The meanings of the parameter indicators of the Corner Cube Prism

Analysis of the Meanings of Core Parameter Indicators of Corner Cube Prism

The Corner Cube Prism (also known as the straight corner cube prism or the backward reflection prism) is an optical component with three mutually perpendicular reflection surfaces that can reflect incident light back in its original direction. It is widely used in laser ranging, optical alignment, remote sensing mapping and other fields. The core parameters directly determine the optical performance. Here are the detailed meanings of the key indicators:

Ⅰ.Geometric accuracy parameters

1.90° perpendicularity error

It refers to the deviation of the actual Angle between the three reflective surfaces of a prism from the ideal 90°, measured in arcseconds (").

This is the core indicator of the cone prism, and the smaller the error, the higher the reverse parallelism of the incident light. Industrial-grade products typically ≤3 ", while high-precision rangefinder prisms can be controlled at ≤0.5 ".

2.Vertex eccentricity error

It refers to the offset of the intersection vertex of three reflective surfaces from the geometric center of the prism, measured in micrometers (μm).

Excessive eccentricity can cause the reflected beam to shift, affecting the accuracy of long-distance alignment. Generally, it is required to be ≤5μm.

3.Surface shape  accuracy

Describes the flatness of a single reflective surface in wavelength (λ, usually 632.8nm).

The higher the surface shape accuracy, the smaller the wavefront distortion of the reflected light, suitable for scenarios such as laser interference and high-precision ranging, with conventional indicators ranging from λ/10 to λ/20.

4.Surface roughness (Ra)

The degree of microscopic concavity and convexity of the reflective surface, measured in nanometers (nm).

Low roughness reduces light scattering loss, enhances reflection efficiency, and high-precision products require Ra≤1nm.

2. Optical performance parameters

1.Deviation of the backward reflection Angle

It refers to the deviation of the Angle between the emergent light and the incident light after the incident light is reflected by the prism, measured in arcseconds.

This indicator comprehensively reflects the influence of parameters such as perpendicularity and surface shape, and is a direct standard for measuring the reverse reflection ability of the prism, with quality products ≤2 "

2.Reflectance

It refers to the efficiency with which a prism reflects light in the target band, divided into total reflectiontype and coated reflection type.

Total reflection type: It relies on the critical Angle of the prism material to  achieve total reflection, suitable for specific bands, reflectance ≥99%;

Coated   reflective type: The surface is coated with a high-reflection film (such  as metal film, dielectric film), which can be adapted to the full band  from ultraviolet to infrared, with a reflectance of ≥99.5%.

Wavelength applicable range

Refers to the light band in which a prism can maintain stable optical performance, determined by the substrate material and the type of coating.

Fused silica:Compatible with 193nm to 2.5μm (UV to near-infrared);

Optical glass:Compatible with 400nm to 2μm (visible to near-infrared);

Infrared crystal materials (such as germanium, zinc selenide) : compatible with 2μm to 15μm (mid-infrared       band).

Ⅱ. Environmental Reliability parameters

Anti-laser damage threshold

It refers to the maximum laser power density that the prism surface can withstand, measured in J/cm² (pulsed laser) or W/cm² (continuous laser).

This indicator determines the lifespan of the prism in high-power laser systems, and the threshold for fused silica prisms in the 1064nm band is typically ≥10 J/cm² (10ns pulse).

Temperature adaptation range

It refers to the range of ambient temperatures within which the prism can function properly, determined by the coefficient of thermal expansion of the material.

Industrial-grade products are generally -40 ° C to 85 ° C, while aerospace remote sensing prisms can be extended to -60 ° C to 120 ° C.

Film adhesion

For coated prisms, measure the adhesion stability of the film layer under environmental changes (temperature, humidity), test standard reference MIL-C-675C ensures no delamination and no oxidation over long-term use.

Material Parameters

Base material

Common types include BK7 optical glass, fused quartz (JGS1/JGS2), calcium fluoride (CaF₂), etc. Different materials have different refractive indices, dispersion coefficients, and transmittance, and should be selected according to the application band.

Uniformity of  refractive index

It refers to the consistency of the refractive index of the material inside a prism, measured in ×10⁻⁶.

The better the uniformity, the smaller the wavefront distortion when light is transmitted. High-precision applications require ≤5×10⁻⁶.

Summary: 

The parameters of the Corner Cube Prism need to be matched according to the specific scenario - laser ranging prioritizingthe deviation of the backward reflection Angleandthe anti-laser damage threshold; The optical alignment criteria should focus onverticality errorsandvertex eccentricity. UltraOpto offers a full range of custom solutions to meet high precision requirements in various fields.

A comparison table of core parameters of Corner Cube Prism