Part 2 of this article continued the exploration of the basic optical tweezer. This part builds up to a complete system, DIY optical tweezer systems, and extensions to the basic optical-tweezer arrangement. The optical tweezer is obviously not a simple system, and a complete system requires lenses, dichroic mirrors, a laser, video camera, isolation against […]
Optical tweezers move nano-objects, Part 2: The optical path
A combination of optics, lasers, electronics, and combined with advanced physics principles, allows “touch-free” physical manipulation of molecules, viruses, and other nano-sized objects. Part 1 of this article presented the goals of the optical-tweezer design and some of the reasoning which leads to it. This part continues to build up to a larger, complete system. […]
Optical tweezers move nano-objects, Part 1: The Principles
A combination of optics, lasers, electronics, and combined with advanced physics principles, allows “touch-free” physical manipulation of molecules, viruses, and other nano-sized objects. How do you manipulate and move tiny objects such as pieces of DNA or living cells? Conventional mechanical or vacuum tweezers, no matter how small, couldn’t grab them and would cause damage […]
The RF power amplifier, Part 1: Functions
In the RF signal chain, the power amplifier (PA) is the active element located between the transmitter signal chain circuitry and the antenna, Figure 1. It is often a single discrete component, one with requirements and parameters which differ from those of much of the transmit chain as well as the receiver circuitry. This FAQ […]
RF/Microwave bandpass filter implementations, Part 3: Microstrip, coaxial, and helical filters
Part 2 looked at two types of RF/microwave filters, but there are many more, including ceramic coaxial filters and helical filters. They are discussed in this part. Microstrip filters Microstrip filters are built as a carefully defined pattern on a PC board. There is almost no limit to the filter designs which can be built […]
RF/Microwave bandpass filter implementations, Part 2: Cavity and comb filters
The well-known and extensively analyzed lumped-element bandpass filter is generally not suitable for the RF/microwave region, but there are many distributed-element, energy-based alternatives. Part 1 of this article established the context for these RF/microwave filters, which operate in the spectrum from several hundred MHz and higher, and increasingly cannot use discrete lumped-circuit elements (RLCs). Instead, […]
RF/Microwave bandpass filter implementations, Part 1: Distributed filters
The well-known and extensively analyzed lumped-element bandpass filter is generally not suitable for the RF/microwave region, but there are many distributed-element, energy-based alternatives. Just say the word “filters,” and for many engineers, the mention of this topic stirs a mix of feelings ranging from fear to relief. Why fear? Because filters as a topic in […]
Lasers, optics, electronics and more yield terahertz sources, Part 4 – Laughing gas
The terahertz part of the electromagnetic spectrum between millimeter waves and optical range remains a largely untapped, difficult-to-use resource; researchers are investigating different techniques for efficiently generating terahertz waves to promote the use of this part of the spectrum. Approach #3: Laughing Gas A team at MIT in close collaboration with one at nearby […]
Lasers, optics, electronics and more yield terahertz sources, Part 3 – Infrared lasers and plasma
The terahertz part of the electromagnetic spectrum between millimeter waves and optical range remains a largely untapped, difficult-to-use resource; researchers are investigating different techniques for efficiently generating terahertz waves to promote use of this part of the spectrum. Approach #2: Infrared Lasers and Plasma A research group based at TU Wein (Vienna University of Technology), […]
Lasers, optics, electronics and more yield terahertz sources, Part 2 – Lasers and acoustics
The terahertz part of the electromagnetic spectrum between millimeter waves and optical range remains a largely untapped, difficult-to-use resource; researchers are investigating different techniques for efficiently generating terahertz waves to promote the use of this part of the spectrum. Approach #1: Lasers and Acoustic Modulation A recent project and paper by a collaborative team from […]
