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Off-Axis Parabolic Mirrors with Through Holes, Unprotected Gold


  • Centered Hole for Superposition of Two Beams
  • Unprotected Gold Coating for 800 nm - 20 µm
  • Available with Reflected Focal Lengths of 2", 4", 6", or 9"

Through Beam
is Parallel to 
Focused Beam

Through Beam
is Parallel to 
Collimated Beam

MPD339H-M03

Ø3", RFL = 9",
Hole Parallel to Focused Beam

MPD269V-M03

Ø2", RFL = 6",
Hole Parallel to Collimated Beam

Related Items


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Fabrication of Off-Axis Parabolic Mirrors at Thorlabs
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After initial fabrication, all of our off-axis parabolic mirrors are finished on our single-point diamond turning machine. Visit our Custom Mirrors tab for more information.
Mounting Features on Off-Axis Parabolic Mirror
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Base View of Hole Parallel to Collimated Beam
Engraved Part Number on Back of Off-Axis Parabolic Mirror
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Back View of Hole Parallel to Focused Beam
Optical Coatings and Substrates
Optic Cleaning Tutorial

Features

  • Centered Hole for Through Beam
  • Two Hole Orientations Available
    • Parallel to Focused Beam: Ø8 mm Entrance Hole in Back Tapers Down to Ø3 mm Hole in Mirror Surface
    • Parallel to Collimated Beam: Ø3.2 mm Hole from the Mirror Surface to the Flat Base
  • Reflected Beam is Focused without Spherical or Chromatic Aberrations
  • Unprotected Gold Coating Provides >97% Average Reflectance from 800 nm to 20 µm
  • Reflected Focal Lengths: 2", 4", 6", or 9" (50.8 mm, 101.6 mm, 152.4 mm, or 228.6 mm)
  • Surface Roughness: <100 Å (RMS)
  • Three Kinds of Mounting Adapters for Ø2" Mirrors with Holes Parallel to Focused Beam:
    • Externally SM-Threaded
    • Unthreaded for Use in Mirror Mounts
    • With 8-32 (M4) Taps for Post Mounting
  • Custom Off-Axis Parabolic Mirrors with Holes Available (Contact Tech Support)

Thorlabs' Off-Axis Parabolic (OAP) Mirrors with Holes are designed for applications that require two beams to propagate collinearly through space. Each mirror’s reflective surface can achromatically focus a collimated beam or collimate a point source, while the off-axis design separates the focal point from the rest of the beam path. Two hole orientations are available: parallel to the focused beam or parallel to the collimated beam.

Mirrors with holes that allow a through beam to be combined with a focused reflected beam are denoted by item #s that include an “H.” The Ø8 mm hole in the back of the substrate tapers down to a Ø3 mm hole as it approaches the mirror surface, permitting the through beam to be focused by a lens as it propagates. These mirrors are often used in electro-optic sampling measurements and other pump-probe experiments, such as time-resolved terahertz spectroscopy (TRTS). In these experiments, it is necessary to illuminate the electro-optic crystal with a pump beam passing through the parabola so that it overlaps with the focus of the THz probe beam that is reflected off of the surface of the parabola.

Mirrors with holes that allow a through beam to be combined with a collimated reflected beam are denoted by item #s that include a “V.” The Ø3.2 mm bore is large enough to accept a beam from our HeNe lasers. Due to the hole passing through the base of the part as seen int he image to the far right, these mirrors cannot be used with any of our OAP mirror mounting adapters. Instead, our smooth bore mounting adapters can be used to mount these parts.

As with the rest of our off-axis parabolas, these are first-surface mirrors which are segments of a parent paraboloid. They achromatically focus a collimated beam, and their reflective design eliminates phase delays and absorption losses introduced by transmissive optics. This makes them well suited for use with femtosecond pulsed lasers. The angle between the focused beam and the collimated beam (off-axis angle) is 90°. As shown in the diagrams above, the collimated beam should be normal to the base of the substrate to achieve a proper focus. The diamond-turned parabolic surface has an unprotected gold coating which provides >97% average reflectance from 800 nm - 20 µm (see the Graphs tab for a plot of the coating performance). Unprotected gold offers higher reflectance than protected gold but is more delicate. Additionally, these mirrors can be used in applications where the polarization state needs to be strictly maintained or to prevent dispersion due to the overcoat of protected gold mirrors.

