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45° AOI Beamsplitter Compensation Plates, UV Fused Silica for UV to NIR


  • Antireflective Coating on Both Surfaces
  • Optimized for 45° Angle of Incidence
  • Broadband Wavelength Ranges in the UV, Visible, and NIR
  • Round and Rectangular Options

BCP44R

AR Coating Range: 600 nm to 1700 nm
25 mm x 36 mm x 1 mm

BCP4510

AR Coating Range: 700 mm to 1100 nm
Ø1" and 5 mm Thick

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Features

  • AR Coatings Customized for 45° AOI,  with Broadband Wavelength Ranges:
    • 250 nm - 450 nm with <1.0% at 45° AOI
    • 350 nm - 1100 nm with <2.0% at 45° AOI
    • 400 nm - 700 nm with <1.0% at 45° AOI
    • 600 nm - 1700 nm with <1.5% at 45° AOI
    • 700 nm - 1100 nm with <1.0% at 45° AOI
    • 1200 nm - 1600 nm with <1.0% at 45° AOI
  • Ø1" Round and 25 mm x 36 mm Rectangular Options 
  • Round Compensation Plates have 30 arcmin Back Surface Wedge to Minimize Ghosting
  • UV Fused Silica Substrate (Transmission Curve)

These Beamsplitter Compensation Plates are designed for use in Michelson and other interferometers, and they are additionally ideal as 45° windows in optical enclosures. The substrate material of both the rectangular and wedged round versions of these beamsplitter compensation plates is UV fused silica. For best results when pairing a plate with beamsplitter, choose the two so that their substrate materials and thicknesses are the same. When these plates are used as 45° windows in optical enclosures, the 1.0 mm thick rectangular plates are preferred where space is limited and the wedged round plates when it is of interest to suppress ghosting.

As both surfaces of these beamsplitter compensation plates are antireflection (AR) coated for a 45° angle of incidence (AOI), they are optimally oriented at a 45° angle to the incident light. This is in contrast to our other UV Fused Silica AR coated wedged and flat windows that are designed to be used with their coated surfaces oriented normally to the incident light (0° AOI). The coated surfaces of the 25 mm x 36 mm x 1 mm rectangular versions are parallel with one another and perpendicular to the ground edge. The Ø1" round versions are 5 mm thick and feature a front surface that is perpendicular to the ground edge and a back surface that makes a 30 arcmin angle with the ground edge. The slight wedge on the back surface of the round plates causes any reflected light to diverge from the incident light path, which acts to suppress ghosting and fringe patterns that may arise from reflections.

UV-grade fused silica is well suited for applications that benefit from increased transmission deeper into the UV than N-BK7. UV fused silica also offers a lower index of refraction for a given wavelength, better homogeneity, and a lower coefficient of thermal expansion than N-BK7. Approximately 4% of the incident light is reflected from uncoated UV silica surfaces. The broadband AR coatings on these 45° AOI beamsplitter compensation plates reduce the average reflection to less than 1.0% to 2.0%, depending on the wavelength range of the coating.

When used in a Michelson or similar interferometer, the plate is paired with a beamsplitter as shown in the image above to compensate for the non-zero thickness of the beamsplitter. Placing the compensation plate between the beamsplitter and the fixed mirror essentially sandwiches the reflective surface of the beamsplitter between two equal thicknesses of glass, so that this composite beamsplitter contributes the same optical path length, dispersion, and other optical effects for both arms of the interferometer. Without the plate, light travelling the fixed mirror arm travels through a total of one third the thickness of glass as light travelling through the translating mirror arm.  

In addition to the UV fused silica flat and wedged windows offered here, Thorlabs also offers flat and wedged windows with other substrate materials (see the selection guides below). Additionally, flat and wedged windows with custom sizes and thicknesses are available; please contact Tech Support for more information.

Flat Window Selection Guide
Wavelength Range Substrate Material
150 nm - 5.0 μm Sapphire
180 nm - 8.0 μm Calcium Fluoride (CaF2)
185 nm - 2.1 μm UV Fused Silica
200 nm - 6.0 μm Magnesium Fluoride (MgF2)
250 nm - 1.6 µm UV Fused Silica, for 45° AOI
300 nm - 3 µm Infrasil®
350 nm - 2.0 μm N-BK7
600 nm - 16 µm Zinc Selenide (ZnSe)
1.2 - 8.0 μm Silicon (Si)
2.0 - 16 μm Germanium (Ge)
3 - 5 μm Barium Fluoride (BaF2)
V-Coated Laser Windows


