Holograms at the Nanoscale: New Imaging for Nature's Tiniest Structures

all right we should probably get started so first of all I would like to welcome all of you and thank you for coming this

is really wonderful that you could actually join us we love to share the kind of interesting work that we do here

and it's really delightful to see that someone of you're interested in this so before I get started I you should know

about the the special security procedures here and I think that that can be probably put up by people in a in

a book in a booth there but it's important that you are aware of where the exits are from this room just in

case if there's an earthquake or and I think like this okay you can see them behind you it's my pleasure to welcome

Tice Gore covered who is our newly minted tunnel ski fellow here it's like

she will tell us about the work that she's doing primarily on the holography and the title of the her talk is about

new imaging of the nature's tiny structures case had learned about

science when she was looking at her broken finger when she was a child growing up at the age of seven and that

of course you know God thinks very interesting biology and physics as well she went on to study physics at

University of Berlin and continued with the graduate studies there and she got a

desert pursues evolve fellowship in Berlin and we slack offered ties

Panofsky fellowship was probably the most prestigious fellowship that we have here and I should mention that ties is

the first woman to have received the Panofsky fellowship here so that's a special honor

without much more ado I just wanted to mention that towards the end of the lecture we'll have plenty of time for

questions we have microphones set up in a room so if you raise your hand I will

recognize you and you can push the button on the little box underneath of

the microphone and that will turn it on but after you're done with your question please turn it off because on the one microphone can be turned on at a time

okay thank you without schnapps Molly do guys well do you hear me yes well thank

you a lot for the introduction and thank you all for coming today if the title

already says I will be talking about Holograms at the nano scales so it might

in my talk I will present you the world first x-ray holograms of viruses

recorded with the most powerful x-ray laser which is located here at SLAC and

my talk is has two parts in the first part I will just talk about holography

what is holography how can we use it to image things I will also show you some

examples which you can basically do at home just to play around with it and all you need is basically a five-dollar

laser pointer and the second part of the talk is mostly focused on what we're

doing here at SLAC such as let's start

what is holography and what are Holograms so you might have a hologram

in your wallet for example on your MasterCard this is the first hologram I

took this source in the back in the University in Berlin this is a reflection holography of coins and

holography is an imaging method which is comparable to photography but it has the

Holograms has much more information in them than regular photos so Dennis Gabor

he was awarded the Nobel Prize for inventing holography he invented the the

holography in 48 and the Nobel Prize it's 71 and holography

is a technique as it says here that enables a light field scatter of objects

to be recorded and later reconstructed and I will just briefly talk about this so if we compare again photography

versus vlog Rafi in photography what you have is you have a film and you scatter

off light of your object and record the

image of the object on on it on a film in holography the basic setup is similar

but there is a very important difference and this is this reference beam so the

reference beam here coming from the side is superimposed with the light

scattering from the object and creates an interference pattern on the film and

this interference pattern contains extra information which we can use for example

to create two 3d images as you will see later on now there are many ways how you

can reconstruct such a hologram so one way is if you just look at the film you

have to shine the reference beam back on the film on the holographic film and you

will see the hologram of your object on the other side of the film so you need

the reference beam for for reconstructing the hologram in this setup now in the for the rest of the

talk I will talk slightly about a different type of reconstruction of Holograms so what we do is we record a

hologram using a camera a CCD camera a camera which you have probably in your smartphone and we connect this camera to

a computer so we don't in order to reconstruct the hologram and retrieve the object we don't have to shine the

reference light on it and we just basically calculate that in a similar

fashion so that we just by pure computation we can retrieve the object

the hologram we record on the CCD chip and this is this types of holograms this

is what I'm going to be talking about for the rest of my talk so what many

don't know is that holography is not only useful to record 3d images

but can be useful also in 2d and even in 1d so here this is this kind of classic

3d holography which everybody knows this is two photos taken from a single

hologram but I'm not different on the different views you angles and what you

see here that when you change your angle you see different projections of the

mouse right so this is that means also that the hologram a single hologram

contains many projections of the mouse this is the contrast to the just simple

photo of a mouse so this is the 3d holographic but the way it was invented

originally by Dennis Gabor was actually as a 2d holography and 2d holography is

very useful if you want to receive high resolution images and he invented it for

electron microscopy in fact and this is one of the folk first Holograms he

recorded so this is the use of 2d Holograms and then some of you may

recognize this experiment this is the famous double slit experiment which you

have to study during every quantum mechanic course and in fact this can

also be regarded as one dimensional holography but I will talk about this later in greater detail just talking

