Projection Lens Research Articles

Compensated differential Zernike fitting method for wavefront aberration metrology based on grating lateral shearing.

Lateral shearing based on the grating is one of the classical configurations when measuring the wavefront aberration of optical systems such as the lithographic projection lens. Because the wavefront under test is spherical, but a detector surface is a plane, the coordinate of the wavefront surface will be distorted on the detector surface. As the numerical aperture (NA) of the optics under test increases, the shear ratios at different positions within the shearing region are significantly different due to the coordinate distortion. Therefore, the reconstructed wavefront from the traditional lateral-shearing reconstruction method designed for a fixed shearing ratio will contain a non-negligible error. In this work, we use the ray-tracing method to calculate the shearing ratio distribution in the shearing region and propose a compensated differential Zernike fitting method to solve the coordinate distortion and shearing ratio variation problem. The relative error of the uncompensated result will increase as the NA increases. This error is around 1% for a 0.1 NA, 10% for a 0.3 NA, and over 100% for an NA above 0.7. Compensation for the shearing ratio variation is necessary when the NA is larger than 0.3. The proposed method has been validated by simulations and experiments.

Aberration analysis and compensate method of fully connected neural network in deep ultraviolet lithography

Thermal aberration of a projection lens is caused by lens heating and leads to degradation of image quality. Two tasks have been undertaken in this article: first, analysis of the impact of single aberration on imaging quality, and second, use of machine learning to calculate the combination of Zernike aberration coefficients to reduce the influence of aberration on the process window. The impact of aberration on deep ultraviolet (DUV) lithography imaging has been analyzed separately for 16 Zernike terms. The influence of single Zernike coefficient on depth of focus, mask error enhancement factor, and image log slope is comprehensively analyzed by source mask optimization. However, more than one Zernike term is present in the aberration of a real DUV optics. A fully connected neural network (FCNN) model based on machine learning is widely used in the screening of multivariate experiments and can solve the problem of the large number of input variables and the random values of the input data. Its network structure is simple to debug, with fast screening speed and high precision. To make reasonable budget for aberration, an FCNN model is used to find some combinations of Zernike coefficients for different lithographic performance indicators. This implies that the FCNN model has the ability to select a better Zernike combination while each individual Zernike term value falls in the range of −30 to 30 mλ, which plays a guiding role in DUV optics design.

Rigidity through a Projective Lens

In this paper, we offer an overview of a number of results on the static rigidity and infinitesimal rigidity of discrete structures which are embedded in projective geometric reasoning, representations, and transformations. Part I considers the fundamental case of a bar–joint framework in projective d-space and places particular emphasis on the projective invariance of infinitesimal rigidity, coning between dimensions, transfer to the spherical metric, slide joints and pure conditions for singular configurations. Part II extends the results, tools and concepts from Part I to additional types of rigid structures including body-bar, body–hinge and rod-bar frameworks, all drawing on projective representations, transformations and insights. Part III widens the lens to include the closely related cofactor matroids arising from multivariate splines, which also exhibit the projective invariance. These are another fundamental example of abstract rigidity matroids with deep analogies to rigidity. We conclude in Part IV with commentary on some nearby areas.

Directionally Decomposing Structured Light for Projector Calibration.

Intrinsic projector calibration is essential in projection mapping (PM) applications, especially in dynamic PM. However, due to the shallow depth-of-field (DOF) of a projector, more work is needed to ensure accurate calibration. We aim to estimate the intrinsic parameters of a projector while avoiding the limitation of shallow DOF. As the core of our technique, we present a practical calibration device that requires a minimal working volume directly in front of the projector lens regardless of the projector's focusing distance and aperture size. The device consists of a flat-bed scanner and pinhole-array masks. For calibration, a projector projects a series of structured light patterns in the device. The pinholes directionally decompose the structured light, and only the projected rays that pass through the pinholes hit the scanner plane. For each pinhole, we extract a ray passing through the optical center of the projector. Consequently, we regard the projector as a pinhole projector that projects the extracted rays only, and we calibrate the projector by applying the standard camera calibration technique, which assumes a pinhole camera model. Using a proof-of-concept prototype, we demonstrate that our technique can calibrate projectors with different focusing distances and aperture sizes at the same accuracy as a conventional method. Finally, we confirm that our technique can provide intrinsic parameters accurate enough for a dynamic PM application, even when a projector is placed too far from a projection target for a conventional method to calibrate the projector using a fiducial object of reasonable size.

