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Index

Chapter 22 – Simulation of the alignment of a Cooke triplet using a Bessel beam reference

For some time, I wanted to simulate the assembly of a Cooke triplet using a Bessel beam as a reference,and assuming the hardware constrained the alignment of each element to either a tilt or decenter as isthe case for many precision lens assemblies. A new optical design software is now available that makesthis modelling relatively […]

Chapter 21 – Bessel Beam Alignment of a Single Lense

Introduction: In Chapters 14 and 15 I explained how a Bessel beam is used to align optics when you have all the necessary degrees of freedom to fully align the optics in tilt, decenter and focus. Many times, you have physical constraints due to the hardware the optics are installed in, so you don’t have […]

Chapter 20: Aligning Off-Axis Parabolas with a Bessel Beam — It’s Much Easier

Introduction In Chapter 18, I described aligning off-axis parabolas (OAPs) by placing the focus of a test instrument at the OAP’s focus and autoreflecting off a plane mirror. Although I suggested some tips to ease the process, the initial alignment—getting the reflected light back into the test device’s objective—remains challenging. Because I’ve found that using […]

Chapter 19 – Microscope Objective to Tube Lens Alignment

The subject of this Chapter is prompted by several questions over the last couple of months concerning the alignment of tube lenses to high power microscope objectives. In most microscopes these days the objectives are designed as finite to infinite conjugate optics so there is a need for a “tube” lens to focus the object […]

Chapter 18 – Alignment of Off-Axis Parabolas

Although this is a chapter on off-axis parabolas (OAPs), I want to start with one more way of testing symmetric parabolas because it illustrates a point about off-axis alignment. Assume we have a symmetric parabola with no central hole and we want to minimize the obstruction due to testing. If we set the parabola up […]

Chapter 17 – Alignment of Symmetric Parabolas

I often receive requests for assistance with aligning parabolic mirrors, particularly off-axis ones. Interestingly, with the right tools, the actual alignment process is often quicker than mounting the optical alignment equipment. This observation led me to reflect on the tools themselves. Currently, no traditional method—whether using an autocollimator or an alignment telescope—provides an effective way […]

Chapter 16 – Footnote for Chapters 14 and 15

This brief chapter serves as a vital addendum to the last two chapters. While I’ve already described the alignment process, I realized I hadn’t emphasized how remarkably simple it is—and what makes it so effortless. Over the years, countless methods have been used to align optics successfully, long before Bessel beams entered the picture. What […]

Chapter 15: Tabletop Alignment Part 2

In Chapter 14, we showed how to determine the axis of a laser beam to which we want to align optical elements and then how to align a Bessel beam to the laser beam axis. This Chapter shows the steps to align optical elements to the reference Bessel beam. With tabletop alignment, you have all […]

Chapter 14: Tabletop Alignment Part 1

At last, I am back to writing more about optical alignment. The hiatus was due to my realization that most readers are not interested in assembling lenses in a tube. Rather, they want to align free-standing optics on tabletops or benches in labs researching topics like laser light interactions with matter, free-space communication, and quantum […]

Chapter 13: New Optical Alignment Tools

In Chapter 12, I commented again on classical optical instruments since there was interest in an earlier discussion. This got me thinking about what had changed in optical technology since the period ending about 1950 when there was a rather canonical set of classical optical metrology tools. There has been a huge technological change since […]

Chapter 12: Further Comments on Classical Optical Instruments

There was more interest in Chapter 3 about the classical instruments used for optical alignment than any other chapter to date, and I didn’t have a chance to say all I wanted to, so I will continue the discussion in this Chapter to emphasize how changes in technology have changed the design of these instruments. […]

Chapter 11: Alignment and Precision Engineering

As I said in the first chapter, I hope to make these articles into a book on alignment after significant editing to organize the material coherently. In that spirit, and before I forget, let me discuss some aspects of alignment and precision engineering that belong in a Preface or Introduction to the book rather than […]

