OSLO Familiarization

ECEn 466 Introduction to Optical Engineering

425 CB

Laboratory objective:

Familiarize yourself with the optical design package OSLO. The student version of the package is loaded on the CAEDM machines. Use the lens design package to input different lenses and get an estimate on their quality.

Preliminary

  1. Calculate the radius of curvature for a plano convex lens (PCX) such that it has a focal length of f=100mm. Use the thin lens equation. Use the glass called BK7. This glass is the most common used for lenses. Use a wavelength in the middle of the visible spectrum (=550nm).
  1. Find a PCX lens in the Edmund Scientific catalog ( with a diameter of D=50mm and a focal length of f=100mm. List out the catalog number and the lens parameters including diameter, effective focal length, back focal length, center thickness, radius of curvature, and the material.
  1. Explain what the following parameters are: effective focal length, back focal length, and center thickness.
  1. Calculate the radius of curvature for a double convex lens (DCX) such that it has a focal length of f=100mm. Use the thin lens equation. Use the glass called BK7. This glass is the most common used for lenses. Use a wavelength in the middle of the visible spectrum (=550nm).
  1. Find a DCX lens in the Edmund Scientific catalog ( with a diameter of D=50mm and a focal length of f=100mm. List out the catalog number and the lens parameters including the material.
  1. Find an achromatic ACH lens in the Edmund Scientific catalog ( with a diameter of D=50mm and a focal length of f=100mm. List out the catalog number and the lens parameters including the material.
  1. Calculate the focal length of the ACH lens using the thin lens formula. The thin lens equation for a lens with three surfaces is given by . See the following picture for the achromatic doublet.
  1. Go through the OSLO tutorial to learn how to input lenses and plot a simple ray trace. This should be through around page 6 of the tutorial.

Table 1. Indices of Refraction for common materials

Material / n (=400) / n (=550) / n (=700)
BK7 / 1.5308 / 1.5185 / 1.5131
BaF10 / 1.6961 / 1.6731 / 1.6637
SF10 / 1.7782 / 1.7337 / 1.7173
SF5 / 1.7126 / 1.6771 / 1.6637

Laboratory

  1. Input the PCX lens into OSLO and save it. Make the flat surface of the lens as the first lens surface. Be sure to include the following:
  2. The lens surfaces
  3. The glass type
  4. The lens aperture radius (it should be 25mm)
  5. Set the wavelengths of (400nm, 550nm, 700nm)
  6. Only on-axis fields
  7. Set the entrance pupil diameter to 50mm.
  8. With a wavelength of =550nm make the thickness of the last surface of the lens such that the image has the smallest size. Plot out the lens drawing. Label the following parameters on the diagram.
  9. Effective focal length (EFL)
  10. Back focal length (BFL)
  11. Center thickness (CT)
  12. Edge thickness (ET)
  1. For each of the wavelengths find the best focus to within 1mm. Plot the spot diagram and list out the RMS spot size. Use the spot diagram to perform this step. Be sure that you only have one wavelength set.
  2. Find the best focus including all of the wavelengths. Plot the spot diagram and list out the RMS spot size.
  3. Compare the lens with the lens calculated in the preliminary.
  4. The spot diagram lists the diffraction limited spot size. Reduce the entrance pupil diameter until the geometrical RMS size is less than the diffraction limited size. This should be done with only =550nm.
  1. Repeat steps 1-6 for the PCX lens with curved surface of the lens as the first lens surface. Why is it different than with the flat surface of the lens as the first surface?
  1. Repeat steps 1-6 for the DCX lens.
  1. Repeat steps 1-6 for the ACH lens.