The OAP mirrors are fabricated using aluminum substrates. The base of each mirror has three tapped mounting holes in a triangle pattern and an alignment hole. For OAP mirrors with holes parallel to the focused beam, the holes in the base can be used with a mounting adapter (see the Mounting Adapters tab for more details). Holes parallel to the collimated beam pass through the base of the OAP mirror, so mounting adapters cannot be used with these parts. The non-optical surfaces are black-anodized and laser-engraved with the item number for easy identification as shown in the image to the right. The interiors of both types of through holes are not anodized.

Care and Handling
The gold layer on unprotected mirrors does not include a protective overcoat. Bare gold does not oxidize in air, but can be easily damaged by fingerprints, aerosols, or the slightest contact with any abrasive material. Unprotected gold mirrors should only be handled when necessary and always held by the sides. Latex gloves or a similar protective covering should be worn to prevent oil from fingers from reaching the surface. No attempt should be made to clean the surface other than blowing off dust with clean, dry air or nitrogen. Any other cleaning method may damage the surface.

Off-Axis Parabolic Mirrors Selection Guidea
Mirror Coating
(See Graphs Tab
for Reflectance)
Wavelength
Range

90° Off-Axis

15°, 30°, 45°, 60° Off-Axis

90°, Hole Parallel to
 Focused Beam

90°, Hole Parallel to
Collimated Beam
UV-Enhanced Aluminum 250 nm - 450 nm Customa
Protected Aluminum 450 nm - 20 µm
Protected Silver 450 nm - 20 µm Customa
Protected Gold 800 nm - 20 µm
Unprotected Gold 800 nm - 20 µm Customa
  • We can manufacture off-axis parabolic mirrors with a variety of coatings, features, and off-axis angles. To request a quote for a custom mirror, please contact Tech Support.
Common Specifications
Metallic Coating Unprotected Gold
Reflectance (Average) >97% from 800 nm to 20 µm
Off-Axis Angle 90°
Clear Aperture >90% of Diametera, Not Including Hole
Surface Roughness (RMS)  <100 Å
Surface Quality  40-20 Scratch-Dig
Parent Focal Length Tolerance ±1%
Reflected Focal Length Tolerance ±1%
Mounting Holesb 8-32 Taps in Radial Pattern (3 Places)
Substrate Aluminum
Manufacturing Process Diamond Turned
  • The diameter is defined in the drawing below.
  • The OAP mirrors with holes parallel to the focused beam can be mounted to the adapters sold below using these holes. Our adapters will block the hole on the OAP mirrors with holes parallel to the collimated beam.
Item # Diametera Thicknessa RFLa,b PFLa,c Hole
Orientationa
Hole Diametera Reflected Wavefront Error (RMS)
MPD229H-M03 2" (50.8 mm) 2.47" (62.8 mm) 2" (50.8 mm) 1" (25.4 mm) Parallel to
Focused Beam
3 mm on Coated Surface
8 mm on Back of Substrate
<λ/2 at 633 nm
MPD249H-M03 2" (50.8 mm) 2.47" (62.8 mm) 4" (101.6 mm) 2" (50.8 mm) <λ/4 at 633 nm
MPD269V-M03 2" (50.8 mm) 2.47" (62.8 mm) 6" (152.4 mm) 3" (76.2 mm) Parallel to
Collimated Beam
3.2 mm
MPD399H-M03 3" (76.2 mm) 3.47" (88.2 mm) 9" (228.6 mm) 4.50" (114.3 mm) Parallel to
Focused Beam
3 mm on Coated Surface
8 mm on Back of Substrate
<λ/2 at 633 nm
  • The drawings below define the quantities in this table.
  • Reflected Focal Length
  • Parent Focal Length

The shaded region in the graph below denotes the ranges over which we guarantee the specified reflectance. Please note that the reflectance outside of this band is typical and can vary from lot to lot, especially in out-of-band regions where the reflectance is fluctuating or sloped.

Unprotected Gold -M03
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Excel Spreadsheet with Raw Data for -M03 Coating at 45° AOI



Excel Spreadsheet with Raw Data for Our Metallic Coatings
Parabolic Mirror Mounting Adapter Installation
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Mounting Adapter Installation

Mounting Adapters
The bottom of each off-axis parabolic mirror contains three tapped mounting holes in a triangle pattern and an alignment hole. These holes are used to attach our Mounting Adapters, which contain three corresponding counterbores and an alignment pin. Together, these features allow our OAP mirrors to be securely mounted to our extensive selection of optomechanical components. The tapped holes are also useful in OEM applications.

