Ruler V2:

Bi-Directional Variable Pitch Prism Array

Used to bend light to a specific angle. Note the coarse and fine prism arrays incorporated into one optical element. This Variable Pitch Prism Array demonstrates only a small selection of possible groove spacings.


Dimensions: 40 mm x 18 mm
Pitch Range: 0.065 to 0.640 mm
Pitch Increment: 0.005 mm
Prism Angle: 90°
Tilt of Prism Facets Along +45° Diagonal: 30°
Tilt of Prism Facets Along -45° Diagonal: 45°

Spiral Microlens Array

Designed to demonstrate the relationship between dispersion angle and lenslet aperture size. Lenslet aperture diameter increases radially along a logarithmic spiral from about .247mm to 2.554mm. Each lenslet center is placed at golden angle increments (~137.5 degrees) along the spiral. The lenslet radius is 1.277mm, and the radius of curvature is the same for all 197 lenslets.

Use a laser pointer to show that the smaller lenslet apertures spread light less than the larger apertures.


The Zernike lens in Ruler v2 is highly exaggerated for ease of visualizing characteristics. Zernike optics can be specifically designed as inverse, non-rotationally symmetric corrector plates to correct known aberrations in optical systems.

Spherical Vs. Aspherical

Place these lenses 5.5mm above the grid on the back of the blue ruler sleeve to contrast the behavior of spherical and aspherical lenses. Note the image through the spherical lens is distorted and that the asphere's is not. These are f/ 1.5 lenses with an effective focal length (EFL) of 12.0 mm at Na d-line.

View all four rulers
IMG_5973 - main ruler 2 image_edit
IMG_5957 - prism array_edit
IMG_5893 - spiral microlens array_edit
DSCN0681 - zernike surface_edit
20220118_165105 - sphere and asphere_edit