about applications of Holograms so as we mentioned you have Holograms on money

you have Holograms on credit cards Holograms are hard to forge and this is

why they are used for security reasons they can be also used for creating art

just because this one knife then in engineering processes they can be used

to measure stress strain and vibrations and one of my favorite applications is that you can

with hologram with holography you can make basically holographic movies or you

can create you can image ultra-fast processes and one example is actually

listed in gobber's Nobel Prize lecture as shown here so this is two photos

again shown or just taken from a single hologram and this is a hologram of three

flying mosquitoes and so you learn first

thing what you learn is you can create Holograms with really little exposure

times I think here they just use the pulsed laser just the laser pulse so that the the rapidly moving mosquitoes

they appear to freeze and the second thing is of course this mosquitoes they

are randomly oriented in space and you can refocus your hologram and focus on

each mosquito separately just from one exposure so this is the first mosquito

which is slightly in the front and these two mosquitoes are slightly in the back and you can basically process all this

information from a single hologram so this is also a 3d information right so

imagine if if holography would be a superpower and Holloman would be

bothered by mosquitoes during the night he would wake up and within a blink of

an eye he would just create a hologram a 3d hologram of the entire room he would

immediately spot the mosquitoes he would calculate exactly the distances between

the mosquitoes and himself he will focus his powerful laser which he can shoot

from his arm and just evaporate them and just go back to sleep

so this is how amazing holography is okay so what we were talking about right

now is microscopic holography right we these are all Holograms or microscopic

objects but in fact you can use holography to image really small things

so here's just the scale of our world so

we are somewhere here this is the macroscopic scale centimeters meters this is a meter a millimeter here when

you go down this is a human here these are chromosomes our genes animal cells

bacteria then you're at 1 micron and then if you go further down this is the

nano scale and genes viruses 10 to 100 or a few hundred nanometers and then if

you go further down you get to the small molecules and atoms so with optical light what you can do is you can image

or create Holograms of all the structures and I can show you how you can do it using just a

five-dollar laser pointer and nothing else so you might remember that light is a

wave or can be regarded as a wave when it has a certain wavelength and we can use this this character to to image very

small things by a diffraction so this is

just to kind of remind you about what is actually diffraction so if if light

which is here this is the incoming light and it's marked or it's basically here a

plane wave if it if it meets an obstacle or here this is just a one-dimensional slit then it propagates it's a spherical

wave and if you would put a screen behind this slit then what you would see

is just a diverging beam and this is very different from what we know from our macroscopic world right because in

our macroscopic world what you would see on the screen are the sharp edges the shadows of the screen of the slit so for

a very tiny object this is not the case anymore and this is because the light diffracts and light goes here around the corner so

that's pretty amazing now if you make you sit a little bit bigger than the

wavelength of light you can actually in your diffraction pattern you can encode

the size of the slit so what you see here it's a little bit different than

the screen image on the left because what you see here are these dark spots

or these dark modulations in this line pattern and in this dark lines they

carry the structural information of the slit so from from that you can imagine

that diffraction can be quite useful if you want to image things especially very

small things so now diffraction is really odd

diffraction doesn't make a difference between and just the slit or an opaque

obstacle it will create the same diffraction pattern so that's completely counterintuitive for our macroscopic

view because if this would be in macroscopic object you would just see a shadow and so this is a slit and this

can be for example a here and I can just demonstrate you how you can measure your

hair with a laser pointer so

so this is the laser pointer which I have and I just prepared my hair I

didn't want to cut my hair in front of you so maybe you see it now on the

screen on the camera so what you see is

first just a laser spot and when it passes the hair do you see this line pattern so I can again pass this here

now the line pattern is still here and now it's gone again

mine patterns here this vertical line

yeah you see it yeah so and I have to say I

have to be honest with you I have really thin hair this is about 50 microns and

you can see it just with a regular laser pointer in principle you just can Google

how to calculate it from this line pattern you see on the roll okay so so

now we've seen a diffraction pattern of the hair but in fact if you look at the

fraction pattern it's not that you just learn structural information you enter a different space and this is a so-called