Chapter 10: Index of Refraction and Lens Conjugates

This Chapter is a little out of order but illuminates a topic we have hinted at in previous Chapters, how does the index of refraction affect the lens conjugates we see when doing centration? The immediate interest came from a call I got because some glass apparently got mixed up in a batch of identical […]

Chapter 9: Creating and Viewing Single Paraxial Ray

From the beginning we have said that centering a lens meant aligning the optical axis of the lens to a reference axis. Up to this point we have assumed the axis was the mechanical axis of a rotary table. Because there are disadvantages to using a rotary table, I was curious to see if there […]

Chapter 8: Alignment of 3 Centers of Curvature

A convenient and concrete example of aligning three centers of curvature is the cementing of the doublet we used in the optical axis example in Chapter 5, the details of which are reproduced below. Fig. 1 Doublet used as an example of aligning three centers of curvature The goal is to get all three centers […]

Chapter 7: Centering 2 Centers of Curvature

In the previous chapter we looked at finding a single center of curvature using any of several optical instruments. This locates a particular point in space but does not define an axis. For that, two centers of curvature separated by a finite axial distance must be located to define an axis, or line. This chapter […]

Chapter 6: Centering on a Single Center of Curvature

In this Chapter we will discuss the centering of a single center of curvature of a lens in a cell sitting on a rotary table that creates a reference axis. This discussion describes the traditional method of centering a lens in a cell. While this does not sound like an ambitious goal, the ideas presented […]

Chapter 5: Optical Axis Definition

The purpose of optical alignment is making the optical axis of an optical element, or complete system, coaxial with some other axis that is defined by other optical or mechanical components. This means we must start the discussion of optical alignment by making sure we all mean the same thing when we say the optical […]

Chapter 4: Autostigmatic Microscope

There is no better way to describe an autostigmatic microscope (ASM) than to call it an autocollimator (AC) with a microscope objective attached to the front. This converts the AC from an instrument that measures 2 angular degrees of freedom (DOF) into an instrument that measures the location of the center of curvature of a […]

Chapter 3: Classical Optical Alignment Instruments

Fig. 1 A simple collimator with a point source of illumination. An illuminated target in the same plane could serve as the source. Collimators are used as a light source for testing camera lenses on a nodal slide optical bench. The collimator simulates a point source, or in astronomical terms, a star, at infinity. For lens […]

Chapter 2: Three Methods of Alignment

In the Introduction to this series of articles on optical alignment, I said there were three basic methods of alignment. This article presents my thoughts on these methods. My approach may be a bit unconventional, but I hope this way of beginning makes the whole idea of alignment easier to understand. To illustrate the three […]

Chapter 1: Introduction

Introduction to a Series of Articles on Optical Alignment For some time, I have been encouraged to write a book about optical alignment. There have been several half-hearted attempts at beginning, but it never seemed there was enough to talk about and I kept finding new ideas about alignment. I didn’t want the book to […]

A Short History of the CaliBall™ and the Random Ball Test

Back in the late 1990’s NIST had a number of firms that wanted to send their interferometer transmission spheres there for calibration but NIST was not in this sort of calibration business. While I was at NIST consulting for Chris Evans in the Precision Machining Facility we thought of the idea of a self-calibration test […]

Practical Optical Tabletop Alignment

Many research projects begin as tabletop assemblies of optical components to move light from a source through an interaction zone to change the character of the light and on to a detector. The quality of the signal reaching the detector depends on the optical alignment of all the components between the source and detector. The […]

What is an Autostigmatic Microscope (ASM) and the Origin of the Point Source Microscope (PSM)

When most people think of a microscope it is one that works in transmission with the light source on one side of the sample and the microscope objective and eyepiece on the other. An autostigmatic microscope (ASM) works in reflection, just like an autocollimator, so the light source is in the microscope body, and is […]