PLX Hollow Roof MirrorsTM (HRMs) are ideal for redirecting light in one coordinate and any application where a roof top or Porro prism can be used. Useful in all wavelengths, they are available in different accuracies, coatings, and configurations.



  • For any application where a roof top or Porro prism can be used.
  • The optical path is in the air so there is no refraction or reflecting front prism surface.
  • Useful in all wavelengths and available in a variety of accuracies and coatings.
  • Light weight aluminum housing for protection and ease of handling.
  • Compatible with all major mounting systems.
  • Custom "Knife Edge" design option available upon request, enhances beam quality, eliminates the cause of obscuration.
  • RoHS Compliant.
  • PLX is a registered ISO 9001 company.

Coating Specification Chart

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Ideal for redirecting light in one coordinate.

The HRM is constructed from two first-surface mirrors assembled by a proprietary process to form an inside corner. This inside corner forms a 90-degree angle to a very high level of accuracy. The mirrors can be coated for optimization over a spectral range from UV to far IR. This configuration eliminates material absorption and chromatic aberration.

The HRM can be used in almost every application where a roof or porro prism can be used. Because the optical path is in air, there is no refraction nor any reflecting front prism surface. It is also insensitive to tilt or misalignment in one coordinate. If the HRM is rotated about the roofline, the reflected beam direction does not change. The HRM is provided in a versatile housing, which is compatible with all major mounting systems.

When ordering, be sure to add a suffix to the catalog number to indicate the desired mirror coating.

To view coating specifications, click the "Mirror Coating Spec." button on bottom of the chart. Example: RM-102-5A

Width is measured across the roof edge direction.

Length is measured along the roof edge direction.

Specification Chart
Model Clear Aperture
Width (in/mm)
Clear Aperture
Length (in/mm)
Mirror Surface
RM-051 RM-051 0.5/13 1.0/25 0.25 - 15.0 λ/10 - λ/4 70
RM-1005 RM-1005 1.0/25 0.5/13 0.25 - 15.0 λ/10 - λ/4 35
RM-101 RM-101 1.0/25 1.0/25 0.25 - 15.0 λ/10 - λ/4 90
RM-102 RM-102 1.0/25 2.0/51 0.25 - 15.0 λ/10 - λ/4 165
RM-104 RM-104 1.0/25 4.0/102 0.25 - 15.0 λ/6 - λ/4 250
RM-201 RM-201 2.0/51 1.0/25 0.25 - 15.0 λ/10 - λ/4 175
RM-202 RM-202 2.0/51 2.0/51 0.25 - 15.0 λ/10 - λ/4 285
RM-204 RM-204 2.0/51 4.0/102 0.25 - 15.0 λ/6 - λ/4 475
RM-303 RM-303 3.0/76 3.0/76 0.25 - 15.0 λ/8 - λ/4 825

If you don't see what you need above:
Also available are custom-made HRMRs complete to your specifications. Potential variations include: smaller and larger apertures; modified mounts to meet your interface; super-critical accuracies; dielectric mirror coatings for high-powered lasers; and units able to withstand military and space environments. Click here for a Custom Quote. Specify what your application is and our engineering staff will get back to you.