Laser spot size and scaling laws for laser beam additive manufacturing

Abstract The constant size reduction of the elementary structures in integrated circuits (ICs) and their increasing complexity pushes laser probing techniques to their limits. For old technologies these techniques were powerful tools in defects detection and internal analysis, but now the major limitations of the laser spot size implies the understanding of the complex information contained in the reflected beam when it covers an area of multiple elementary structures. Knowing the contribution of each elementary structure covered by the laser spot in the reflected laser beam is the key to have a good analysis and interpretation of the probed area. In this paper we will expose the different parameters that modify the intensity of a laser beam and the contribution of a basic structure covered by a big laser spot size as well as the systematic approach we have built to deal with this challenging reflected laser probe signal from multiple elementary substructures in very deep submicron technologies.

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Relativistic Gaussian laser beam self-focusing in collisional quantum plasmas

Laser and Particle Beams ◽

10.1017/s0263034615000063 ◽

2015 ◽

Vol 33 (3) ◽

pp. 397-403 ◽

Cited By ~ 7

Author(s):

S. Zare ◽

S. Rezaee ◽

E. Yazdani ◽

A. Anvari ◽

R. Sadighi-Bonabi

Keyword(s):

Laser Beam ◽

Laser Energy ◽

Oscillation Amplitude ◽

Beam Width ◽

Spot Size ◽

Collisional Plasma ◽

Laser Spot ◽

Quantum Plasma ◽

Laser Spot Size ◽

Self Focusing

AbstractPropagation of Gaussian X-ray laser beam is presented in collisional quantum plasma and the beam width oscillation is studied along the propagation direction. It is noticed that due to energy absorption in collisional plasma, the laser energy drops to an amount less than the critical value of the self-focusing effect and consequently, the laser beam defocuses. It is found that the oscillation amplitude of the laser spot size enhances while passing through collisional plasma. For the greater values of collision frequency, the beam width oscillates with higher amplitude and defocuses in a shallower plasma depth. Also, it is realized that in a dense plasma environment, the laser self-focusing occurs earlier with the higher oscillation amplitude, smaller laser spot size and more oscillations.

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Modelling of the laser spot size dependence of retinal thermal damage

International Laser Safety Conference ◽

10.2351/1.5056610 ◽

2005 ◽

Cited By ~ 1

Author(s):

Karl Schulmeister ◽

Bernhard Seiser ◽

Florian Edthofer ◽

David J. Lund

Keyword(s):

Size Dependence ◽

Thermal Damage ◽

Spot Size ◽

Laser Spot ◽

Laser Spot Size

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Long lifetime of bialkali photocathodes operating in high gradient superconducting radio frequency gun

Scientific Reports ◽

10.1038/s41598-021-83997-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

E. Wang ◽

V. N. Litvinenko ◽

I. Pinayev ◽

M. Gaowei ◽

J. Skaritka ◽

...

Keyword(s):

Radio Frequency ◽

Electron Beams ◽

Spot Size ◽

Laser Spot ◽

Laser Spot Size ◽

High Quantum Efficiency ◽

High Brightness ◽

High Charge ◽

Superconducting Radio Frequency ◽

Long Lifetime

AbstractHigh brightness, high charge electron beams are critical for a number of advanced accelerator applications. The initial emittance of the electron beam, which is determined by the mean transverse energy (MTE) and laser spot size, is one of the most important parameters determining the beam quality. The bialkali photocathodes illuminated by a visible laser have the advantages of high quantum efficiency (QE) and low MTE. Furthermore, Superconducting Radio Frequency (SRF) guns can operate in the continuous wave (CW) mode at high accelerating gradients, e.g. with significant reduction of the laser spot size at the photocathode. Combining the bialkali photocathode with the SRF gun enables generation of high charge, high brightness, and possibly high average current electron beams. However, integrating the high QE semiconductor photocathode into the SRF guns has been challenging. In this article, we report on the development of bialkali photocathodes for successful operation in the SRF gun with months-long lifetime while delivering CW beams with nano-coulomb charge per bunch. This achievement opens a new era for high charge, high brightness CW electron beams.

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