and-error basis. In this paper, a technique is presented to obtain a spectral distribution from which the optimum spatial filtering frequency can be deduced. Knowledge of the optimum spatial filtering frequency to recording aperture relationship enables better selection of image recording conditions.