The “off-axis parabolic mirror” suitable for applications such as femtosecond lasers, infrared, and terahertz.

Off-axis parabolic mirrors (OAP) are segments of a parabolic mirror that are offset from the symmetric center of the parabolic surface. These mirrors are commonly used components in constructing terahertz and infrared optical paths. Based on the principles of geometric parabolas, they can focus collimated incident beams or collimated THz waves to a focal point. Additionally, they can convert terahertz waves or infrared light emitted from a point source into collimated beams for parallel transmission.

Off-axis parabolic mirrors have the ability to focus collimated light without introducing spherical aberration. When a collimated beam is incident perpendicularly to the base of the mirror, the reflected light converges at the focal point. By placing a point source at the focal point, a collimated beam can be obtained. The angle between the focused beam and the collimated beam is known as the off-axis angle. By selecting different sections of the parent parabolic surface, off-axis parabolic mirrors with various off-axis angles can be obtained.The substrate material of off-axis parabolic mirrors is typically aluminum, and their surfaces are machined using precision metal tools. As a result, these mirrors operate based on the principle of reflection, which eliminates the phase delay and absorption losses associated with transmissive optical elements. The surface roughness of off-axis mirrors significantly impacts their performance, and they usually feature surface roughness values of <50Å or <100Å RMS.

Off-axis parabolic mirrors are widely used in various fields, including astronomical observation optical devices, spectroscopic detection, astronomical telescope systems, sighting devices, beam expanders, infrared systems, solar concentrator systems, projection systems, and emission/detection equipment. Compared to lenses, off-axis parabolic mirrors do not produce spherical aberration or chromatic aberration, and they do not introduce phase delay or absorption losses. This makes them particularly suitable for applications involving femtosecond lasers, infrared, and terahertz technologies.