reciprocal space and the reciprocal space is a little bit like Alice in

Wonderland of course it marries our reality or our real space but it creates a distortion

of the real space and in the reciprocal space small things appear big and big

things appear small and this enables us to make invisible visible so here for

example I will just show you a couple of very regular things and how they look

like in the reciprocal space

so here again my super laser pointer and

then you see the dot over at the wall and then if I put a netted back which I

stole from my son so it's all high-tech here do you see it right you see this

cross and if you just play around with it it moves it changed orientation okay

so that's fun now what we can do is we

can have a look at a cell phone a smartphone yes so I'm just pointing

laser point a little bit away from you

and now what I'm taking I just I have regular smartphones and I'm reflecting

off the screen towards the screen here and what you see are this dot pattern

maybe I will just turn off the screen

you see that

yeah you see I'm my hand is a bit shaky but you see this dot pattern on this cross and dot pattern and now you can do

the same thing with this CD

that's not exactly okay here you see it

the dot next to the main beam and then you have this ring surrounded so that's

pretty amazing that changes your view of CDs and smartphone sales okay and of

course there's an explanation for for what we see and maybe I forgot the odd

control so what you see is following so

with the netted bag here you see you can resolve the distances in the net here

this is what you've seen on the wall so this really tiny net but I think this is

maybe 500 microns big with a smartphone what you've seen

is a pattern from individual pixels on your smartphone screen and you can go

even smaller so this is the CD and they saw the growth on the CD where the

information is stored and they're one or several micron thin click large small

and you still saw a clear signature just

from from a single laser pointer so this

is the reciprocal space basically with reciprocal space you can you you can use

the diffraction in the reciprocal space to magnify really really small features

let's play around with it a little bit so what happens if you have diffraction

in 2d most of the things I've shown you so far were in 1d but you can also of

course create diffraction pattern and look the representation in the reciprocal space with 2d for example the

pinhole here so what you would see here are ring ring pattern this is here in

false color so you just see the during pattern here the bits of the Ring is

equal even in the highest or even even even if it's far

away from the center of your detector and now if your object or if your

pinhole is we shrink it then your diffraction pattern or and the ring

width gets bigger so again this is the principal small objects they appear

bigger in their reciprocal space and big objects they create this small patterns

okay let's have fun and just look at a few more objects for example here this

is something with many edges so what you would see in your diffraction pattern are the streaks so this is you know okay

there this is something with edges now we can go crazy and just create a

diffraction pattern of the Select logo and this is how it would look like very

confusing and now of course the question is our goal goal was to use the fraction

to image a tiny object and that means usually if you have an experiment you

don't know anything about your object all you get a diffraction pattern and you somehow need to translate it into

the real world and to get a real image and there's a simple mathematical

operation to do this in fact you can download it as an app so for everybody who's interested in this detail please

come after the talk and I can tell you a little bit more about it but let's call it just a translation

algorithm which is just a one-step operation and this is what we do here

this is what we just did and now you see something confusing you don't recognize

your object and the reason is that if you look closely at your object and you

look at the diffraction pattern for example here with slack with a sec logo so the slag logo is very it's a

symmetrical highly a symmetrical but the diffraction pattern seems to be very

symmetrical so it means it has lost some information and once you translate it

back you will see it because the translation will be superposition of all possible orientations and it's

really really hard to guess that this was a slack logo so this is kind of the

drawback of diffraction you can easily access very small scales but it takes

some effort to understand the diffraction pattern okay and of course

this talk is about holography so I will show you how is holography you can

overcome this problem and let's return again into the one dimension just a

fraction form a slit or a hair what you've seen before so this is if you

have just one slit and you have a diffraction pattern this line diffraction pattern which is which has

these modulations on the side to spread like dots and this

tells you about the size of your slit or here or whatever you're imaging now if

you add another slit here you will see a funny thing you will see another

modulation over here diffraction pattern which is kind of indicated here with the arrows and what you record here is the

distance between the slits and this is already very related to Holograms which

I will be talking about later so in the image you don't have only information about the size of your object but the

distance between two objects and this is extremely valuable you can play this game in two dimensions so you remember

the diffraction pattern from a single slit this is usually how it looks like this ring pattern with equal distances

