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Technical Specifications of VLS- Plane Gratings for ARPES and XMCD beamlines
Item:VLS- Plane Gratings for ARPES and XMCD beamlines
Quantity: 5 (Five)
Important note to bidders:
The price of the each grating shall be quoted separately
A bidder may bid for one or more gratings mentioned in the tender
Bid evaluation criteria:
The price of the each grating will be compared separately.
The supplier should be ready to provide one or more number of gratings pout of
the five gratings set.
1. Scope of the Tender
The scope of the tender is the supply of five Varied Line Spacing Plane Gratings
(VLS-PG) that will be used for the Angle Resolved Photo-Electron Spectroscopy
(ARPES) and X-ray Magnetic Circular Dichroism (XMCD) beamlines on Indus-2
synchrotron source. These beamlines are proposed to be installed on a planar
permanent magnet and APPLE-II type undulators, respectively.
2. Bidder qualification
i) The supplier shall be an original manufacturer (OEM) of the item, or an authorized
supplier of the OEM, or standard synchrotron beamline component supplier.
ii) The company should have supplied at least six soft x-ray gratings in the past two
years for synchrotron beamlines. The list of beamlines where similar gratings have
been supplied by the company must be provided with the offer.
iii) The supplier should have the facility for the metrology of these gratings. The
details of the instruments available with the supplier for this purpose shall be
mentioned in the offer.
3. Beamline details
3.1 ARPES beamline:
A schematic optical design of the beamline is shown in Fig. 1. The monochromator
design is a constant included angle, variable line spacing grating based system. The first
2
optical element of the beamline is a toroidal mirror M1 that focuses the beam on to the
entrance slit S1. The low energy radiation is reflected by the mirror SM2 and falls on the
grating. The higher energy radiation is reflected by the mirror SM1 on to the grating.
The gratings proposed to be purchased for this beamline are named G1A, G2A, and
G3A. G1A operates in the energy range: 80 eV to 270 eV, G2A operates in the energy range:
215 eV to 500 eV, and G3A operates in the energy range: 430 eV to 1000 eV. The gratings
are rotated for wavelength selection and the mirrors are kept fixed. The gratings focus the x-
rays on the exit slit S2. The x-rays are finally focused on the sample using the toroidal mirror
M2.
Side view:
Top view:
Figure 1. Optical layout of ARPES beamline (Not to scale). The circled part shows the
position of the monochromator where the gratings will be placed.
(all distances are given in mm)
VLS-PG
S2
Toroidal
Mirror, M1
S1
SM1 SM2
Toroidal
Mirror, M2
Sample
S2 3600 1500 3400.3 9000
18500 M1 S1 (4000)
1500 VLS-PG 997.6
(400)
SM1
(SM2)
3
3.2 XMCD beamline:
A schematic optical design of the beamline is shown in Fig. 2. The beamline is based
on a Variable Included Angle Variable Line Spacing Plane Grating (VLS-PG)
monochromator design. In this beamline, the first optical component is a water cooled
toroidal mirror (TM1) that focuses the SR beam in the sagittal direction on to the water
cooled slit S1 of the monochromator. The second optical element, a spherical mirror SM,
which remains fixed during the energy scan, and focuses the beam behind the VLS-PG . A
long plane mirror between the spherical mirror and the grating provides the variable included
angles to the grating.
The gratings proposed to be purchased for this beamline are G1X and G2X. Grating
G1X operates in the energy range: 300 eV to 1,000 eV and the grating G2X operates in the
energy range: 600 eV to 2,000 eV. The gratings focus the x-rays on the exit slit S2. The x-ray
is finally focused on the sample using the toroidal mirror M2. The plane mirror and the
grating movements are used to select the energy.
Side view:
Top view:
Figure 2. Optical layout of XMCD beamline (Not to scale). The circled part shows the
position of the monochromator where the gratings will be placed.
(all distances are given in mm)
S2 3600 1500 1200 1500 VLS-PG SM
8000
S1 PM
M1
& M2
VLS-PG
S2
TM1
PM
M1 & M2
Expt-1 Expt-2
S1 SM
4086.6
0
18500 TM1
486.6
4
4. Technical Specifications
In this section, the detail technical specifications of the gratings are described.
