•Thin film coating
•Glass & ceramic machining
•Optics Quality Control lab
•Apprentices training (~3*3months)
•General support to DT detector projectsSee link=> https://ep-dep-dt.web.cern.ch/thin-film-glass-service
EP-DT Thin Film and Glass Service (TFG)
Jerome NoelThomas SchneiderMiranda van Stenis Laura Funder (technical student)
More than 50 years growing experience
1DT training seminar T. Schneider 8/4/2020
Florian Jenny(apprentice)
ProductionStandard service
R&D
EP-DT-TFG Anti Reflective coating
2DT training seminar T. Schneider 8/4/2020
Improve Transmission of LHCb RICH1 quartz
exit window
A thin transparent layer of MgF2 (n2 different to n1
substrate) is applied via thin film coating to reduce
Fresnel reflection . By setting the thickness of the
coating to a quarter wavelength, the second
reflection R2is delayed by λ
2. This opposite light
wave reduces (cancelation) the initial reflection.
Refractive index n2
Refractive index n1
i r
r’
FRESNELReflection(R)
Refraction
I0
2
12
12
nn
nnR
λ/2
EP-DT-TFG Enhanced reflective coating
3DT training seminar T. Schneider 8/4/2020
λ delay
Enhanced reflective coating
Aluminum as very uniform metallic
reflector is deposited on a polished
substrate. On top a dielectric
transparent layer is applied to enhance
the reflectance of the Aluminum layer.
In this case the layer thickness (~ λ/2)
is adjusted such that the 2nd reflection
is delayed by λ. That way the 2
waveforms overlap and add up.
In addition this dielectric layer act as
protection layer for the Aluminum.
(oxidation and mechanical handling)
EP-DT-TFG LHCb RICH1 upgrade
4DT training seminar T. Schneider 8/4/2020
R&D for LHCb RICH1 optics system (status mid 2019)
• Defined recipe for enhanced protected coating according to given requirements (sensitivity of photo detector 250-500nm)
• Test coating on real size flat mirror (Cr, Al, SiO2, HfO2)
• Overcome intrinsic problem of big spherical mirrors (thinner layers @ borders)
• Test coatings on composite samples
16 flat glass mirrors(370mm*440mm) 4 spherical composite mirrors, (740mm*650mm)
Quartz window QC
EP-DT-TFG LHCb RICH1 upgrade
The dimensions of the spherical composite substrates have been adapted to the geometrical limits of the coater.These will be the largest mirror substrates ever treated in the TFG lab.
4 spherical composite mirrors, Diagonal 965mm
5DT training seminar J. Nôel 8/4/2020
EP-DT-TFG LHCb RICH1 upgrade
Big Coater “clean” room B108
Vacuum Tankinner space Ø970 mm
6
E beamPower rack
Process protocolLab view softwareData Acquisition
Cryo pump :Vacuum : 10E-8 mbar
Inficon module :Thickness measurementThermal source processingRotation 60 rpm
DT training seminar J. Nôel 8/4/2020
EP-DT-TFG LHCb RICH1 upgrade
Rotating substrate holder
X-talThicknessmeasurement
T° sensors
7
Electron Beam source4 crucibles
Thermal sources2 slots :
spring or crucible
Big Coater “clean” room B108
DT training seminar J. Nôel 8/4/2020
8
EP-DT-TFG LHCb RICH1 upgrade
LHCB spherical composite mirrors thin film recipe
Adherence layerCr
1st
Metallic reflexionAl
2ndSiO2
3rd
HfO2
4th
Ther
mal
Ther
mal
E B
eam
E B
eam
Enhancement of the reflectivity+ protecting the Al
DT training seminar J. Nôel 8/4/2020
Dielectric layers with ~30% of thickness variationAt the corners of the big spherical composite mirrors.
Big Coater 108 E beam : relative thickness distribution on a turning substrate
Dielectric layers with 10% of thickness variationAt the corners of the small rich mirror
EP-DT-TFG LHCb RICH1 upgrade
9DT training seminar J. Nôel 8/4/2020
Big Coater E beam : Thickness variation = reflective variation
Working range of the optical chain is within a wavelength of 275nm - 390nm
EP-DT-TFG LHCb RICH1 upgrade
10
Small mirrors
Big mirrors
Agreed requirements for Work Package TFG -LHCb RICH1 (EDMS 2060758) 2017Big spherical mirrors:Reflectivity >90% in the range 280nm-380nmSmall flat mirrors: Reflectivity >90% in the range 280nm-500nm
DT training seminar J. Nôel 8/4/2020
Simulation of the thickness variation on the 4 RICH spherical composite mirrors
10% < Thickness variation < 30%
LHCB Beam pipe center
EP-DT-TFG LHCb RICH1 upgrade
11
Coater center
Thickness variation < 10%
DT training seminar J. Nôel 8/4/2020
1- Mask the over exposed areas :Adding a mask in between the E beam and the substrate
Big coater upgrade to make dielectric layers uniform with the E beam on the big substrate
EP-DT-TFG LHCb RICH1 upgrade
Shaping and sizing the mask.
12DT training seminar J. Nôel 8/4/2020
Precise positioning of the shadow mask for the reproducibility
LED projector Mask Shadow of the Mask
EP-DT-TFG LHCb RICH1 upgrade
Substrate target
Chrome evaporation's mapping with a fix substrate
13DT training seminar J. Nôel 8/4/2020
2- Electron Beam upgrade for big substrate :
EP-DT-TFG LHCb RICH1 upgrade
14
Our standard :Small spot
Reducing the border effect and stabilize the beam rate deposition :- Software improvement to position the beam spot with higher accuracy.- Beam spot size optimisation to keep angle distribution most constant during the process.
The walls of the deep groove acts as a mask
To achieve the thickness with the mask we need to do two deep grooves.
Two stepsSpot beam
One stepNEW square beam
Two stepsSpot beam
One stepNEW square beam
DT training seminar J. Nôel 8/4/2020
EP-DT-TFG LHCb RICH1 upgrade
Reflectivity measured on samples with all the upgrades
15
Working range of the optical chain is nowwithin a wavelength of 260nm - 500nm
Small mirrors
Big mirrors
DT training seminar J. Nôel 8/4/2020
Reflectivity > 90% in the range of 270nm to 500nmup to Ø965mm substrate.
EP-DT-TFG LHCb RICH1 upgrade
As good uniformity results on big spherical as on small flat mirrors!!!
16
Thickness variation < 10%
Achievements of 2019 upgrade with mask and E-beam optimisation:
Small mirrors are ongoing 4 out of 22 are done.We are ready to do the 4 big mirrors
DT training seminar J. Nôel 8/4/2020
EP-DT-TFG Questions
17DT training seminar L. Funder 8/4/2020
Questions?