Comments on: Power series https://habitablezone.com/2021/01/27/power-series/ Mon, 06 Apr 2026 12:03:37 -0700 hourly 1 http://wordpress.org/?v=3.3.1 By: DanS https://habitablezone.com/2021/01/27/power-series/#comment-46626 DanS Mon, 01 Feb 2021 21:50:35 +0000 https://habitablezone.com/?p=87431#comment-46626 Yes, dangers the general public are untrained for, cannot possibly see and yet are very, very real. (N/T) Yes, dangers the general public are untrained for, cannot possibly see and yet are very, very real. (N/T)

]]> By: RL https://habitablezone.com/2021/01/27/power-series/#comment-46621 RL Sat, 30 Jan 2021 22:20:47 +0000 https://habitablezone.com/?p=87431#comment-46621 I was put in charge of switching out the 40 W laser used by the Extreme UltraViolet Lithography Project and replacing it with a monstrous 1500 W laser system- 3 beams, each 500W. The wavelength was 1064nm, so completely invisible to the human eye, but the eye could still focus it on the retina. Your first warning would be an audible 'pop' as a section of your retina vaporized and then your eyeball would fill with blood. In addition to warning signs, audible alarms and flashing warning lights I took a pair of broken laser goggles and placed them in the beam for a second and hung the resulting mess on the door to enter the lab- it was an effective warning. 1 second of exposure was enough blow a hole through the goggles. I also posted a first hand account from someone that had eye damage from a similar less powerful laser- it included the line "It was like looking at the world through a fishbowl filled with glycerin, blood and black pepper flakes" :) People took laser safety pretty seriously when they came through that door. That laser scared the crap out of me... part of the alignment process was using a flashlight to look for smoke from stray light hitting something it shouldn't... I was put in charge of switching out the 40 W laser used by the Extreme UltraViolet Lithography Project and replacing it with a monstrous 1500 W laser system- 3 beams, each 500W. The wavelength was 1064nm, so completely invisible to the human eye, but the eye could still focus it on the retina. Your first warning would be an audible ‘pop’ as a section of your retina vaporized and then your eyeball would fill with blood.

In addition to warning signs, audible alarms and flashing warning lights I took a pair of broken laser goggles and placed them in the beam for a second and hung the resulting mess on the door to enter the lab- it was an effective warning. 1 second of exposure was enough blow a hole through the goggles. I also posted a first hand account from someone that had eye damage from a similar less powerful laser- it included the line “It was like looking at the world through a fishbowl filled with glycerin, blood and black pepper flakes”

:) People took laser safety pretty seriously when they came through that door.

That laser scared the crap out of me… part of the alignment process was using a flashlight to look for smoke from stray light hitting something it shouldn’t…

]]> By: DanS https://habitablezone.com/2021/01/27/power-series/#comment-46619 DanS Sat, 30 Jan 2021 19:37:12 +0000 https://habitablezone.com/?p=87431#comment-46619 I was standing at my station, working (crappy warehouse job) and a genuine engineer walked by. We had been friends for quite some time. On this particular occasion, he was carrying his laptop to a pallet for inventory work. Dangling over his arm was his laser mouse, which flashed across my eyes. Very powerful glare -- from the mouse. I was standing at my station, working (crappy warehouse job) and a genuine engineer walked by. We had been friends for quite some time. On this particular occasion, he was carrying his laptop to a pallet for inventory work. Dangling over his arm was his laser mouse, which flashed across my eyes.

Very powerful glare — from the mouse.

]]> By: RL https://habitablezone.com/2021/01/27/power-series/#comment-46611 RL Fri, 29 Jan 2021 02:14:40 +0000 https://habitablezone.com/?p=87431#comment-46611 The use of ultrashort pulse lasers has grown rapidly over the years, with more uses being discovered all the time- the ability to deliver high power, low energy pulses to a material for an exceedingly brief period of time allows you to do things not possible before. If you use a continuous laser beam (not a pulsed one) to drill a hole in metal, or to cut metal you will get a mess. In addition to the material you want to remove, the energy of the laser will also heat and melt the surrounding metal. Ultra-short pulses, in contrast, deliver their energy to the material so fast that there is no time for the bulk material to be heated. In the 10^-13 seconds it takes for the pulse to deliver is energy, the atoms at the focus are effectively standing still. Their thermal vibration is slow on this time scale. On the timescale of the atoms thermal motion they see their electrons ripped away nearly instantaneously, and then densely packed positive ions undergo Coulomb explosion before they even have a chance to transmit their thermal energy to the surrounding material. <img src="https://www.assemblymag.com/ext/resources/Issues/2015/October/asb1015med1.jpg?1443718095" alt="" width="600" /> Here is a hole drilled with a long-pulse (nano-second) laser (left) and a femtosecond laser (right): <img src="https://img.laserfocusworld.com/files/base/ebm/lfw/image/2016/01/th_0706lfw_03f1.png?auto=format&dpr=2&w=720" alt="" width="600" /> This 'cool' method of laser machining allows extremely clean micro-machining of materials with exquisite detail on the micron scale. <img src="https://futaku.co.jp/wp2015/wp-content/uploads/t10_05.jpg" alt="" /> The absence of heating of surrounding material has also made ultra-short pulse lasers an extremely valuable tool in delicate surgical procedures such as eye surgery. Femtosecond lasers can also be used to 3-d print objects with sub-micron resolution: <img src="https://images.squarespace-cdn.com/content/v1/564365e9e4b0c236a24b0ecd/1556549265054-NFMYS1XUR1USYX9GH2XM/ke17ZwdGBToddI8pDm48kCj9c3TcsyqK5HqlXzVMJuRZw-zPPgdn4jUwVcJE1ZvWQUxwkmyExglNqGp0IvTJZamWLI2zvYWH8K3-s_4yszcp2ryTI0HqTOaaUohrI8PIWgh2duSymrJ2c-XDmVpcOE1U_S7pcrHnkY7uf34t9B8KMshLAGzx4R3EDFOm1kBS/h.jpg?format=1500w" alt="" /> The use of ultrashort pulse lasers has grown rapidly over the years, with more uses being discovered all the time- the ability to deliver high power, low energy pulses to a material for an exceedingly brief period of time allows you to do things not possible before.

If you use a continuous laser beam (not a pulsed one) to drill a hole in metal, or to cut metal you will get a mess. In addition to the material you want to remove, the energy of the laser will also heat and melt the surrounding metal. Ultra-short pulses, in contrast, deliver their energy to the material so fast that there is no time for the bulk material to be heated. In the 10^-13 seconds it takes for the pulse to deliver is energy, the atoms at the focus are effectively standing still. Their thermal vibration is slow on this time scale.

On the timescale of the atoms thermal motion they see their electrons ripped away nearly instantaneously, and then densely packed positive ions undergo Coulomb explosion before they even have a chance to transmit their thermal energy to the surrounding material.

Here is a hole drilled with a long-pulse (nano-second) laser (left) and a femtosecond laser (right):

This ‘cool’ method of laser machining allows extremely clean micro-machining of materials with exquisite detail on the micron scale.

The absence of heating of surrounding material has also made ultra-short pulse lasers an extremely valuable tool in delicate surgical procedures such as eye surgery.

Femtosecond lasers can also be used to 3-d print objects with sub-micron resolution:

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