The groove density ( in units of lines/mm) variation of the VLS-PG is defined by the
following equation for all the gratings:
N(w) = No (1+a1w+ a2w2+ a3w
3+…)
where “No” is the groove density at the centre of the grating, and “w” is the distance
measured from the centre of the grating along the meridional axis.
All the gratings will be mounted in the inverted geometry, i.e., the grating rulings are
facing downwards.
Detail specifications of the gratings are given in the following Tables.
Table 1: Technical specification of the grating (G1A) for the ARPES beamline,
for the 80 eV to 270 eV energy range.
Grating G1A
Shape Planar
Grating type Laminar (VLS)
Geometrical dimension 130 × 30 mm2
(± 0.1 mm in both dim.)
Optical dimension 120× 20 mm2
(± 1 mm in both dim.)
Thickness 40 ± 0.5 mm
Substrate material Silicon
RMS slope error of the starting
substrate
Meridional : ≤ 0.15 arcsec
Sagittal: ≤ 1.75 arcsec
RMS substrate roughness ≤ 0.3 nm
Coating material1 Au or Pt
Coating thickness 30 ± 10 nm
Groove density at the center of
the grating (No)
770 lines/mm ± 2 lines/mm
Groove axis
Perpendicular to the long axis (meridional
axis) within ± 0.5o
Grating parameter 2G/L = 0.6 ± 25 % ,
3GD = 19 ± 20% nm
Grating spacing parameters
a1= - 5.52×10-4
mm-1
(±1 %)
a2= 2.28 × 10-7
mm-2
(± 20%)
The value of a3 for grating G1A is, -8.3 × 10-11
mm-3
. The design value of a3 for the grating
should be within ± 10% .
5
Table 2: Technical specification of the grating (G2A) for the ARPES beamline,
for the 215 eV to 500 eV energy range.
Grating G2A
Shape Planar
Grating type Laminar (VLS)
Geometrical dimension 130 × 30 mm2
(± 0.1 mm in both dim.)
Optical dimension 120 × 20 mm2
(± 1 mm in both dim.)
Thickness 40 ±0.5 mm
Substrate material Silicon
RMS slope error of the starting
substrate
Meridional : ≤ 0.15 arcsec
Sagittal: ≤ 3 arcsec
RMS substrate roughness ≤ 0.3 nm
Coating material1 Au or Pt
Coating thickness 30 ± 10 nm
Groove density at the center of
the grating (No)
700 lines/mm ± 2 lines/mm
Groove axis Perpendicular to the long axis (meridional
axis) within ± 0.5o
Grating parameters 2G/L = 0.6 ± 25% ,
3GD = 17 ± 20% nm
Grating spacing parameters a1= - 5.54×10-4
mm-1
(±1 %)
a2= 2.30 × 10-7
mm-2
(± 20%)
The value of a3 for grating G2A is, - 8.5 × 10-11
mm-3
. The design value of a3 for the
grating should be within ± 10% .
Table 3: Technical specification of the grating (G3A) for the ARPES beamline,
for the 430 eV to 1,000 eV energy range.
Grating G3A
Shape Planar
Grating type Laminar or blazed (VLS)
Geometrical dimension 130 × 30 mm2
(± 0.1 mm in both dim.)
Optical dimension 120 × 20 mm2
(± 1 mm in both dim.)
Thickness 40 ± 0.5 mm
Substrate material Silicon
RMS slope error of the starting
substrate
Meridional : ≤ 0.15 arcsec
Sagittal: ≤ 3 arcsec
RMS substrate roughness ≤ 0.3 nm
Coating material1 Au or Pt
Coating thickness 30 ± 10 nm
Groove density at the center of
the grating (No)
1400 lines/mm ± 2 lines/mm
Groove axis Perpendicular to the long axis (meridional
axis) within ± 0.5o
Grating parameters 2G/L = 0.6 ± 25 % ,
3GD = 8 ± 25 %
nm
Grating spacing parameters a1= - 5.54×10-4
mm-1
(±1 %)
a2= 2.30 × 10-7
mm-2
(± 20%)
The value of a3 for grating G3A is, - 8.5 × 10-11
mm-3
. The design value of a3 for the grating
should be within ± 70% .
6
Table 4: Technical specification of the grating (G1X) for the XMCD beamline,
for the 300 eV to 1,000 eV energy range.