Lithography Solutions for Submicron Panel-Level Packaging

Abstract Heterogeneous Integration of logic, memory, photonic, analog and other value-adding functions is one approach for increasing electronic system efficiency, performance and bandwidth while helping reduce overall manufacturing costs. To capitalize on Heterogeneous Integration benefits, designers are requiring finer resolution Redistribution Layer patterning and larger package sizes to maximize System-in-Package integration possibilities. Production of large-package electronics systems is well-suited for Panel Level Packaging (PLP) and achieving uniform submicron patterning across the entire rectangular panel is a key lithography challenge. To meet this challenge, Canon developed the first lithography exposure system or stepper that is capable of achieving submicron resolution on 500 mm panels. The stepper features a panel handling system for processing panels up to 515 mm x 515 mm in size and is also equipped with wide-field projection lens featuring a maximum 0.24 Numerical Aperture and a large 52 mm x 68 mm image field. This paper will report on evaluation results for a submicron PLP process using the panel stepper and will introduce high-resolution PLP process challenges including warped panel handling. Process results on Copper Clad Laminate (CCL) substrates will be reported including pattern uniformity, adjacent shot stitching accuracy and overlay accuracy on substrates containing die-placement error that is common in Fan-Out processes.

Review of optical design for vehicle forward lighting based on white LEDs

We introduce a current development in optical design for vehicle forward lighting based on solid-state lighting, in particular, phosphor-converted white LEDs. The vehicles include bicycles, bikes, and automobiles. Although the requirements regulating different vehicles are different, the low beam always requires a high-contrast cutoff line. Three optical design approaches are discussed; these include a projection lens incorporated with a baffle or beam shaper, multisegment reflectors, and complex lenses. A new design approach called light field management technology for the multisegment reflector is introduced. In addition, the possible related manufacturing errors and the robustness of different optical approaches are analyzed. Finally, we introduce three approaches to adaptive forward lighting that provide a driver with brighter and clearer vision without inducing glare to people on the roadway. The application of video projection technology to roadway illumination could be a trend of vehicle forward lighting based on solid-state lighting.

Projection optical engine design based on tri-color LEDs and digital light processing technology.

Digital light processing (DLP) is currently a cutting-edge technology for desktop projection optical engines. Due to the passive luminescence characteristics, the DLP projection engine needs a few specific illumination optical components for light collimation, homogenization, and color combination, together with a projection lens matching the DLP chip and magnifying the image. In this paper, we propose a design approach that first splits the DLP projection optical engine into individual components for separate design, and then integrates them into a whole system for further verification. For the first step, the collimating lens group is designed for light collection, and the dichroic mirrors are used to fold the light path based on tri-color LED light sources. For the second step, a fly-eye lens and the corresponding relay lens group are designed to achieve uniform illumination on the DMD chip. The third step is to optimize the projection lens group for high-resolution projection display. Based on the design and simulation, the optical efficiency is 63.4% and the uniformity reaches 94.9% on the projection screen. The modulation transfer function (MTF) of the projection lens is higher than 0.4 at 66 lines for the distance of 500∼1500mm, and the distortion is lower than 1%. Simulation results show that the total luminous flux is estimated to reach 224.15 lm when the powers of tri-color LEDs are 21 W, 15.5 W, and 25 W, respectively. A projector prototype is built and tested for further verification, which provides a luminous flux of 220.43 lm and uniformity of 90.22%, respectively. The proposed design, demonstrated by both simulation and experiment, exhibits high feasibility and application potential in state-of-the-art commercial projector design.

Design of Refractive/Diffractive Hybrid Projection Lens for DMD-Based Maskless Lithography

The projection lens is the core component of DMD-based maskless lithography and its imaging quality directly affects the transferal of exposure pattern. Based on the traditional projection lens system, we have designed diffractive optical element (DOE) and aspheric surfaces to optimize the refractive/diffractive hybrid projection lens system to improve its imaging quality. We found that the best effect is obtained when DOE is very close to the front lens group before the diaphragm of the hybrid system. Compared with the traditional projection lens system, this hybrid projection lens system has lower wave aberration with the help of DOE, and higher image quality owing to the modulation transfer function (MTF) value being improved. Finally, a hybrid projection lens system with working distance of 29.07 mm, image Space NA of 0.45, and total length of 196.97 mm is designed. We found that the maximum distortion and field curvature are 1.36 × 10−5% and 0.91 μm, respectively.