Wedged Window Selection Guide
Wavelength Range Substrate Material
150 nm - 5.0 µm Sapphire
180 nm - 8.0 µm Calcium Fluoride (CaF2)
185 nm - 2.1 μm UV Fused Silica
200 nm - 6.0 µm Magnesium Fluoride (MgF2)
200 nm - 11 µm Barium Fluoride (BaF2)
250 nm - 1.6 µm UV Fused Silica for 45° AOI
350 nm - 2.0 μm N-BK7
600 nm - 16 µm Zinc Selenide (ZnSe)
1.2 - 8.0 µm Silicon (Si)
2.0 - 16 µm Germanium (Ge)
V-Coated Wedged Windows

Posted Comments:
user  (posted 2018-08-28 13:15:54.01)
Is the LIDT for these plates similar to that of these windows? https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=3983 Are the 700-1100nm and the 650-1050nm coatings similar with regards to LIDT? Thanks
YLohia  (posted 2018-08-30 02:33:45.0)
Hello, thank you for contacting Thorlabs. You are correct -- the LIDT of this would be similar to that of our standard B coatings. That being said, we have not performed conclusive damage threshold testing for these windows.
user  (posted 2017-12-17 22:40:44.863)
A 3mm half inch version to match the BSW25 beamsplitter would be nice :-)
nbayconich  (posted 2017-12-20 05:12:40.0)
Thank you for your feedback. I have forwarded your request to our R&D team for future consideration. We can provide custom versions of these compensation plates. If you need custom sized optics please contact us at techsupport@thorlabs.com.
Window Selection Guide (Table Sorted by Wavelength)
Substrate and Window Type Wavelength Range Available AR Coatings Reflectance over AR Coating Rangea Transmission Data Reflectance Data
Sapphire:
Flat or Wedged
150 nm - 5.0 μm Uncoated -
Raw Data
-
 -D Coating, 1.65 - 3.0 µm Ravg < 1.0% at 0° AOI
Raw Data

Raw Data
 -E1 Coating, 2.0 - 5.0 µm Ravg < 1.50%, Rabs < 3.0% (per Surface, 2.0 - 5.0 µm);
Ravg < 1.75% (per Surface, 2.0 - 4.0 µm) at 0° AOI

Raw Data

Raw Data
Calcium Fluoride (CaF2):
Flat or Wedged
180 nm - 8.0 μm  Uncoated -
Raw Data
-
-D Coating, 1.65 - 3.0 µm Ravg < 1.0%; Rabs < 2.0% at 0° AOI
Raw Data

Raw Data
UV Fused Silica:
FlatWedgedV-Coated Flat, or
V-Coated Wedged
185 nm - 2.1 μm Uncoated
(Flat or Wedged)
-
Raw Data
-
-UV Coating, 245 - 400 nm
(Flat or Wedged)
Ravg < 0.5% at 0° AOI -
Raw Data
-C3 Coating, 261 - 266 nm
(V-Coated)
Ravg < 0.5% at 0° AOI - Click to View Index Plot
Raw Data
-C6 Coating, 350 - 450 nm
(V-Coated)
Ravg < 0.5% at 0° AOI - Click to View Index Plot
Raw Data
 -A Coating, 350 - 700 nm 
(Flat or Wedged)
Ravg < 0.5% at 0° AOI -
Raw Data
 -B Coating, 650 - 1050 nm 
(Flat or Wedged)
Ravg < 0.5% at 0° AOI -
Raw Data
 -C Coating, 1050 - 1700 nm 
(Flat or Wedged)
Ravg < 0.5% at 0° AOI -
Raw Data
Magnesium Fluoride (MgF2):
Flat or Wedged
200 nm - 6.0 μm Uncoated -
Raw Data
-
Barium Fluoride (BaF2):
Wedged 
(Flat BaF2 Windows
Available Below)
200 nm - 11 µm Uncoated -
Raw Data
-
-E1 Coating, 2 - 5 µm  Ravg < 1.25%; Rabs < 2.5%  at 0° AOI
Raw Data
Icon
Raw Data
UV Fused Silica, for 45° AOI:
Flat or Wedged
250 nm - 1.6 µm Coating for 
250 nm - 450 nm
Ravg < 1.0% at 45° AOI info
Raw Data
Coating for
350 nm - 1100 nm
Ravg < 2.0% at 45° AOI info
Raw Data
Coating for
400 nm - 700 nm
Ravg < 1.0% at 45° AOI info
Raw Data
Coating for
600 nm - 1700 nm
Ravg < 1.5% at 45° AOI info
Raw Data
Coating for
700 nm - 1100 nm
Ravg < 1.0% at 45° AOI info
Raw Data
Coating for
1200 nm - 1600 nm
Ravg < 1.0% at 45° AOI info
Raw Data
Infrasil®:
Flat
300 nm - 3 µm Uncoated -
Raw Data
 -
N-BK7:
FlatWedgedV-Coated Flat, or
V-Coated Wedged
350 nm - 2.0 μm Uncoated
(Flat or Wedged)
-
Raw Data
-
 -A Coating, 350 - 700 nm  
(Flat or Wedged)
Ravg < 0.5% at 0° AOI -
Raw Data
-C7 Coating, 400 - 700 nm
(V-Coated)
Ravg < 0.5% at 0° AOI - Click to View Index Plot
Raw Data
-C10 Coating, 523 - 532 nm (V-Coated) Ravg < 0.5% at 0° AOI - Click to View Index Plot
Raw Data
-C11 Coating, 610 - 860 nm 
(V-Coated)
Ravg < 0.5% at 0° AOI - Click to View Index Plot
Raw Data
-B Coating, 650 - 1050 nm 
(Flat or Wedged)
Ravg < 0.5% at 0° AOI -
Raw Data
-C13 Coating, 700 - 1100 nm 
(V-Coated)
Ravg < 0.5% at 0° AOI - Click to View Index Plot
Raw Data
C14 Coating, 1047 - 1064 nm
(V-Coated)
Ravg < 0.5% at 0° AOI - Click to View Index Plot
Raw Data
-C15 Coating, 523 - 532 nm
& 1047 - 1064 nm
(V-Coated) 
Ravg < 0.5% at 0° AOI - Click to View Index Plot
Raw Data
-C Coating, 1050 - 1700 nm 
(Flat or Wedged)
Ravg < 0.5% at 0° AOI -
Raw Data
Zinc Selenide (ZnSe):
Flat or Wedged
600 nm - 16 µm Uncoated -
Raw Data
-
-D Coating, 1.65 - 3.0 µm Ravg < 1.0%; Rabs < 2.0% at 0° AOI
Raw Data