Grating G1X
Shape Planar
Grating type Laminar (VLS)
Geometrical dimension 150 mm × 30 mm (± 0.1 mm in both dim.)
Optical dimension 140 mm × 20 mm (± 1 mm in both dim.)
Thickness 40 ± 0.5 mm
Substrate material Silicon
RMS slope error of the starting
substrate
Meridional: ≤ 0.15 arcsec
Sagittal: ≤ 2.5 arcsec
RMS substrate roughness ≤ 0.3 nm rms
Coating material1 Au or Pt
Coating thickness 30 ± 10 nm
Groove density at the center of
the grating (No)
900 lines/mm ± 2 lines/mm
Groove axis Perpendicular to the long axis (meridional
axis) within ±0.5o
Grating parameters 2G/L = 0.6± 25% ;
3GD = 11 ± 25% nm
Grating spacing parameters a1 = -5.55×10-4
mm-1
(± 2 %)
a2 = 2.31×10-7
mm-2
(± 20 %)
The value of a3 for grating G1X is, - 8.5 × 10-11
mm-3
. The design value of a3 for the
grating should be within ± 40% .
Table 5: Technical specification of the grating (G2X) for the XMCD beamline,
for the 600 eV to 2,000 eV energy range.
Grating G2X
Shape Planar
Grating type Laminar (VLS)
Geometrical dimension 150 mm × 30 mm (± 0.1 mm in both dim.)
Optical dimension 140 mm × 20 mm (± 1 mm in both dim.)
Thickness 40 ± 0.5 mm
Substrate material Silicon
RMS slope error of the starting
substrate
Meridional: ≤ 0.15 arcsec
Sagittal: ≤ 2.5 arcsec
RMS substrate roughness ≤ 0.3 nm rms
Coating material1 Au or Pt
Coating thickness 30 ± 10 nm
Groove density at the center of
the grating (No)
1800 lines/mm ± 2 lines/mm
Groove axis Perpendicular to the long axis (meridional
axis) within ±0.5o
Grating parameters 2G/L = 0.6± 33% ;
3GD = 6 ± 30% nm
Grating spacing parameters a1 = -5.55×10-4
mm-1
(± 1 %)
a2 = 2.31×10-7
mm-2
(± 20 %)
The value of a3 for grating G2X is, -8.5×10-11
mm-3
. The design value of a3 for the grating
should be within ± 40% .
7
Points common to the Table 1 to 4
1 A Pt binding layer or any compatible binding layer to the energy range of operation of the
gratings shall be mentioned in the offer. The details of the binding layer and the material of
the coating layer will be decided at the design stage.
2 G/L: Groove Width/ Groove Spacing
3 GD: Groove Depth
Common specifications for all the gratings:
5. Holding Mechanism
The gratings are to be manufactured in such a way, that they can be firmly held in the
respective grating holders in the monochromator. The preferred grating profile for holding is
shown in Fig. 3. If the supplier wants to use any other profile to hold the grating, then it shall
be mentioned in the quotation. Please note that the scheme and all the dimensions shown for
the grooves at the bottom of the grating are tentative and will be decided at the time of the
design review, after the order is placed.
Figure 3: A schematic layout of the preferred grating holder profile. The dimensions of
the groove are tentative and will be decided at the design stage. All dimensions are in
mm. Typical tolerance on groove width and height is ± 0.1 mm. All other dimensions and
tolerances are as per the Tables 1 to 5.
6. Thermal Load and Cooling Mechanism
The maximum thermal load on the gratings is 60 watt (0.15 W/mm2). A cooling
mechanism (a tentative scheme is shown in Fig. 4) for the gratings will be a part of the
monochromator. The side face of the gratings ( length x height) where the cooling copper
block is held, should be polished to < 1 micron meter rms roughness.
This tender only covers the supply of the gratings. The installation, mounting, and
fixing of the gratings is not within the scope of the present tender.
8
Figure 4: A schematic layout of the side cooling mechanism for the gratings
7. Design Review
The design will be reviewed and approved by RRCAT before commencing the
fabrication process of the gratings. All necessary information about the beamline required for
the design of the grating will be provided after the purchase order. However it is the
responsibility of the supplier to ensure the performance of the grating.
