technical specifications of vls- plane gratings for arpes ... · technical specifications of vls-...

1

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


for the 215 eV to 500 eV energy range.

Grating G2A

Shape Planar




Optical dimension 120 × 20 mm2


Thickness 40 ±0.5 mm



substrate


Sagittal: ≤ 3 arcsec





the grating (No)


Groove axis Perpendicular to the long axis (meridional


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% .


for the 430 eV to 1,000 eV energy range.

Grating G3A

Shape Planar

Grating type Laminar or blazed (VLS)








substrate







the grating (No)




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



6

Table 4: Technical specification of the grating (G1X) for the XMCD beamline,


Grating G1X

Shape Planar


Geometrical dimension 150 mm × 30 mm (± 0.1 mm in both dim.)

Optical dimension 140 mm × 20 mm (± 1 mm in both dim.)




substrate

Meridional: ≤ 0.15 arcsec


RMS substrate roughness ≤ 0.3 nm rms




the grating (No)



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,


Grating G2X

Shape Planar


Geometrical dimension 150 mm × 30 mm (± 0.1 mm in both dim.)

Optical dimension 140 mm × 20 mm (± 1 mm in both dim.)




substrate







the grating (No)



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



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




Optical dimension 120× 20 mm2




RMS slope error of the

starting substrate




Coating material Au or Pt


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


a1= - 5.52×10-4

mm-1

(±1 %)

a2= 2.28 × 10-7

mm-2

(± 20%)



Grating G2A

Shape Planar



(± 0.1 mm in

both dim.)


(± 1 mm in

both dim.)

Thickness 40 ±0.5 mm



starting substrate






Groove density at the center

of the grating (No)

700 lines/mm

± 2 lines/mm

Groove axis



± 0.5o

Grating parameter G/L = 0.6 ± 25% ,

GD = 17 ± 20% nm


a1= - 5.54×10-4

mm-1

(±1 %)

a2= 2.30 × 10-7

mm-2

(± 20%)



Grating G3A

Shape Planar


If both available, they may

be quoted separately








starting substrate



11





of the grating (No)

1400 lines/mm

± 2 lines/mm

Groove axis



± 0.5o

Grating parameter G/L = 0.6 ± 25 %,

GD = 8 ± 25 % nm


a1= - 5.54×10-4

mm-1

(±1 %)

a2= 2.30 × 10-7

mm-2

(± 20%)

Technical specification of the grating (G1X)


Grating G1X

Shape Planar


Geometrical dimension 150 mm × 30 mm


Optical dimension 140 mm × 20 mm





starting substrate







of the grating (No)

900 lines/mm

± 2 lines/mm

Groove axis



± 0.5o

Grating parameter G/L = 0.6± 25% ;

GD = 11 ± 25% nm


a1 = -5.55×10-4

mm-1

(± 2 %)

a2 = 2.31×10-7

mm-2

(± 20 %)

Technical specification of the grating (G2X)


Grating G2X

Shape Planar


Geometrical dimension 150 mm × 30 mm (± 0.1

mm in both dim.)

Optical dimension 140 mm × 20 mm (± 1

mm in both dim.)




starting substrate



12



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.

technical specifications of vls- plane gratings for arpes ... · technical specifications of vls-...

Documents