Reactive Atom Plasma (RAP) figuring machine for meter class optical surfaces

A new surface figuring machine called Helios 1200 is presented in this paper. It is designed for the figuring of meter sized optical surfaces with form accuracy correction capability better than 20 nm rms within a reduced number of iterations. Unlike other large figuring facilities using energy beams, Helios 1200 operates a plasma torch at atmospheric pressure, offers a high material removal rate, and a relatively low running cost. This facility is ideal to process large optical components, lightweight optics, silicon based and difficult to machine materials, aspheric, and free form surfaces. Also, the surfaces processed by the reactive atom plasma (RAP) are easy to fine polish through hand conventional sub-aperture polishing techniques. These unique combined features lead to a new capability for the fabrication of optical components opening up novel design possibilities for optical engineers. The key technical features of this large RAP machine are fast figuring capabilities, non-contact material removal tool, the use of a near Gaussian footprint energy beam, and a proven tool path strategy for the management of the heat transfer. Helios 1200 complies with the European machine safety standard and can be used with different types of reactive gases using either fluorine or chlorine compounds. In this paper, first the need for large optical component is discussed. Then, the RAP facility is described: radio frequency R.F generator, plasma torch, and 3 axis computer numerically controlled motion system. Both the machine design and the performance of the RAP tool is assessed under specific production conditions and in the context of meter class mirror and lens fabrication

Yield improvement using configurable analogue transistors (CATs)

Continued process scaling has led to significant yield and reliability challenges for today’s designers. Analogue circuits are particularly susceptible to poor variation, driving the need for new yield resilient techniques in this area. This paper describes a new configurable analogue transistor structure and supporting methodology that facilitates variation compensation at the post-manufacture stage. The approach has demonstrated significant yield improvements and can be applied to any analogue circui

Influence of parasitic capacitance variations on 65 nm and 32 nm predictive technology model SRAM core-cells

The continuous improving of CMOS technology allows the realization of digital circuits and in particular static random access memories that, compared with previous technologies, contain an impressive number of transistors. The use of new production processes introduces a set of parasitic effects that gain more and more importance with the scaling down of the technology. In particular, even small variations of parasitic capacitances in CMOS devices are expected to become an additional source of faulty behaviors in future technologies. This paper analyzes and compares the effect of parasitic capacitance variations in a SRAM memory circuit realized with 65 nm and 32 nm predictive technology model

Design of ultraprecision machine tools with application to manufacturing of miniature and micro components

Currently the underlying necessities for predictability, producibility and productivity remain big issues in ultraprecision machining of miniature/microproducts. The demand on rapid and economic fabrication of miniature/microproducts with complex shapes has also made new challenges for ultraprecision machine tool design. In this paper the design for an ultraprecision machine tool is introduced by describing its key machine elements and machine tool design procedures. The focus is on the review and assessment of the state-of-the-art ultraprecision machining tools. It also illustrates the application promise of miniature/microproducts. The trends on machine tool development, tooling, workpiece material and machining processes are pointed out

Adaptive differential amplitude pulse-position modulation technique (DAPPM) using fuzzy logic for optical wireless communication channels

In the past few years, people have become increasingly demanding for high transmission rate, using high-speed data transfer rate, the number of user increased every year, therefore the high-speed optical wireless communication link have become more popular. Optical wireless communication has the potential for extremely high data rates of up to tens of Gigabits per second (Gb/s). An optical wireless channel is usually a non-directed link which can be categorized as either line-of-sight (LOS) or diffuses. Modulation techniques have attracted increasing attention in optical wireless communication, therefore in this project; a hybrid modulation technique named Differential Amplitude Pulse-Position Modulation (DAPPM) is proposed to improve the channel immunity by utilizing optimized modulation to channel. The average symbol length, unit transmission rate, channel capacity, peak-to-average power ratio (PAPR), transmission capacity, bandwidth requirement and power requirement of the DAPPM were determined and compared with other modulation schemes such as On-Off Key (OOK), Pulse-Amplitude Modulation (PAM), Pulse-Position Modulation (PPM), Differential Pulse-Position Modulation (DPPM), and Multilevel Digital Pulse Interval Modulation (MDPIM). Simulation result shows that DAPPM gives better bandwidth and power efficiency depending on the number of amplitude level (A) and the maximum length (L) of a symbol. In addition, the fuzzy logic module is developed to assist the adaptation process of differential amplitude pulse-position modulation. Mamdani fuzzy logic method is used in which the decisions made by the system will be approaching to what would be decided by the user in the real world