across the detector now if you have two pinholes you will get this straight

modulation right and if you pull them further apart you will get also the straight modulation but there will be

finer and this is again the reason in the reciprocal space things which are

bigger or further apart they appear is a finer feature in the image so this is consistent okay so the next step is

creating a hologram so what you can do is you can just shrink one pinhole and use it as a

reference you remember in holography reference is the most crucial thing you have a reference measurement and what

you're doing with this reference basically you measure the distance between each point in your object and

this is how you create a map of your object so now you recorded the fraction

pattern and you translate it what you get is in the central part that's what

we've seen before this is the superposition of all orientations and then you see the funny things here and

these are the image terms or the cross correlation terms and this are actually carrying the information about this big

object and basically this is nothing else than just the distances between the

reference here and and the object you want to image now we can just

demonstrate it on the slack logo again so with the slack over what we would do we would just add a reference pinhole

which is much smaller than the Select logo it would again record the diffraction pattern and what you would

see is again the superposition of several orientations of flag and then

you would see this image cross terms which actually show you the site logo so

that's nice that only one step operation and you get a unique solution for your problem and this works like microscopes

it should work right they just give you a solution for the structure so that's cool but then now the question is can we

also make a 3d hologram with diffraction on the nano scale and the answer is yes

the only thing you need is again high-tech equipment including again a

laser pointer an aperture and whiteboard

cleaner I will show you this super exciting

sophisticated setup how it works Oh

my mouse is gone so that's good so if I

don't have my mouse I cannot click on the video okay oh here it is so what I'm

doing I'm just closing the aperture and now just spraying the whiteboard cleaner

on the aperture and just watching it with the laser pointer that's it

so that seems extremely boring in the real space but now let's look at the

reciprocal space so I have prepared the setup here let's see if it works

so just screen so that you see what will happen yep yes yes so this is Jessa

that's nothing fancy that's just the laser pointer I have to disappoint you so now I'm just closing the up the

aperture and now I'm just spraying a

little bit of the soap on it and then let's see what happens

you

it's horrible

so I'm just closing the aperture a little bit to kind of show the effect

it's just bubbles moving around but I

think that may be nice to little soap like soap on it

so what you're seeing is now the droplet broke down there's a droplet which is

building up inside the pinhole inside

this droplet there bubbles moving and these bubbles are some of them are smaller than 10 microns and you see

their movement say I think that's good

enough so just kind of clarify what what

you guys are seeing here I took a video because I wasn't even sure this would

work okay

so this is a video of the same process

just in a very very dark room and this is what you see so first I close the

aperture and now I'm spraying the soap and what you see is this very turbulent

motion where I think it's just this big bubbles just floating around

and then at some point there's a droplet building up inside the aperture and you

see the micrometer bubbles floating inside the droplet and I was just

jiggling around the aperture a little bit to kind of induce a little bit more movement you will see it soon so this is

they are moving just by themselves so I'm not going up which is really funny

and then you see this ring pattern here which looks also pretty funny so that's

just triggering them around a little bit and I can tell you that this is a

three-dimensional holographic movie here and I can show you how to read this so

just going back to the details so first we have this 2 micrometer pin pin hole

and then we have this turbulent face where bubbles just form we see it in the

diffraction pattern and then droplet kind of just forms inside the pinholes

and what we see is that there are micrometer small bubbles floating around

and what you see in a single frame of

this video are the so-called mutant rings you see them here and here so this

is a simulation of a Newton ring and the difference to the diffraction pattern just from a single aperture is that the

Newton rings the spacing between the ring patterns it decreases towards the

edges of the detector so this is a new feature and this feature carries

three-dimensional information using pretty simple algorithms what you can do

is you can basically refocus each and individual ring and this will give you a

sharp image of a particle which is floating there in the droplet and when

you do it for every every ring you will

get a three-dimensional map off of your particles floating in in the

droplet so that's very similar to the hologram which I've shown you with the mosquitoes just very small and very fast

and so if we would reconstruct this

single frame what we would get you would get the inside of the droplet and we

would get the positions of the micro bubbles floating around inside the

droplet and if we just recorded frame by frame and recalculated frame by frame we

would get a 3d holographic movie off of the micrometer bubble and so this is

what you can do at home if you're bored

just to explain you how this mutant rings are formed so you might remember

this image of two pinholes which are separated they create this pattern of a

single pinhole with modulation where the distance of the pinholes is recorded the