For our Ø2" OAP mirrors*, we offer three types of mounting plates. The first type is designed to be mounted in any Ø3" mirror mount. The second type, designed for post mounting, contains an 8-32 (M4) tapped hole on all four sides for direct mechanical compatibility with Ø1/2" Posts. The third type is externally SM2-threaded for direct compatibility with any internally SM2-threaded components, such as our rotation mounts.

Our Ø2" OAP mirrors can also be adapted to our SM threads by placing them into our SM Thread to Double Bore Adapters. This adapter allows rotation of the OAP mirror with respect to the adapter prior to securing its position, whereas when using the SM-threaded adapters offered on this page, the final location of the OAP mirror is dictated either by the threads themselves (when fully threaded into a mount) or by using the provided retaining ring to secure it in place.

We do not currently offer a mounting adapter for the Ø3" OAP mirror. However, it can be directly mounted in our KS3 Precision Kinematic Mirror Mount.

*Please note that these mounting adapters cannot be used with OAP mirrors with holes parallel to the collimated beam due to the hole passing through the base of the mirror. Smooth bore mounting adapters can be used to mount these parts.

Selecting a Mirror Based on Desired Output Beam Diameter

When using an off-axis parabolic mirror to collimate a point source, selection of the appropriate mirror is often done based on the desired output beam diameter. Beam diameter can be calculated very easily using the divergence half-angle of the incident light (Θ) and the reflected focal length of the OAP. To calculate the beam diameter in the small angle approximation, use the following equation:

Beam Diameter = 2 x sin(Θ) x Reflected Focal Length

If you are collimating from a fiber, the equation can be rewritten as:

Beam Diameter = 2 x NA (Fiber) x Reflected Focal Length

The table below lists the output beam diameter as a function of the reflected focal length of the mirror and the divergence half-angle of the incident light. Not listed here is the diameter of the OAP. The clear aperture of the OAP you select should be larger than the desired beam output diameter.

Reflected Focal Length Beam Diameter
  2.5° Source Divergence 5° Source Divergence 7.5° Source Divergence 10° Source Divergence
2" (50.8 mm) 4.4 mm 8.9 mm 13.3 mm 17.6 mm
4" (101.6 mm) 8.9 mm 17.7 mm 26.5 mm 35.3 mm
6" (152.4 mm) 13.3 mm 26.6 mm 39.8 mm 52.9 mm
9" (228.6 mm) 19.9 mm 39.8 mm 59.7 mm 79.4 mma
  • Please note that this diameter exceeds the clear aperture of our Ø3" parabolic mirrors.

Custom Off-Axis Parabolic (OAP) and Aspheric Mirrors

Key Capabilities

  • Nanotech® 450UPL Ultra Precision 3-Axis CNC Diamond Turning Lathe for Individual Custom Mirrors
  • Custom Sizes, Focal Lengths, Substrates, Coatings, and Clearance Holes
  • Off- and On-Axis Parabolic, Conical, and Toroidal Mirrors
  • Biconic Surfaces and Irregular Aspheric Optics

Thorlabs' advanced single-point diamond turning capabilities allow us to produce custom OAP and aspheric mirrors in small quantities. We can produce long focal length and large diameter optics, as well as optics with custom shapes.
Toroidal Mirror
Click to Enlarge

We offer OAP mirrors with custom sizes, focal lengths, substrates, coatings, and clearance holes.

In addition to our stock off-axis parabolic (OAP) mirrors, Thorlabs is also capable of manufacturing a variety of custom aspheric mirrors. Our unique single-point diamond turning (SPDT) capabilities allow us to produce these customs in low quantities at prices that are comparable with our stock offerings. As shown in the video to the right, we engage the slow-slide-servo process of our SPDT machine to polish individual off-axis mirrors by synchronizing the rotational position of the spindle with the linear position of the translation axes.

Toroidal Mirror
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Toroidal mirrors have two different radii of curvature and are used to image off-axis points without introducing astigmatism.
Conical Mirror
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Conical mirrors provide 360° of illumination.

This unique manufacturing capability allows us to provide OAP mirrors with custom reflected focal lengths and diameters, including long-focal-length and large-diameter optics that cannot be produced by conventional two-axis machining. In addition, we can produce OAP mirrors with a variety of custom substrates (including copper), custom coatings, and custom hole sizes and shapes. The use of copper substrates and other advanced techniques also allow us to offer OAP mirrors with enhanced finishes that exhibit less surface roughness than our our stock products, resulting in improved wavefront quality.

