Off-Axis Parabolic Mirrors with Through Holes
Through Hole orientation can be designed for parallel to focused beam or parallel to collimated beam.
Off-Axis Parabolic Mirrors without Through Holes

Off-Axis Parabolic (OAP) Mirrors

Aluminum 6061-T

Surface Flatness:
<1 λ or customized

Off-Axis Angle:
90° or customized

Protected Aluminum
Protected Silver
Protected Gold

1”, 2”, 3”, 4”, large size up to 600mm


Non-optical surface:
Black Anodized


Off-Axis Parabolic (OAP) Mirrors are mirrors whose reflective surfaces are segments of a parent paraboloid. They achromatically focus a collimated beam or collimate a divergent source, and their off-axis design separates the focal point from the rest of the beam path. The reflective design eliminates phase delays and absorption losses introduced by transmissive optics.
Blank OAP Mirrors
              Different Shape of OAP Mirrors


wdt_ID Attributes Values


  •  Material: Aluminum 6061-T6
  • Dimensions
    SZLASER  provide the standard OAP with 1 inch(25.4mm), 2 inches(50.8mm), 3 inches(76.2mm), 4 inches(101.6). Large sizes can be up to 600mm
  • Reflective Focal Length
    The RFL of standard OAP is 1 inch, 2 inches, 4 inches and 6 inches.
  • Off-axis angle
    Standard off-axis angle is 90°, others can be customized.
  • Coating
    Protected Aluminum(400-2000nm)
    Ravg >85% @ 400 – 700nm Ravg >90% @ 400 – 2000nm
    Protected Silver(450nm – 2000nm)
    Ravg >98% @ 450 – 2000nm Ravg >98% @ 2000 – 10,000nm
    Protected Gold(700nm – 2000nm)
    Ravg >96% @ 700 – 2000nm Ravg >96% @ 2000 – 10,000nm
    Bare Gold, UV Enhanced Aluminum is also available.
  • Alignment Through Holes
    Standard OAP’s through holes diameter is 3mm. Through Hole orientation can be designed for parallel to focused beam or parallel to collimated beam.
  • Surface roughness: <150 Å (RMS), customizable up to <20 Å (RMS)


Off axis parabolic mirror (OAP) is one of the common components to build terahertz and infrared light paths. Based on the principle of geometry paraboloid, off-axis mirror can focus the collimated beam / collimated THz wave with parallel incidence to the focus, and can also convert the terahertz wave or infrared light emitted by point light source into parallel transmission beam.
Main applications of off-axis parabolic mirrors are as follows:
  • Target simulators
  • Collimators
  • MTF measuring systems and other optics test devices
  • Spectroscopic and FTIR systems
  • Radiometers
  • Beam expanders
  • Laser divergence measuring systems
Use of off-axis optics allows optical engineers to achieve the following advantages
  • Minimize system sizes
  • Minimize system weight
  • Both “wedged” and equi-thick mirrors are available
  • Minimize system cost


Related Resource for reference

OAP mirrors relay microscope for experiments with ultra-cold matter
A new optical system is introduced for the imaging of Coulomb crystals held in a cryogenic ion trap where there are space limitations preventing the placement of an objective close to the fluorescing ions. The optical system features an off-axis parabolic (OAP) mirror relay microscope that will serve to acquire images of a lattice of fluorescing ions confined within an ultra-high-vacuum vessel operating at temperatures below 10 K. We report that the OAP mirror relay setup can resolve features smaller than the separation between neighboring ions in Coulomb crystals. The setup presented here consists of two 90-degree OAP mirrors arranged into a relay from which standard microscope optics deliver the image to a camera. This design allows the first element in the imaging setup—an OAP mirror—to be located as close as possible to the ion trap, achieving high resolution without the need for a direct line-of-sight to the trap center or for a view port to be located in close proximity to the ion trap. Such an arrangement would not be possible with a standard microscope objective, which is the approach commonly adopted by the field. OAP mirrors represent a novel solution for delivering polychromatic images with micrometer-scale resolution over extended distances.
Click to view the full article
Adjusting Methods of OAP Mirror in Terahertz Time Domain System
According to the geometric optics, off-axis parabolic mirrors are used in terahertz time domain system for focusing the terahertz pulse. Theoretically, the focus of the parabolic reflector to eliminate the effects of spherical aberration, but a very high sensitivity to its optical axis misalignment, subtle misalignment will reduce the focal spot quality and therefore the need for precision optical axis adjustment is important. This article discusses terahertz time-domain spectroscopy system adjustment method in four off-axis parabolic mirror, after many experiments have proved feasible. In this work, two optical path adjustment methods were analyzed. The first approach is based on adjustment of spot shape from collimation and focus. In the second method, depend on the principle that the incident light path is different from reflected light path in parabolic cross section. Through testing this two methods have been proved feasible.
Click to view the full article
Alignment of an OAP mirrors with two parallel He-Ne laser beams
Two parallel laser beams are used to align an off-axis parabolic mirror without alignment telescope and reference flat. In this method the optical axis of an off-axis parabolic mirror is made parallel to the incident laser beams, in the plane of incidence, by measuring directions of the reflected beams and by changing height and orientation of the mirror. Then, the focal point ofthe off-axis parabolic mirror is automatically found where the two reflected beams cross each other. The alignment of the optical axis to the incident beams is done without knowing focal length and off-axis distance of the mirror. Alignment sensitivity is derived both numerically and analytically. When focal length is 457 mm, off-axis distance is 127 mm, and diameter is 178 mm, the off-axis parabolic mirror is aligned to the incident beams with an angular error of less than 3 mrad.
Click to view the full article
OAP fundamentals
A parabolic mirror takes light from a point source located at the focus and creates a collimated beam. In other words, a source with spherical wavefronts placed at the parabolic focus is converted into a beam with plane wavefronts. The reverse operation is also true; plane wavefronts incident on the parabolic mirror are focused at the focal point. This is a valuable tool for optical design because the single surface of an OAP can produce a diffraction limited image without chromatic effects. A complete parabolic mirror would focus a collimated beam at its focal point, which is often not useful because it overlaps with part of the incoming beam. Accessing the focal point can be difficult and even impossible without obstructing part of the incoming beam. However, if only a portion of the parabolic surface is used, the beam will focus off-axis at a more accessible location, as shown in Figure 1.
Click to download the full file 521_Tutorial_Off-Axis Parabolic (OAP) Mirrors


Related Products

Related Products

Integral Mirrors
Step Mirrors
Micro Structure Parts
Polarization Beamsplitter Cubes