Straight modulations now if I start to pull the apertures or the spheres apart

along the laser beam access this modulation they become this curvature

and when you go further away basically behind each other then this curvature

will increase and further increase so this is how this Newton rings are formed

and this is why they are carrying 3d information so then let's just sum up so

that just to make sure that now you speak reciprocal what did we learn so

the large object or distances they give us fine modulations if you image

something round like a average every sphere you would get this large round

modulation modulation with equal spacing if you have edges in your object you

will get streaks if you get separated objects which are round you would just

get fine straight modulations and if this objects are also shifted along the

laser axis you will get the Newton so you will get the curvature in this fine modulation so that's good so now

you're good to go to understand x-ray Holograms it's all you need so let's go

to the main topic of this talk which is how to reimage

really small objects and here just to

remind you so the objects we are talking about are not visible with the eye this is viruses senior proteins small

molecules and to image that you need something with a shorter wavelength then

the optical light and the best the best light you can choose for that is x-rays

everybody knows x-rays so as it was

mentioned earlier this was the first image I received in my life the first x-ray image I had a broken finger and so

they took me to the x-ray machine I was like oh my god what happens if they find out that I don't have bones so there was

my biggest fear for some reason it turned out of course I had bones and one

of them was broken so what you see here from this image right is that with

x-rays you can see through things so you get additional information compared to light and as we just discussed earlier

because of the short wavelength and see we can create even you can achieve very

very high resolution down to the atomic scale now they are disadvantages which

come with x-rays unfortunately and one is that they interact with with matter and the reason is that they have a very

different view on the world than we do so if I go to this board here and I

touch it this is very solid I would not have never have the idea that I can walk

through it it's just not happening so if an x-ray sees this board the eastery

says oh there's so much free space right I just can't pass through it because I

can see the distances between the atoms and the lattice so why should I interact

with this matter and that's why in principle x-rays see a

lot more but they also deflect less so you need many extra photons to image

something and then the second disadvantage of course as you all know

x-rays are highly damaging right this is why usually if you get an x-ray image at

the doctor's office they usually try to reduce the exposure time and the reason

is that x-rays is highly ionizing and can destroy basically the structure inside your body so just from that you

can imagine if you want to image really small things really nanoscale things with x-rays what you need are very

intense pulses which are short enough so that you image your example before it's

destructed because otherwise you will just image the damaged particle which

you don't want to and for that we use the most powerful x-ray source in the

world which is LCLs it's also the first hard x-ray laser it's located right here

and this is a bird view from the from the accelerator which is needed to

create this powerful x-ray laser pulses so here electrons are accelerated and in

a way that they emit x-rays which add up and give pulses which are only femtosecond short and just to give you

an example of femtosecond so this is a million of billionth of a second so

imagine if if a second would be the age of the universe a femtosecond would be a

minute so this is how short they are yeah so this is an amazing machine and this allows us to overcome the damage

problem so we be sure that many photons at the sample that the image before the

sample disintegrates and this has been already proven in a couple of pioneering

studies so here just to show you that with x-rays we can access regions which

are not visible with other methods for example the ultra cold so here a couple

of years ago sign discovered that deeply cooled helium droplets superfluid helium droplets they

have this nanoscale tornados tornadoes in them so that's pretty amazing this so

we learn something new about the super cold state of matter and in this

experiment what we did is we heated small nano particles to temperatures which are hotter than the surface of the

Sun and we were just watching them explode so we created an ultra-fast movie and we learned about meta and

extreme conditions superhot matter and of course one super important

application for this is to image fragile nano samples so currently if you want to

receive a high-resolution image of a biological specimen such as a protein on

our virus what you have to do is you have to freeze it and if you freeze it

of course you modify it to some extent if you want to image them at room

temperature in the native environment then x-ray lasers are the way to go so here's a set up which was realized about

now it's six years ago so here viruses were injected single viruses

were injected into the FEL focus and the diffraction pattern from the viruses

were recorded for further downstream and this is the result of this pioneering

study so there we the image mini viruses

and mini viruses we have this equal cylindrical shape so this was the object

more or less this was a diffraction pattern and their reconstruction well it

had three solutions and why is that you remember if you just deflect from an object alone and extremely hard to get

