Chapter 3. Introduction to Zemax. 3.1 Introduction. 3.2 Zemax

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$Chapter 3 Introduction to Zemax 3.1 Introduction Ray tracing is practical only for paraxial analysis. Computing aberrations and diffraction effects are time consuming.$

1 Chapter 3 Introduction to Zemax 3.1 Introduction Ray tracing is practical only for paraxial analysis. Computing aberrations and diffraction effects are time consuming. Optical Designers need some popular softwares (such as Zemax, Code V, TracePro, OSLO, etc.) which help characterize and optimize the design. In this course, we ll use Zemax 2009 and Zemax OpticStudio Zemax Zemax is software for the optical design. It is used to analyze imaging system like camera lenses, illumination system, etc. Today, Zemax company presents several products (See: OpticStudio (you can try free version) LensMechanix Zemax Virtual Prototyping Figure 3.1: The Zemax Layout for meridional rays. 8

2 CHAPTER 3. INTRODUCTION TO ZEMAX 9 Some feature of Zemax are as follows: Zemax is the first optical design software written for Windows systems and written by Ken Moore in (The name of the first version of program was Max and afterwards the name changed Zemax). Zemax works by ray tracing and modeling the propagation of rays via an optical system. It can model the effect of optical elements like simple lenses, aspheric lenses, mirrors and diffractive optical elements, Figure??. Zemax can produce standard analysis diagrams such as spot diagrams and ray-fan projects, Figure??. Zemax simulates coatings on optical surfaces. It can carry out standard sequential ray tracing via optical elements, nonsequential ray tracing for analysis of stray light, and physical optics beam propagation. Zemax has a tolerancing capability and thus makes it possible to analyze production and assembly faults. Zemax has optimization tools which can be used to maximize the performance and to minimize the deviations on developing the lens design by adjusting parameters. In application, Zemax is used in 1. Imaging Optics (Telescopes, Cameras) 2. Lighting and illumination (Free-form lenses, reflectors, Car headlights) 3. Laser and Fiber Optics design 3.3 Getting Started with Zemax In Squential Lens Design rays (from left to right) are traced from one surface to the next in the order in which they are listed. A ray starts at the object plane (OBJ) The ray is traced to surface 1, then to surface 2, and so on. A ray cannot skip a surface. e.g., not from 2 to 4. A ray cannot go back. e.g., from 3 to 1. A ray ends at the image plane (IMA)

CHAPTER 3. INTRODUCTION TO ZEMAX 10 3.3.1 Lens Data Editor (LDE) When you start Zemax, first you will encounter with Lens Data Editor where the majority of the lens data is entered.

3 CHAPTER 3. INTRODUCTION TO ZEMAX Lens Data Editor (LDE) When you start Zemax, first you will encounter with Lens Data Editor where the majority of the lens data is entered. LDE is a spreadsheet as shown in Figure 3.2. (If you close LDE accidentally, you can access the editor from Editors menu or by pressing Shift + F1) Figure 3.2: An empty lens data editor in Zemax. The description of some columns in LDE is as follows: Surf:Type The type of surface (Standard,Even Asphere, Diffraction Grating, etc). Comment An optional field for typing in surface specific comments. Radius Surface radius of curvature lens units Thickness The thickness (distance) in lens units separating the vertex of the current surface to the vertex of the following surface. Glass The material type (glass, air, mirror etc.) which separates the current surface and the next surface listed in LDE. Semi-Diameter The half-size of the surface (height of the surface) in lens units. Note that Lens units are the distance units in mm/cm/in/m. To change lens unit, press Gen button then goto Units Tab as shown in Figure 3.3. Reminder: 1 in = 2.54 cm = 25.4 mm.

CHAPTER 3. INTRODUCTION TO ZEMAX 11 Figure 3.3: Lens unit in Zemax. 3.3.2 Single Lens in Zemax We want to design a simple optical system which contains single lens Figure 3.