Our SPDT competency also enables us to produce mirrors with other custom biconic surfaces and aspheric shapes, including on-axis parabolic, conical, and toroidal mirrors. These custom mirror shapes can be used in a wide variety of optical instruments and specialized imaging systems. For example, toroidal mirrors, which are used to image off-axis points without introducing astigmatism, are commonly used in compact Czerny-Turner monochromators. Conical mirrors, on the other hand, are ideal for non-imaging applications that require 360° of uniform illumination.

We are generally able to produce custom OAP mirrors and aspheric mirrors with short lead times. For modifications to an existing part, delivery in 4-6 weeks is standard. For custom shapes and long focal length optics, a 6-8 week lead time is typical. To receive more information or a quote for a custom optic, please contact Tech Support.

Our engineers are available to help manufacture optics for your application.

Customs are available in low quantities at prices that are comparable with our stock catalog products.
Please contact techsupport@thorlabs.com with your custom optic requests.


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Ø2" 90° Off-Axis Parabolic Mirrors with Through Holes

Off-Axis Parabolic Mirror in Post-Mounting Adapter
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Ø2" Unprotected Gold OAP Mirror on a MP508P2 Threaded Adapter Plate
Item # MPD229H-M03 MPD249H-M03 MPD269V-M03
Diametera 2" (50.8 mm) 2" (50.8 mm) 2" (50.8 mm)
Reflected Focal Length (RFL)a 2" (50.8 mm) 4" (101.6 mm) 6" (152.4 mm)
Parent Focal Lengtha 1" (25.4 mm) 2" (50.8 mm) 3" (76.2 mm)
Hole Orientation Parallel to Focused Beam Parallel to Collimated Beamb
Hole Diameter 3 mm on Coated Surface
8 mm on Back of Substrate
0.13" (3.2 mm)
Thicknessa 2.47" (62.8 mm)
Off-Axis Angle 90°
Reflected Wavefront Error <λ/2 at 633 nm <λ/4 at 633 nm
Base Mounting Holes Three 8-32 Tapsc Three 8-32 Tapsb
  • The diagram in the Specs tab defines these quantities.
  • Mirrors with holes through the base are not compatible with the mounting adapters sold below.
  • See below for the corresponding mounting adapters.

Care and Handling
The gold layer on unprotected mirrors does not include a protective overcoat. Bare gold does not oxidize in air, but can be easily damaged by fingerprints, aerosols, or the slightest contact with any abrasive material. Unprotected gold mirrors should only be handled when necessary and always held by the sides. Latex gloves or a similar protective covering should be worn to prevent oil from fingers from reaching the surface. No attempt should be made to clean the surface other than blowing off dust with clean, dry air or nitrogen. Any other cleaning method may damage the surface.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
MPD229H-M03 Support Documentation
MPD229H-M03NEW!Customer Inspired! Ø2" 90° Off-Axis Parabolic Mirror with Ø3 mm Hole Parallel to Focused Beam, Unprot. Gold, RFL = 2"
$333.54
Today
MPD249H-M03 Support Documentation
MPD249H-M03Customer Inspired! Ø2" 90° Off-Axis Parabolic Mirror with Ø3 mm Hole Parallel to Focused Beam, Unprot. Gold, RFL = 4"
$333.54
Today
MPD269V-M03 Support Documentation
MPD269V-M03NEW!Customer Inspired! Ø2" 90° Off-Axis Parabolic Mirror with Ø3.2 mm Hole Parallel to Collimated Beam, Unprot. Gold, RFL = 6"
$333.54
Today

Ø3" 90° Off-Axis Parabolic Mirror with Through Hole

Mirror in Mount
Click to Enlarge

Ø3" Unprotected Gold OAP Mirror in KS3 Mirror Mount
Item # MPD399H-M03
Diametera 3" (76.2 mm)
Reflected Focal Length (RFL)a 9" (228.6 mm)
Parent Focal Lengtha 4.50" (114.3 mm)
Hole Orientation Parallel to Focused Beam
Hole Diameter 3 mm on Coated Surface
8 mm on Back of Substrate
Thicknessa 3.47" (88.2 mm)
Off-Axis Angle 90°
Reflected Wavefront Error <λ/2 at 633 nm
Base Mounting Holesb Three 8-32 Taps
  • The diagram in the Specs tab defines these quantities.
  • See below for the corresponding mounting adapters.