Raw Data
-E4 Coating, 2 - 13 µm
(Only Flat)
Ravg < 3.5%; Rabs < 6% at 0° AOI
Raw Data

Raw Data
-E2 Coating, 4.5 - 7.5 µm
(Only Flat)
Ravg < 1.0%; Rabs < 2.0% at 0° AOI
Raw Data

Raw Data
-E3 Coating, 7 - 12 µm
(Only Wedged)
Ravg < 1.0%; Rabs < 2.0% at 0° AOI
Raw Data
Icon
Raw Data
-G Coating, 7 - 12 µm
(Only Flat)
Ravg < 1% at 0° AOI
Raw Data

Raw Data
Silicon (Si):
Flat or Wedged
1.2 - 8.0 μm Uncoated -
Raw Data
-
 -E1 Coating, 2 - 5 µm
(Only Wedged)
Ravg < 1.25%; Rabs < 2.5% at 0° AOI
Raw Data
Icon
Raw Data
-E Coating, 3 - 5 µm
(Only Flat)
Ravg < 2% at 0° AOI
Raw Data

Raw Data
Germanium (Ge):
Flat or Wedged
2.0 - 16 μm Uncoated -
Raw Data
-
-C9 Coating, 1.9 - 6 µm
(Only Flat)
Ravg < 2% at 0° AOI
Raw Data

Raw Data
-G Coating, 7 - 12 µm
(Only Flat)
Ravg < 1% at 0° AOI
Raw Data

Raw Data
-E3 Coating, 7 - 12 µm
(Only Wedged)
Ravg < 1.0%; Rabs < 2.0% at 0° AOI
Raw Data
Icon
Raw Data
Barium Fluoride (BaF2):
Flat 
(Wedged BaF2 Windows Available Above)
3 - 5 μm -E Coating, 3 - 5 µm Ravg < 2% at 0° AOI
Raw Data

Raw Data
  • Reflectance is given per surface and each window is coated on both sides.