Experimental evaluation of uncertainty in sub-nanometer metrology using transmission electron microscopy due to magnification variation

Uncertainties due to the magnification variation in sub-nanometer metrology using transmission electron microscopy (TEM) were experimentally evaluated by comparing the measured values of the (220) lattice spacing of a crystalline Si specimen acquired under various conditions. Interday variation of the magnification, intraday repeatability, rotation of the TEM image, specimen exchange, specimen position, defocusing, magnetic hysteresis of the lenses, projection lens distortion, and measurement errors were considered as the uncertainty components. The obtained results reveal that the major uncertainty components are the interday magnification variation, intraday repeatability involving nonuniformity of the specimen structure, magnetic hysteresis of the intermediate lenses, and projection lens distortion. Among these components, it is expected to be feasible to suppress the interday magnification variation to a negligible level by daily magnification calibration, suggesting that minimizing the uncertainties due to magnetic hysteresis of the intermediate lenses, projection lens distortion, and nonuniformity of the specimen structure will be the key factor for further reducing the uncertainty of sub-nanometer metrology using TEM. Furthermore, we found that magnification calibration using an appropriate reference material (e.g. the lattice fringes of crystalline Si) before every measurement should enables sub-nanometer metrology with a relative uncertainty of 3.2%, even if the specimen is introduced into the TEM system by specimen exchange after magnification calibration.

43‐3: Laser Assisted LED for High Output Automotive DMD Headlight

Most of ADB headlight engines are designed using blue LED or laser light sources for the exciting the phosphor conversion layer producing white light output. The phosphor conversion layers have been fabricated by silicone‐based phosphor, glass‐based phosphor, ceramic‐based phosphor, and single crystal‐based phosphor. Among these different phosphor materials, the single crystal phosphor (SCP) exhibits excellent thermal stability, better conversion efficiency, and high transparency to yellow light, but the required high‐temperature fabrication process, has been an impediment for widespread commercial production. Recently, the issues of higher fabrication temperature of the SCP have been overcome by using a novel design of single crystal growth to produce SCP with higher yield and better uniformity. In this study, the ADB headlight consists of a well‐developed, high efficiency, automotive qualified white LED, a TI digit mirror device (DMD), a projection lens, and a Laser‐Assist™ LED system using two laser diodes and a SCP plate. The SCP plates are fabricated by Czochralski technology at the high temperature of 1,940°C. Using the laser for the Laser‐Assist™ process, a 50% increase in the LED is obtained. This increase in output enables the increase in FOV and brightness of the ADB headlight, which results in significant improvement of the visibility and the illumination distance. The proposed advanced ADB headlight with ultra‐reliable SCP and Laser‐Assist™ LED system will become one of the most promising ADB headlight candidates for use in the next‐generation autonomous vehicle applications.

Design of projection optical system for 3D defect detection on PCB

According to the practical experience of PCB defect detection in semiconductor industry, a projection optical system suitable for structured light detection device is designed by using a DMD chip. In order to realize the lateral projection of structured light stripe and improve the quality of system projection, the design of tilt back group of projection lens is adopted and the projection size is 57×32mm.The simulation results show that the illumination uniformity of the projection system on the measured surface is more than 85%, the fringe contrast is larger than 0.5, and the maximum height of the measuring device is 5mm, which provides a guarantee for practical application of structured light fringe for 3D defect detection on PCB.

Jones pupil decomposition and its lithographic imaging impacts.

The Jones pupil is a full description of imaging properties of projection lenses in optical lithography. The decomposition of the Jones pupil into components with clear physical meanings was studied previously; however, the decomposition method has not been studied systematically. To generalize the existing decomposition method, this work is aimed at finding all the decomposition methods and analyzing the lithographic imaging impacts. In this work, six decomposition methods are proposed, and the lithographic imaging impacts of the Jones components are studied and compared for all the decomposition methods. The results demonstrate that, although the decomposition methods are different, their lithographic impacts are identical. To be specific, apodization has a dominant impact on the critical dimension with a magnitude of 1.3 nm, and the impact of diattenuation is 0.3 nm. In contrast, the impacts of the other Jones components of aberration, birefringence, rotator, and ellipticity are negligible. This work gives a complete understanding of the imaging impacts of the Jones pupil.

Теорія зменшення спеклів у лазерному проекторі дуже довгим багатомодовим волокном

Проаналізовано ефективність зменшення спеклів стаціонарним багатомодовим оптоволокном у лазерному проекторі. Розроблено та розраховано математичну модель для випадку дуже довгого оптоволокна. Комп’ютерне моделювання та аналіз математичної моделі показали, що коефіцієнт зменшення спеклів може з точністю придатною для інженерних розрахунків бути апроксимований як лінійна функція квадратного кореня відношення числової апертури лазерного проектора та ока. Дуже велика числова апертура, яка на кілька сотень перевищує зіницю людського ока, необхідна для зменшення спеклів нижче чутливості людського ока. Це випливає з того факту, що декореляція в методі використовує лише радіальний напрямок для зменшення спеклів. Для підвищення ефективності методу необхідна його модифікація, де буде передбачено використання азимутального напрямку.