Care and Handling
The gold layer on unprotected mirrors does not include a protective overcoat. Bare gold does not oxidize in air, but can be easily damaged by fingerprints, aerosols, or the slightest contact with any abrasive material. Unprotected gold mirrors should only be handled when necessary and always held by the sides. Latex gloves or a similar protective covering should be worn to prevent oil from fingers from reaching the surface. No attempt should be made to clean the surface other than blowing off dust with clean, dry air or nitrogen. Any other cleaning method may damage the surface.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
MPD399H-M03 Support Documentation
MPD399H-M03Customer Inspired! Ø3" 90° Off-Axis Parabolic Mirror with Ø3 mm Hole Parallel to Focused Beam, Unprot. Gold, RFL = 9"
$676.26
Today

Ø2" Off-Axis Parabolic Mirror Mounting Adapters

Off-Axis Parabolic Mounted on Post using MP508P2 Adapter
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Ø2" OAP Mirror with Hole Parallel to Focused Beam Mounted on a Ø1/2" Post
Using an MP508P2 Adapter
OAP Mirror with MP254P1 Adapter Mounted in Kinematic Mirror Mount
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Ø2" OAP Mirror in KS3 Mirror Mount Using an
MP508P1 Adapter
OAP Mirror Mounted in Cage System using SM2MP Adapter
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Ø2" OAP Mirror Threaded into a KC2-T Cage Mount Using an
SM2MP Adapter
  • Contains Three #8 Counterbores and an Alignment Pin for Mounting to OAP Mirrors
  • SM2MP: Diameter is Externally SM2 Threaded
  • MP508P1: Designed to Fit into Ø3" Mirror Mounts
  • MP508P2(/M): Post Mountable in Four Orientations

Our Mounting Adapters for Ø2" Off-Axis Parabolic Mirrors provide mounting alternatives to our smooth bore kinematic mirror mounts. Each contains three #8 counterbores that are positioned to align with the 8-32 tapped holes on our Ø2" OAP Mirrors. Please note that these adapters will block the through holes on OAP Mirrors with holes parallel to the collimated beam. Our smooth bore mounting adapters can be used to mount these parts.

SM2MP
The SM2MP OAP Mirror Adapter is externally SM2 threaded (2.035"-40), which allows a Ø2" OAP mirror to be directly mounted to an internally SM2-threaded component. The adapter is designed to allow easy adaptability to a 60 mm cage system as well as SM2-threaded mirror, translation, and rotation mounts. The included SM2RR retaining ring secures the adapter in place when it is threaded into a mount. An SPW604 and SPW801 Spanner Wrench can be used to thread the retaining ring and adapter, respectively. Three low profile 8-32 cap screws and the required 5/64" hex key are provided with each adapter.

MP508P1
The unthreaded MP508P1 OAP Mirror Adapter is sized to fit inside a Ø3" mirror mount, such as the KS3 Mirror Mount shown above. Three standard 8-32 cap screws and the required 9/64" hex key are provided with each adapter.

MP508P2(/M)
The MP508P2(/M) OAP Mirror Adapter contains four 8-32 (M4) taps, for post mounting, that orient the OAP mirror at right angles. The distance from the center of the optic to the edge of the mount in the MP508P2 is 1.5" (38.1 mm), allowing for standardized optical axis heights when used with a fixed height post, such as our Ø1" Posts. Please note that the MP508P2(/M) is not compatible with Ø3" mirror mounts, and is instead designed for post mounting. Three standard 8-32 cap screws and the required 9/64" hex key are provided with each adapter.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
MP508P2 Support Documentation
MP508P28-32-Threaded Adapter for Ø2" Off-Axis Parabolic Mirrors
$33.41
Today
+1 Qty Docs Part Number - Universal Price Available
SM2MP Support Documentation
SM2MPExternally SM2-Threaded Adapter for Ø2" Off-Axis Parabolic Mirrors
$35.45
Today
MP508P1 Support Documentation
MP508P13" Outer Diameter Adapter for Ø2" Off-Axis Parabolic Mirrors
$31.37
Today
+1 Qty Docs Part Number - Metric Price Available
MP508P2/M Support Documentation
MP508P2/MM4-Threaded Adapter for Ø2" Off-Axis Parabolic Mirrors
$33.41
Today
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