Off-Axis Parabolic Mirrors and Their Characteristics
An off-axis parabolic mirror is a specialized optical mirror cut from a larger parabolic mirror. Parabolic mirrors collimate light, and an off-axis parabolic (OAP) mirror will do the same, and can also focus incident collimated light to a point. OAP mirrors are smaller than parabolic mirrors and are easier to incorporate into complex optical systems with minimal obstruction. Their small footprint and unique shape causes the mirror’s focal point to be readily accessible.
By definition, an OAP mirror is cut from the parent parabola at an off-axis: it is not centered on the parent’s optical axis. Because of this, the optical axis of the derivative mirror will be displaced from the optical axis of the parabolic mirror. The focal point, however, will be the same.
Off-set angle: The angle between the optical axis and the direction of the incoming or outgoing light beam in an off-axis parabolic mirror.
Parent focal length: The focal length of the ideal on-axis parabolic mirror with the same shape as the off-axis mirror.
Effective focal length: The actual focal length of the off-axis parabolic mirror, accounting for the offset angle and deviation from the ideal configuration.
Choosing an Off-Axis Parabolic Mirror
Key parameters of an off-axis parabolic mirror are the off-axis angle (OAA), the off-axis distance (OAD), and the focal length.
Choose an appropriate OAP mirror by deriving the desired reflected focal length from your desired beam diameter. The small angle approximation leads to a very simple relationship between these two parameters:
Beam Diameter = 2 x sin(Θ) x Reflected Focal Length
Where Θ is the divergent half-angle of the incident light. In fiber optics, when collimating from an optical fiber, you may replace sin(Θ) by NA (fiber).
| Avantier Inc. | |
|---|---|
| Product Category | Optical Mirrors |
| Product Name | Off-Axis Parabolic Mirror |
| Mirror Types | Parabolic Mirror |