Regularized Recursive Solutions for Prediction of Aberrations Associated With Projection Optics

For an improved reduction of thermally induced wavefront aberrations associated with the projection lens in deep ultraviolet lithography, this article proposes a regularization-based recursive linear estimation strategy for the model parameters of a predictive control scheme. The linearity of estimation is ensured by estimating only the gains of an approximate exponential regression model that effectively describes the spatial cooling behavior, where the time constants are preset to specific values such that the actual exponentials are collectively well described. Owing to its suitability for recursive formulations, the corresponding solution involves the celebrated Tikhonov regularization, with its regularization term additionally consisting of a scaling term that relates to the magnitudes of parameters so that the same regularization parameter can be used at different exposure settings and time moments. Moreover, for a proper tuning of this regularization parameter, the method of generalized cross-validation is adopted. By means of comparative analysis with respect to both synthetic and real data, the treated method is demonstrated to outperform the traditional Kalman filter, as well as nonlinear approaches such as the extended and unscented Kalman filters.

Community-School Partnerships as Racial Projects: Examining belonging for Newcomer Migrant Youth in Urban Education

The article conceptualizes community-school partnerships (CSP) as racial projects. Drawing on data from a mixed-methods study of how CSPs increase belonging for migrant youth, the article reveals existing tensions in CSPs from migrant youth ( N = 63) and stakeholder perspectives. Viewing CSPs through a racial project lens allows researchers and practitioners to identify, in both design and implementation, spaces of tension where attempts to disrupt the existing status quo and structure opportunity can ultimately reproduce inequality, especially given the “commonsense” logic of racial projects and coherence of neoliberal ones about belonging and immigrant integration. Implications for understanding CSPs as racial projects are discussed.

IMPLEMENTASI MEDIA VIDEO INTERAKTIF DALAM MATA PELAJARAN Al-QUR’AN DAN Al-HADITS DI MI DARUT TAQWA SENGONAGUNG PURWOSARI PASURUAN

Interactive Video Media in learning is a living image which is a picture in a frame where frame by frame is mechanically projected through the projector lens so that the screen looks alive. As with films, videos can depict an object moving together with natural sounds or sounds that are appropriate in learning.
 The formulation of the problems in this study are: 1. How is the implementation of interactive video media in the subject of al-Qur'an and al-Hadith at MI Darut Taqwa Sengonagung Purwosari Pasuruan? 2. What factors support and hinder the implementation of interactive video media in the subject of al-Qur'an and al-Hadith at MI Darut Taqwa Sengonagung Purwosari Pasuruan ?. The purpose of this study was to determine the implementation of interactive video media in the subject of al-Qur'an and al-Hadith and to determine the supporting and inhibiting factors for implementing interactive video media in the subjects of al-Qur'an and al-Hadith at MI Darut Taqwa Sengonagung Purwosari Pasuruan. . Data collection was carried out through observation, interviews, and documentation to get a complete picture and understanding of the two selected research focuses.
 The results showed (1) the implementation of interactive video learning at MI Darut Taqwa shows that learning using learning methods and media is quite flexible. This means that it is adjusted to the conditions of students. The learning method developed in the Interactive Video media learning is the question and answer method, the discussion method, and the demonstration method. (2) Supporting Factors for the Implementation of Interactive Video Media in Al-Qur'an and Al-Hadith Subjects at MI Darut Taqwa Sengonagung Purwosari Pasuruan Is: interactive video media makes it easy for students to understand lessons, using interactive video media of students' attention and interest very effective. While the inhibiting factor is that in implementing interactive video media the teacher requires time and careful preparation, so it requires a lot of time, too much media if you maximize learning interactive video media in the classroom.