4 CHAPTER 3. INTRODUCTION TO ZEMAX 11 Figure 3.3: Lens unit in Zemax Single Lens in Zemax We want to design a simple optical system which contains single lens Figure 3.4. Figure 3.4: Simple single lens design in Zemax. 1. Press Gen button to set Entrance Pupil Diameter (EnPD) in Aperture tab. Set Aperture Value = 25 mm.

CHAPTER 3. INTRODUCTION TO ZEMAX 12 Figure 3.

Press Wav button to set Wavelength. Set λ = 0.

5 CHAPTER 3. INTRODUCTION TO ZEMAX 12 Figure 3.5: Aperture tab. 2. Press Wav button to set Wavelength. Set λ = µm. (In Zemax Wavelength are measured in µm). Figure 3.6: Wavelength data. 3. Empty LDE (Press Sas button to save your work as lens1.zmx). Figure 3.7: Empty LDE.

CHAPTER 3. INTRODUCTION TO ZEMAX 13 4. Click on IMA in LDE, then press Insert key two times. Then, Fill LDE as in Figure 3.8. Figure 3.8: Filled LDE. 6.

Some of these plots are shown in Figure 3.9 respectively. Here: Lay = Layout (of the optical system in 2D). Spt = Spot Diagram (on the image plane).

6 CHAPTER 3. INTRODUCTION TO ZEMAX Click on IMA in LDE, then press Insert key two times. Then, Fill LDE as in Figure 3.8. Figure 3.8: Filled LDE. 6. Click on Lay, Spt, Pre, Ray and Opd buttons to analyze the optical performances of the system. Each window has its own Settings. Some of these plots are shown in Figure 3.9 respectively. Here: Lay = Layout (of the optical system in 2D). Spt = Spot Diagram (on the image plane). Pre = Prescription Data (summary data of the system). Ray = Ray Fan plot (aberrations as a function of pupil coordinate). Opd = Optical Path Difference (as a function of pupil coordinate). Figure 3.9: Some of the optical performance plots.

7 CHAPTER 3. INTRODUCTION TO ZEMAX Exercises 1. Write a MATLAB program to input radii (R 1 and R 2 ), index of refraction (n) and diameter (D) of a lens and output effective focal length, paraxial f-number, working f-number, edge thickness, volume and mass of the lens in air. (Assume that mass density of the lens is 2.55 cc.) 2. Consider a singlet negative-meniscus lens whose center thickness is 10 mm, aperture is 25 mm, and glass is K5. Using Zemax, calculate the effective focal length for an object at infinity (a) for λ = 532 nm, R 1 = 80 mm and R 2 = 60 mm (b) for λ = 600 nm, R 1 = 60 mm and R 2 = 80 mm 3. Consider a single positive bi-concave lens whose center thickness is 10 mm, aperture is 25.4 mm, and glass is BK7. For an object at infinity and wavelength λ = 1000 nm, and radii R1 = 100 mm and R2 = 80 mm. (a) What is the effective focal length of the lens? (b) What is the back focal length of the lens of the lens? (c) What is the Entrance pupil diameter of the lens? (d) What is the exit pupil diameter of the lens? (e) What is the edge thickness of the lens? 4. Two lenses in Zemax. Given: λ = 650 nm and entrance pupil diameter is 25 mm, Figure 3.10.(a) Implement the following geometry in Zemax LDE. (b) What are the back focal length and front focal length and effective focal length of the system? (c) What is the spot radius on the image plane? Figure 3.10: A simple doublet. 5. Three lenses in Zemax. Given the triplet prescription as illustrated in Figure For an object at infinity find the effective focal length of the system. [Note that for radius R, Curvature = C = 1/R and Power = φ = (n 1)/R.]

8 CHAPTER 3. INTRODUCTION TO ZEMAX 15 Figure 3.11: A simple triplet.

Sequential Ray Tracing. Lecture 2

Sequential Ray Tracing. Lecture 2 Sequential Ray Tracing Lecture 2 Sequential Ray Tracing Rays are traced through a pre-defined sequence of surfaces while travelling from the object surface to the image surface. Rays hit each surface once