the structure back because you would a lot or you lose a lot of information so it took some thousands of steps and pre

assumptions which led to three different solutions so this is like when you image

something and you with the microscope and you microscope spits out three solutions for the structure you're

imaging so that's that's really good but not the optimal case for

determining the structure of your specimen right now as we talked before

you can use holography to overcome this problem and holography x-ray holography

has been done here at srl many years ago on magnetic films but the problem with

x-ray holography state-of-art extra holography is that the reference scatterer needs to be placed in the mask

very carefully nano manufactured and it's not really easily to be combined

with just randomly injected samples such as the bio samples so people were

thinking and about combining both methods for years until we tried this

where we decided okay we cannot really place a mask but we can place reference

galleries which are also randomly injected into the fal focus so here are seen on little scene on crystals and we

just injected them with a sample we overlapped the sample beams and so that there were many events when they were

close enough to record a hologram and it was a setup so we had the bio injector from the top the Exene on eyes injectors

from the side and we overlapped them in a way that each time the FAL came and

illuminated both the diffraction pattern or there was a high chance the diffraction pattern would turn out to be

a hologram and we were successful so just as a comparison here this is the pioneering

study without holography with three solutions and thousands of sets in between and this is what we did on the

same sample on the same virus so here with holography what you see is you get

clearly this equals a total shape of the hollow of the of the virus and this is a

unique solution so this is like a real microscope and here you have thousands of steps this is only one step so this

is the major outcome of our experiment but then we also imaged smaller viruses

so we could reconstruct them and then we looked closer at the Holograms

and for you guys it will be really easy to Chris now you speak reciprocal right we already really so much about it so if

you look very closely at the hologram but the Holograms you can discover that this much more than the structure of the

virus so let's just look for the features we've learned so far right so

we learn features from from a small sphere or from an aperture right round

features this is what we see here here is the ring here's the ring and here's also ring

which you don't see unfortunately but it still is it's pretty you see this modulation so there's one sphere okay

that's good then we see streaks we know the streaks there must be edges right

and we know this is a virus so this was probably the virus what we see more if

we zoom in to this part if we zoom in really closely then we will discover this fine modulations right you see them

here and then this modulation so some art straight and some are curved so that

means that some particles were very close to each other and in the plane perpendicular to the to the laser and

some were torn apart so that also means that probably there are more than two particles in the hologram so most likely

there is please one sphere at least one virus and then something else which is

which is separated along along the fal axis now if you just translate the

diffraction side and the way we used to do it all the times before this is exactly what we get so our guess was

right so we really speak reciprocal by now so what you get is you get this

super-important super-important term and

then you have this three image terms and they're twin images this is just a

feature so you can disregard this so that's clearly we have three particles in there and apparently we had one

chignon particle which was larger than the other so to see non particles and

then the virus okay and we know that the exciton particles acted as references it

means that just reading the distances here in the translation from the diffraction we know the distances

between the virus and and in the clusters or the spheres 1616 on spheres

and now we can go three dimensional so what you can do is you just refocus your

hologram and that means you will just scan along the along the laser path and

this is how it looks like so you will see that some features become sharp right and others appear to be auto focus

now this is this becomes more pronounced now this becomes more pronounced and

every time a feature gets trapped you know there is a particles there so if you just kind of add up the frames right

so this is these are the image terms and you basically just walk across the focus

and you just look when the features become pronounced and sharp and then you

know this is where your particle was located and that means we created a three-dimensional hologram from a single

exposure which I think has not been done

so far with nano scale particles so just to emphasize it so this nano particles

they were moving with it close to the speed of sound and they were just

randomly injected we had did not have any knowledge about them but using holography we were able to record a full