Rectangular Plates, with Parallel Front and Back Surfaces

Profile of Rectangular Plate
Click to Enlarge

Note: Not Drawn to Scale
Coated surfaces are parallel with one another and perpendicular to the ground edge.
Common Specifications
Substrate Material UV Fused Silicaa
Dimensions 25 mm x 36 mm x 1 mm
Dimensional Tolerance ±0.1 mm
Clear Aperture >22.5 mm x 32.4 mm
Surface Quality 40-20 Scratch-Dig
Transmitted Wavefront Error <λ/4 at 633 nm
Parallelism <3 arcmin
  • Click Link for Detailed Specifications on the Substrate
Item # BCP41R BCP42R BCP43R BCP44R BCP45R BCP46R
Wavelength Range of AR Coating 250 nm - 450 nm 350 nm - 1100 nm 400 nm - 700 nm 600 nm - 1700 nm 700 nm - 1100 nm 1200 nm - 1600 nm
Average Reflectance Over Coating Range info
<1.0% at 45° AOI
info
<2.0% at 45° AOI
info
<1.0% at 45° AOI
info
<1.5% at 45° AOI
info
<1.0% at 45° AOI
info
<1.0% at 45° AOI
45° AOI Transmittance and  Reflectance Data info info info info info info
Raw Data for All Plots BCP41R BCP42R BCP43R BCP44R BCP45R BCP46R
Compatible Beamsplitters UVFS Plate UVFS Plate UVFS Plate UVFS Plate UVFS Plate UVFS Plate
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
BCP41R Support Documentation
BCP41RCustomer Inspired! 25 x 36 mm UVFS Beamsplitter Compensator Plate, 45° AOI AR Coating: 250 - 450 nm, t = 1 mm
$125.53
Today
BCP42R Support Documentation
BCP42RCustomer Inspired! 25 x 36 mm UVFS Beamsplitter Compensator Plate, 45° AOI AR Coating: 350 - 1100 nm, t = 1 mm
$125.53
Today
BCP43R Support Documentation
BCP43RCustomer Inspired! 25 x 36 mm UVFS Beamsplitter Compensator Plate, 45° AOI AR Coating: 400 - 700 nm, t = 1 mm
$125.53
Today
BCP44R Support Documentation
BCP44RCustomer Inspired! 25 x 36 mm UVFS Beamsplitter Compensator Plate, 45° AOI AR Coating: 600 - 1700 nm, t = 1 mm
$125.53
Today
BCP45R Support Documentation
BCP45RCustomer Inspired! 25 x 36 mm UVFS Beamsplitter Compensator Plate, 45° AOI AR Coating: 700 - 1100 nm, t = 1 mm
$125.53
Today
BCP46R Support Documentation
BCP46RCustomer Inspired! 25 x 36 mm UVFS Beamsplitter Compensator Plate, 45° AOI AR Coating: 1200 - 1600 nm, t = 1 mm
$125.53
Today

Round Plates, with Wedged Back Surface

Profile of Rectangular Plate
Click to Enlarge

Note: Not Drawn to Scale
The 30 arcmin wedge, in addition to the AR coating, reduces unwanted interference effects (e.g. ghost images) caused by the interaction of light from the front and back surfaces; light reflected from the wedged surface diverges.
Common Specifications
Substrate Material UV Fused Silicaa
Diameter Ø1"
Diameter Tolerance +0.0 mm/ -0.2 mm
Thickness 5 mm
Thickness Tolerance ±0.1 mm
Wedge Angle of Back Surface 30 arcmin
Wedge Tolerance ±10 arcmin
Clear Aperture >Ø22.86 mm
Surface Quality 20-10 Scratch-Dig
Surface Flatness <λ/10 at 633 Over Clear Aperture
  • Click Link for Detailed Specifications on the Substrate
Item # BCP4110 BCP4210 BCP4310 BCP4410 BCP4510 BCP4610
Wavelength Range of AR Coating 250 nm - 450 nm 350 nm - 1100 nm 400 nm - 700 nm 600 nm - 1700 nm 700 nm - 1100 nm 1200 nm - 1600 nm
Average Reflectance Over Coating Range info
<1.0% at 45° AOI
info
<2.0% at 45° AOI
info
<1.0% at 45° AOI
info
<1.5% at 45° AOI
info
<1.0% at 45° AOI
info
<1.0% at 45° AOI
45° AOI Transmittance and  Reflectance Data info info info info info info
Raw Data for All Plots BCP4110 BCP4210 BCP4310 BCP4410 BCP4510 BCP4610
Compatible Beamsplitters UVFS Plate UVFS Plate UVFS Plate UVFS Plate UVFS Plate UVFS Plate
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
BCP4110 Support Documentation
BCP4110Customer Inspired! Ø1" UVFS Beamsplitter Compensation Plate, 45° AOI AR Coating: 250 - 450 nm, t = 5 mm
$104.97
Today
BCP4210 Support Documentation
BCP4210Customer Inspired! Ø1" UVFS Beamsplitter Compensation Plate, 45° AOI AR Coating: 350 - 1100 nm, t = 5 mm
$104.97
Today
BCP4310 Support Documentation
BCP4310Customer Inspired! Ø1" UVFS Beamsplitter Compensation Plate, 45° AOI AR Coating: 400 - 700 nm, t = 5 mm
$104.97
Today
BCP4410 Support Documentation
BCP4410Customer Inspired! Ø1" UVFS Beamsplitter Compensation Plate, 45° AOI AR Coating: 600 - 1700 nm, t = 5 mm
$104.97
Today
BCP4510 Support Documentation
BCP4510Customer Inspired! Ø1" UVFS Beamsplitter Compensation Plate, 45° AOI AR Coating: 700 - 1100 nm, t = 5 mm
$104.97
Today
BCP4610 Support Documentation
BCP4610Customer Inspired! Ø1" UVFS Beamsplitter Compensation Plate, 45° AOI AR Coating: 1200 - 1600 nm, t = 5 mm
$104.97
Today
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