8. Safe packing
The gratings shall be in OEM packing. They shall be packed with sufficient care so
that they do not undergo any damage during transit and withstand tropical weather during the
transport. The grating shall be packed and sealed in dry nitrogen gas or in a similar inert
atmosphere. The packing shall ensure that there is no deterioration in the performance of the
gratings at RRCAT with respect to that in factory. Shock sensor shall be provided on the
packing box.
9. Acceptance Criteria
The suppliers shall provide the test report for the following measurements:
Before the start of groove manufacturing:
1. Roughness and slope error measurement of the substrate shall be provided,
2. The design of the grating grooves and the calculated diffraction efficiency curves
shall also be provided.
Grating Length 130/150 mm
40 mm
9
The report of the above test will need approval of RRCAT before the fabrication of
the gratings.
After the fabrication of the grooves and before shipment:
1 Measurement of groove density No shall be carried out.
2 Measurement of groove profile of the gratings as per the finalized design will also be
carried out.
All the values of these tests shall be as per the values mentioned in Table 1-5.
The test reports should be supplied to RRCAT before the shipment of the gratings.
Only after the acceptance of the test reports by RRCAT in writing, the gratings should be
shipped.
Compliance chart
The supplier must fill the following compliance chart and send it as a part of the quotation:
S.
No Tender requirements Supplier’s compliance
1 The supplier should quote separately for various gratings
2
Bidder qualification:
i. The supplier shall be an original manufacturer (OEM) of
the item, or an authorized supplier of the OEM, or
standard synchrotron beamline component supplier.
ii. The company shall have supplied at least six soft X-ray
gratings in the past three years for Synchrotron
beamlines. The list of beamlines where similar gratings
have been supplied by the company shall be provided
with the offer.
iii. The supplier shall have the facility for the metrology of
these gratings. The details of the instruments available
with the supplier shall be mentioned in the offer.
Technical specification of the grating (G1A)
Parameter Indent specification Supplier’s value Remark
Grating G1A
Shape Planar
Grating type Laminar (VLS)
Geometrical dimension 130 × 30 mm2
(± 0.1 mm in both dim.)
Optical dimension 120× 20 mm2
(± 1 mm in both dim.)
Thickness 40 ± 0.5 mm
Substrate material Silicon
RMS slope error of the
starting substrate
Meridional: ≤ 0.15 arcsec
Sagittal: ≤ 1.75 arcsec
RMS substrate roughness ≤ 0.3 nm
Coating material Au or Pt
Coating thickness 30 ± 10 nm
Groove density at the center 770 lines/mm
10
of the grating (No) ± 2 lines/mm
Groove axis
Perpendicular to the long
axis (meridional axis) within
± 0.5o
Grating parameter G/L = 0.6 ± 25% ,
GD = 19 ± 20 % nm
Grating spacing parameters
a1= - 5.52×10-4
mm-1
(±1 %)
a2= 2.28 × 10-7
mm-2
(± 20%)
Technical specification of the grating (G2A)
Parameter Indent specification Supplier’s value Remark
Grating G2A
Shape Planar
Grating type Laminar (VLS)
Geometrical dimension 130 × 30 mm2
(± 0.1 mm in
both dim.)
Optical dimension 120 × 20 mm2
(± 1 mm in
both dim.)
Thickness 40 ±0.5 mm
Substrate material Silicon
RMS slope error of the
starting substrate
Meridional: ≤ 0.15 arcsec
Sagittal: ≤ 3 arcsec
RMS substrate roughness ≤ 0.3 nm
Coating material Au or Pt
Coating thickness 30 ± 10 nm
Groove density at the center
of the grating (No)
700 lines/mm
± 2 lines/mm
Groove axis
Perpendicular to the long
axis (meridional axis) within
± 0.5o
Grating parameter G/L = 0.6 ± 25% ,
GD = 17 ± 20% nm
Grating spacing parameters
a1= - 5.54×10-4
mm-1
(±1 %)
a2= 2.30 × 10-7
mm-2
(± 20%)
Technical specification of the grating (G3A)
Parameter Indent specification Supplier’s value Remark
Grating G3A
Shape Planar
Grating type Laminar or blazed (VLS)
If both available, they may
be quoted separately
Geometrical dimension 130 × 30 mm2
(± 0.1 mm in both dim.)