3d map between them so this is this was

a major outcome of this experiment and there are many potential applications I

would just highlight a few of them so especially processes which happen in gas

phase on moving particles such as everything which is happening in our atmosphere so if you want to know how

clouds are formed how air pollution is formed this all involves nano particle

nucleation dynamics and until now this has been studied only from indirect signal now we can directly

image it and we hope that it might help to understand how air pollution is created to create better climate models

and better understand climate change another field of application is

catalysis where basically nanoparticles are used to accelerate chemical

processes and this is important for energy harvesting so for example to

create more efficient batteries in the future and another field is for example

nano plasmonics this is a relatively new field where nanoparticles are illuminated with optical lights and

there are some funny effects which for example lead to the fact that if you

cover a solar panel with nanoparticles then the the harvest the energy harvest

increases and the processes which happen here on the nano scale and also

sometimes from the femtosecond scale so this is we can image them directly and make movies of this processes and then I

think the most long-term application what we would like to go is to really image Brix of life and really to get

information of individual proteins or or

us about bio particles like viruses because you might know not know this but

most of our knowledge about nano scale objects especially bio object is from

measurements on many many objects and averaging over them so this is the same

approach as if I would say ok I don't know humans and I will just take all the humans in this room and I will image

each of you from a different angle then I would average over this photos and then I would create an average human so

what you would get probably is a supermodel and you will learn a lot

about humans from the supermodel because we have many similarities but you might have noticed that we are all so

different so and you will learn little about that and as many biological systems also

proteins and in viruses they are different and right now most of the knowledge structural knowledge we have

from them is from such averaging right and with x-ray Fe else we are going

towards this possibility that we will be able to see single bio particles from a

single exposure and this is the end of my talk I just like to thank a couple of

people here you see this was a big collaboration so it's really hard to get

beam time at LCLs so once we get beam time it's not uncommon that that

scientists would team up as in this case and there are many people who I have to

say who greatly contributed to this work I would point out two of them Natalia

mer he is a PhD student in Berlin who helped a lot and understanding the Holograms recorded and then Christopher

oh who bots my supervisor when I came to slag and when I realized this

project and my special thanks goes also to the people who helped me prepare this

public lecture especially my son who helped me to work on the demos he was my

main source and I had in the baggages so thank you and of course thank you to all of you

for your attention and being here thanks

thank you very much dice for a wonderful talk so we have time for a few questions as I mentioned earlier if you have a

question please raise your hand and I will recognize you and you then push the red button on your on your microphone

okay so go ahead so maybe I can start with you what you mentioned about

applications to technique but what how would you what improvements to the technique would you are you looking at

how would you have how does this how will this technique get better so what we need to work on is the resolution so

currently our resolution is somewhere between 10 to 30 nanometers so in order

to be to the state of arts imaging systems for example bio nanoparticles

which is currently the cryo-em cryo-electron microscopy we need to increase at least an order of magnitude

and in resolution even even more so but again so what they do is again is this

averaging over the sample so they did they also they do have the image

processing and they averaged about around many symbols and they also take some pre assumptions and this is how

they get the high resolution images so this is this is basically what we're

working on we're also working on the resolution and 3d which we try to do and

as a laser in Hamburg in a free electron laser in Hamburg we did not succeed

unfortunately because of a filter in front are installed in front of the detector but we solved another problem

which is as you can imagine if you would just intersect particle beams then you

hit create when they are exactly in the same spot so the the fal focus is only

one micrometer small it's pretty low so we had really low hit rates but now we

learn how we can inject references right from the source where the bio particles

come came from and it seems that we increase the hit rate by three two orders of magnitude

right more questions yeah go ahead

you mentioned the difficulty with reconstructing the image then none and

the unambiguous reconstruction basically will be possible to use two or three

reference beams to resolve ambiguities yes this is basically what we did right

we had to reference clusters and we just selected the best the best reference or the best image but yet it's a very good

question so you can so you can for example improve your signal or your contrast by including more and more

references it says this is a very good idea we already we also tried that but

we still haven't looked at the data but yeah this is also one thing we've tried yes I think there's a question in the

back there can you use interference wave

can you use interference wave to render an object invisible to check the

invisible render objects invisible oh that's a great question I don't know

have you thought about it whoo that's a really good question our it is this

going to lead some day to personalized medicine where you can look at someone's

cancer cells and identify them and yeah

I mean this is kind of exactly this is what I was talking about as a as a kind

of long-term goal however I have to admit that this x-ray lasers are

extremely expensive and they are very long so I so with x-ray lasers the state

of art actually has we kind of make more proof of principle concepts and we can look at individual kind of structures we

want to resolve but it's way too expensive to take a person's going to a sample from a person and then

put it in and look at it so if if if they seek knowledge yes now if if x-ray

lasers can be shrunk just to a smaller

space and will become cheaper yes why not we hope use the sphere of xenon element

