Path: ...!feeds.phibee-telecom.net!3.eu.feeder.erje.net!feeder.erje.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: A better electron microscope
Date: Mon, 12 Aug 2024 15:42:09 +1000
Organization: A noiseless patient Spider
Lines: 73
Message-ID: <v9c7bh$35am4$1@dont-email.me>
References: <v8uv50$sle1$1@solani.org> <v8v7pk$29iuv$1@dont-email.me>
 <v9aj2r$262s3$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Injection-Date: Mon, 12 Aug 2024 07:42:11 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="530a6d505246b03592499e2ca7642253";
	logging-data="3320516"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1/ODGju2mB5d7O0JzPsOygNkUMKiH2T0Tk="
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:ZfKCS00zxNPSlxIcHyxjK9GQin4=
X-Antivirus: Norton (VPS 240811-12, 12/8/2024), Outbound message
In-Reply-To: <v9aj2r$262s3$1@dont-email.me>
Content-Language: en-US
X-Antivirus-Status: Clean
Bytes: 4194

On 12/08/2024 12:50 am, John R Walliker wrote:
> On 07/08/2024 08:29, Bill Sloman wrote:
>> On 7/08/2024 3:02 pm, Jan Panteltje wrote:
>>> Scientists revolutionize microscopy by reimagining the logic of imaging
>>>   https://www.sciencedaily.com/releases/2024/08/240801142229.htm
>>>
>>> New method significantly reduces the time and damaging radiation used 
>>> to image fragile specimens
>>> Date:
>>>    August 2, 2024
>>> Source:
>>>   Trinity College Dublin
>>> Summary:
>>>   Scientists have devised an innovative imaging method using 
>>> state-of-the-art microscopes
>>>   that significantly reduces the time and radiation required.
>>>   Their work represents a significant breakthrough that will benefit 
>>> several disciplines,
>>>   from materials science to medicine, as the method promises to 
>>> deliver improved
>>>   imaging for sensitive materials such as biological tissues that are 
>>> especially
>>>   vulnerable to damage.
>>>
>>> And chips?
>>
>> The paper claims "Giving microscopists the ability to 'blank' or 
>> 'shutter' the electron beam on and off in a matter of nanoseconds in 
>> response to real-time events has never been done before."
>>
>> It isn't true. The stroboscopic electron microscopes that Cambridge 
>> Instruments sold from about 1983 as electron beam testers could 
>> deliver a half-nanosecond wide pulse of electrons.
>>
>> The electron beam microfabrictors we'd been selling for year could 
>> turn the beam on and off in less than 10nsec - I worked on the 
>> beam-blankers for both.
>>
>> Scanning transmission microscopes do use higher voltage electrons, but 
>> that just means that the electrodes that blank the beam have to be 
>> longer. With a half nanosecond wide pulse, you couldn't make the 
>> plates too long for 2kV electrons because the transit time got longer 
>> than the blanking period and I had to invent a solution to get around 
>> that, but "a matter of nanoseconds" give you more wiggle-room.
>>
> A bigger problem for biological tissues is that they have to be dried
> before they can be put in a vacuum chamber and this process can distort
> them.  They also usually need to be stained with a heavy element such
> as uranium for TEM and coated with gold or other conductive materials
> for SEM.

There are "environmental SEMs" that work by differential pumping and can 
allow enough water vapour around a cold specimen to stop it dehydrating 
but not enough to scatter too many of the imaging electrons.

Their commercial success came after my time on electron-microscopes, so 
I don't know much about them. My boss from Cambridge Instruments moved 
on to FEI so he knew more, and had talked about them, but he died around 
2010.

https://en.wikipedia.org/wiki/Environmental_scanning_electron_microscope

-- 
Bill Sloman, Sydney






-- 
This email has been checked for viruses by Norton antivirus software.
www.norton.com