Development of an intelligent grinding system for fabricating aspheric glass lenses

Precision optical systems, such as lithographic projection lens or cameras for satellites, typically composed of glass or ceramics optical components. In the manufacturing processes of glass and ceramics components, grinding is a key technique for curvature generation (CG) of optical surface. However, dimension errors and sub-surface damage (SSD) of components occur during the CG process. High material removal rates during the CG leads to deeper SSD on optical surface. The SSD must be removed by subsequent lapping and polishing processes to ensure high optical surface quality. However, these processes are complex, and a precise process to remove SSD from the aspheric surfaces with tens or hundreds of microns of departure from best fit sphere (BFS) is required. Thus, an efficient precision lens fabrication method can reduce the depth of SSD and help to control the dimension error during the CG process. We developed a five-axis grinding system with intelligent machining techniques to improve the quality of CG process. The intelligent grinding system based on the Tongtai five-axis machine (GT-630) was combined with two measurement modules of the Renishaw measurement probe. A customized computer-aided manufacturing software was developed and applied to this grinding system. Spherical and aspherical components with a maximum diameter of 600 mm can be fabricated using the grinding system. To improve the grinding efficiency, an ultrasonic-assisted module was combined with the BBT 40 tool arbor. The frequency range, amplitude, and power of the ultrasonic device were 15–40 kHz, 0.2–2 μm, and 1000 W, respectively. The intelligent grinding system included several vibration, temperature, and acoustic emission sensors and a microphone to monitor the dynamic status of machine during the grinding process and help to quality control. The wear of the diamond grinding wheel could be predicted immediately by analyzing the collected data in this system. A five-axis machine was applied to an intelligent grinding system for large glass lenses. The fabrication time of 200 mm diameter aspheric lenses reduced about 3 weeks by using this intelligent grinding system to integrate aspherization processes into curvature generation to become an aspheric curvature generation step.

Deep learning based projector defocus compensation in single-pixel imaging.

Fourier single-pixel imaging (FSI) uses a digital projector to illuminate the target with Fourier basis patterns, and captures the back-scattered light with a photodetector to reconstruct a high-quality target image. Like other single-pixel imaging (SPI) schemes, FSI requires the projector to be focused on the target for best performance. In case the projector lens is defocused, the projected patterns are blurred and their interaction with the target produces a low-quality image. To address this problem, we propose a fast, adaptive, and highly-scalable deep learning (DL) approach for projector defocus compensation in FSI. Specifically, we employ a deep convolutional neural network (DCNN), which learns to offset the effects of projector defocusing through training on a large image set reconstructed with varying defocus parameters. The model is further trained on experimental data to make it robust against system bias. Experimental results demonstrate the efficacy of our method in reconstructing high-quality images at high projector defocusing. Comparative results indicate the superiority of our method over conventional FSI and existing projector defocus rectification method. The proposed work can also be extended to other SPI methods influenced by projector defocusing, and open avenues for applying DL to correct optical anomalies in SPI.

Maskless lithography based on oblique scanning of point array with digital distortion correction

The oblique scanning of a rectangular array of ultraviolet (UV) spots provides a feasible means of realizing maskless lithography with well-controlled UV exposure. In such a method, the UV light is modulated by a digital micromirror device (DMD), collected by a microlens/pinhole array, and then projected onto a photoresist (PR) layer for UV patterning. However, the strict requirements imposed on the optical distortion of the image projection system pose a significant technical challenge. Accordingly, the present study proposes a method for improving the UV patterning accuracy by using an empirically-derived distortion model to adjust the working DMD images. The patterning errors caused by optical distortion are then further reduced by adjusting the tilt angle of the oblique scanning process. The experimental results show that the proposed method yields a significant reduction in the UV patterning error. Consequently, it provides a practical solution for performing maskless lithography without the need for a high-quality image projection lens system.

47‐1: The World Smallest OLED Microdisplay Projection Device Design Methodology

We developed the world smallest OLED microdisplay projection device. This device consists of just 2 parts which a high‐brightness Microdisplay based Organic Light Emitting diodes on a silicon backplane panel (M‐OLED) ( 1,000,000 [cd/m2] ) and an optimal lens (F/1.1) for the self‐emitting projection device.This high‐ brightness M‐OLED is used 2 key technologies.The first is a supplying the photoexitation potential to multiple emitting layers in OLED using by the new pixel transistor (Tr.) that can withstand very high voltage in 7.8 pm pixel. The second is the controlling light divergence angle from each self‐emitting pixel that made using micro optical resonance effect from cathode until anode electrode in OLED and the optimized micro lens (ML) for each pixel.Next, we evaluated the relationship between the light divergence angle from M‐OLED and F number (Fno.) of the projection lens and we found parameters and a specific method for controlling the light efficiency of the self‐emitting projection device.Based on the results of these fundamental studies, we established a design methodology for the self‐emitting projection device with high efficiency, and we realized the world smallest self‐emitting projection device (W 10 /D 11 /H 6 (mm)).