I'm all atoms as a referent is that choice because they're well understood

or their packing is particularly well in stood what what about xenon made that an attractive reference so the honest

answer is so it's because I my PhD

project was on casino clusters and I just had a lot of experimental

experience with that and I knew that they produce very bright a diffraction pattern that which is essential for

reference wave and they are almost spherical so this is a well-known fact and we tested them and every else and

then I just thought well we know the system very well we know how to control it let's just try to use it for

something else but yeah this it's a very good question so it's kind of 16 are we

use xenon because it's a formed Spears very easily and we know how to control them and because they have many

electrons and scatter a lot so that's the historical reasons were in the first place my supervisor chose that it's a

sample but I just kind of took it over to use it for holography sorry

microphone awkward thank you there we go

sorry does this technique scale to other wavelengths like millimeter wave true

yes I mean holography supplies on radio frequency and astronomy or light on so

I've recently you a read an article that you can use whyphy like the white mute

or you have at home you can basically if this somebody you with an antenna outside your home they can create a 3d image of what's

inside your home it is so holography all

right so you make um 3d holographic

presentation you also fire a lot of doses I don't know how far they are

space and time so could you make a movie by measure signals for pulses yes well after the

other so yes actually you get biological reactions yes over time yes this is one

of the main goals so basically the central second time scale allows you basically to enter the first steps of a

chemical reaction and this is what we are trying to do so they are very

promising experiments on molecule ensembles so we cannot image single

molecules right now but if you image an ensemble and then we excite the molecules you can see the changes in the

diffraction pattern my question is a

kind of episome illogical one but hi

it's like Galileo Galilei look into the Stars and the discovering things this is

the kind of technology advancement and what comes what that kind of result you

will look into the face of the god but say no look into that then what comes

with that it's it's really still thinking about the bacteria that time do

you look at the image then we may come up with some kind of answer but this

will result some kind of answer it's a question I have you and your colleagues

your teachers what do they think about this looking into peeping into unknown

going to be solve something so this is a

very deep question and such good questions are always hard

to answer however this is a very basic question about all science right why do we do basic science yeah

and in many cases basic science in the firt is the first glance it appears to

be not useful but then 20 or 30 years later it just turns out that this is

actually something interesting so inherently it's just if you if you if

you are in basic science sometimes it's very hard to judge what will be interesting right so when people started

looking at simsimi conductors which are essential for computers their significance was not recognized

immediately holography took almost 30 years to become significant so you just

imagined god were invented in 48 right after the world war ii he was thinking

about how to increase the resolution of electron microscopy I think this was crazy like if I could be at 49 this is

what what I would be thinking about probably but this is what he did and at the time he did not have the tools to

realize what he was aiming for and there were much more limitations for electron microscopy so this was kind of boring

and his work rested until the invention of the laser and then application basically exploded so it's always good

to ask yourself what why are you doing what you're doing right but all I'm saying is that sometimes with basic

science you don't get a straightforward answer and it's a scientist I'm basically driven by curiosity I was

enjoying a lot working on this presentation for example on the demo with it with a solution you can imagine

my act like this was an act of desperation because I thought I need to show Newton links to the audience so

that they see it that they can kind of play around with them and in a versus in my office how like watch what can it

what can I take right so this is um you know kind of nonsense but fun I I assume

that this is all with with current LCLs the final kilometer

how will your work be helped with LCLs - and and what's our timetable to roll

that out yes so what we're thinking for LCLs - is that we will try to image

ultra-fast processes and particularly what we want is we want to use the high

repetition of LCLs - so that we for example if you want to image how

plasmons so for nano plasmonic application how how matter behaves when

it's kind of excited by light and then

the electrons move and inside the nano particles so we hope to is to develop first an injection technique which is

good for nanophotonics devices for example and the second thing is we will use the high repetition rate because

then we have much more single shots which we can form to a movie and we need

less time to record a movie so this is with this technique this is one of the applications for example yes so I think

it's 2020 19 yeah I think it's 1920 yeah but it's very much approved in it it's

moving forward at this point all right

if there are number of questions that's thank iodized again [Applause]

[Music]

SLAC National Accelerator Laboratory