Optical dimension 120 × 20 mm2
(± 1 mm in both dim.)
Thickness 40 ± 0.5 mm
Substrate material Silicon
RMS slope error of the
starting substrate
Meridional: ≤ 0.15 arcsec
Sagittal: ≤ 3 arcsec
11
RMS substrate roughness ≤ 0.3 nm
Coating material Au or Pt
Coating thickness 30 ± 10 nm
Groove density at the center
of the grating (No)
1400 lines/mm
± 2 lines/mm
Groove axis
Perpendicular to the long
axis (meridional axis) within
± 0.5o
Grating parameter G/L = 0.6 ± 25 %,
GD = 8 ± 25 % nm
Grating spacing parameters
a1= - 5.54×10-4
mm-1
(±1 %)
a2= 2.30 × 10-7
mm-2
(± 20%)
Technical specification of the grating (G1X)
Parameter Indent specification Supplier’s value Remark
Grating G1X
Shape Planar
Grating type Laminar (VLS)
Geometrical dimension 150 mm × 30 mm
(± 0.1 mm in both dim.)
Optical dimension 140 mm × 20 mm
(± 1 mm in both dim.)
Thickness 40 ± 0.5 mm
Substrate material Silicon
RMS slope error of the
starting substrate
Meridional: ≤ 0.15 arcsec
Sagittal: ≤ 2.5 arcsec
RMS substrate roughness ≤ 0.3 nm rms
Coating material Au or Pt
Coating thickness 30 ± 10 nm
Groove density at the center
of the grating (No)
900 lines/mm
± 2 lines/mm
Groove axis
Perpendicular to the long
axis (meridional axis) within
± 0.5o
Grating parameter G/L = 0.6± 25% ;
GD = 11 ± 25% nm
Grating spacing parameters
a1 = -5.55×10-4
mm-1
(± 2 %)
a2 = 2.31×10-7
mm-2
(± 20 %)
Technical specification of the grating (G2X)
Parameter Indent specification Supplier’s value Remark
Grating G2X
Shape Planar
Grating type Laminar or blazed (VLS)
Geometrical dimension 150 mm × 30 mm (± 0.1
mm in both dim.)
Optical dimension 140 mm × 20 mm (± 1
mm in both dim.)
Thickness 40 ± 0.5 mm
Substrate material Silicon
RMS slope error of the
starting substrate
Meridional: ≤ 0.15 arcsec
Sagittal: ≤ 2.5 arcsec
12
RMS substrate roughness ≤ 0.3 nm
Coating thickness 30 ± 10 nm
Coating Material1 Au or Pt
Groove density at the
center of the grating (No)
1800 lines/mm ± 2
lines/mm
Groove axis Perpendicular to the long
axis (meridional axis)
within ±0.5o
Grating parameters 2G/L = 0.6± 33%;
3GD =
6 ± 30% nm
Groove spacing
parameters
a1 = -5.55×10-4
mm-1
(± 1
%)
a2 = 2.31×10-7
mm-2
(± 20
%)
Common points related to all the gratings
1 Holding Mechanism: as per the details in figure 3.
2 Thermal Load and Cooling Mechanism: as per details given in section 6.
The side face of the gratings ( length x height) where the cooling copper
block is held, should be polished to < 1 micron meter rms roughness.
3 Design review: The design will be reviewed and approved by RRCAT
before commencing the fabrication process of the gratings. However it is
the responsibility of the supplier to ensure the performance of the grating.
4 Acceptance Criteria:
The suppliers shall provide the test report for the following measurements:
Before the start of groove manufacturing:
1. Roughness and slope error measurement of the substrate shall be
provided
2. The design of the grating grooves and the calculated diffraction
efficiency curves shall also be provided
The report of the above test will need approval of RRCAT before the
fabrication of the gratings.
After the fabrication of the grooves and before shipment:
1. Measurement of groove density No shall be carried out.
2. Measurement of groove profile of the gratings as per the finalized
design will also be carried out.
All the values of these tests shall be as per the values mentioned in Table
1-5.
The test reports should be supplied to RRCAT before the shipment
of the gratings. Only after the acceptance of the test reports by RRCAT in
writing, the gratings should be shipped.