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# Laser Diode Beam Basics Manipulations And Characterizations Pdf

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Published: 16.05.2021  Haiyin Sun received a Ph. He has over twenty years industrial and academic experience in laser diode applications and characterizations, lens designs, mathematical modeling, project management etc.

## Laser Diode Beam Propagation Basics

Thin lens equation modified to be applicable for laser beams is introduced. An example about collimating and focusing a laser diode beam is presented. Raytracing technique is briefly discussed. Keywords Thin lens equation Propagation Collimating Focusing Beam spot Gaussian beam Geometric rays To understand laser diode beam propagation characteristics, some basic knowledge about laser beam propagation theory is necessary.

Such beams are basic TE mode Gaussian beams. The characteristics of a Gaussian beam are described by a set of three equations . Figure 2. From Eq.

As the beam propagates, R z gradually decreases. As the beam continues propagating, the beam wavefront gradually becomes spherical, then R z becomes proportional to z.

The ratio between these two radii is about 1. Similarly, the percentage laser energy encircled inside the half magnitude radius can be calculated by. Many literatures studying this subject have been published. The most cited one is the book written by Siegman .

It is difficult to find the mode structure details in these beams, since the unavoidable measurement errors often lead to inconclusive results. But all these non-basic Gaussian mode beams will have far field divergences larger than the far field divergences of basic mode Gaussian beams with the same beam waist radii. A practical way of handling such laser beams is to neglect the mode structure details, assume the beams still have Gaussian intensity distributions and introduce a M 2 factor to the beams.

Figures 2. Most collimated single TE mode laser diode beams have a M 2 of 1. M 2 factor has been widely used now to describe various quasi Gaussian laser beams. Some laser developers even use M 2 factor to describe multi TE mode laser beams. To this author s opinion, this is not an appropriate use of M 2 factor. With some modifications, thin lens equation can be used to describe how a laser beam propagates through a lens.

In this book we use thin lens equation as the main mathematical model. For o?? It s noted that the actual smallest possible focused spot radius is the diffraction limited radius 1. Equation 2. Section 2. The waist of a collimated laser diode beam is a few millimeters, the z R of the collimated beam is several meters. The maximum and minimum focusing distances i max and i min are marked by the black dots and squares on each curve.

We can see from Fig. The solid curves are for geometric rays emitted by an object point for comparison. The black dots denote the focal points of the lens. In this section we draw several graphs to provide a more clear view about the collimating or focusing of a laser diode beam. We start from the collimating situation. We note that the waist size of the beam output from the lens changes in Fig.

When the waist of the input laser beam moves from the collimated position shown in Fig. According to Eqs and 2. In Fig. It s noted that the drawings in Fig. The focusing characteristics of a laser diode beam is illustrated in Fig We start from the situation shown in Fig. We note that in Fig. The drawings in Fig. The solid curves and dash curves are for the beams in the fast and slow axis directions, respectively mm i m.

In both a and b the solid and dash curves are for the fast and slow axis directions, respectively From Eq. The i versus o curve, and the w F and w S versus o curves described by Eqs and 2. It s noted that the middle points at the horizontal and vertical axes in Fig. It can be seen that in the fast axis direction, the maximum focusing distance is about 43 m, in the slow axis direction the maximum focusing distance is about 4. In a collimation situation shown in Fig.

After being collimated, the laser diode beam has larger waist radius and smaller divergence in the fast axis direction than in the slow axis. The i versus o curve, and the w F and w S versus o curves are plotted in Fig. As we can see in Fig. The maximum and minimum focusing distances in the fast axis direction is about 1.

From Fig. We call this phenomenon ghost astigmatism. For the setup shown in Fig. The best focused beam has the largest focused spot, that sounds weird, but it is the characteristics of Gaussian laser beams. So, if we want a smallest possible focused spot, we can defocus the beam. In some applications, more accurate step by step raytracing is required. A conceived incident ray perpendicularly passing through the wavefront at this contacting point can be determined, as shown in Fig Applying Snell law to this ray, we can determine a conceived ray refracted by the lens surface.

References 1. Siegman, A. Siegman, AE. SPIE , 2 14 3. Self, S. Sun, H. Equipment Reflection and Refraction Acrylic block set, plane-concave-convex universal mirror, cork board, cork board stand, pins, flashlight, protractor, ruler, mirror worksheet, rectangular block worksheet,.

Objective Geometric Optics Converging Lenses and Mirrors Physics Lab IV In this set of lab exercises, the basic properties geometric optics concerning converging lenses and mirrors will be explored. The diameter of the moon is 3. Journal of the Korean Physical Society, Vol. AP Physics B Ch. Choose the one alternative that best completes the statement or answers the question.

McCarron December 7, 1 Introduction Acousto-optic modulators AOMs are useful devices which allow the frequency, intensity and direction of a laser beam. Crystal Optics of Visible Light This can be a very helpful aspect of minerals in understanding the petrographic history of a rock.

The manner by which light is transferred through a mineral is a means. Theory Refer to your Lab Manual, pages For a plane mirror, compared to the object distance, the image distance is always A less B greater C the same 2. Which graph best represents the relationship between image distance di and object. One report per group is due by. Text reference: pp Optics Bench a For convenience of discussion we assume that the light. Experiment 3 Lenses and Images Who shall teach thee, unless it be thine own eyes?

Euripides ? We assume that we can ignore the wave properties of light. Lenses and Mirrors 1. You stand two feet away from a plane mirror. How far is it from you to your image? Which of the following best describes the image from. Understanding Laser Beam Parameters Leads to Better System Performance and Can Save Money Lasers became the first choice of energy source for a steadily increasing number of applications in science, medicine.

Convex Mirrors Center of curvature and focal point both located behind mirror The image for a convex mirror is always virtual and upright compared to the object A convex mirror will reflect a set of parallel. Chapter Mirrors and Lenses How do you see sunspots?

When you look in a mirror, where is the face you see? What is a burning glass? Make sure you know how to:. Apply the properties of similar triangles;.

Physics Spring 1 Purpose Fraunhofer Diffraction The experiment will test the theory of Fraunhofer diffraction at a single slit by comparing a careful measurement of the angular dependence of intensity. Holographically corrected microscope with a large working distance as appears in Applied Optics, Vol.

Knize Laser and Optics Research Center. Work through all. Alignement of a ring cavity laser 1 Introduction This manual describes a procedure to align the cavity of our Ti:Sapphire ring laser and its injection with an Argon-Ion pump laser beam. ## Laser Diode Beam Basics, Manipulations and Characterizations

Thin lens equation modified to be applicable for laser beams is introduced. An example about collimating and focusing a laser diode beam is presented. Raytracing technique is briefly discussed. Keywords Thin lens equation Propagation Collimating Focusing Beam spot Gaussian beam Geometric rays To understand laser diode beam propagation characteristics, some basic knowledge about laser beam propagation theory is necessary. Such beams are basic TE mode Gaussian beams.

Search this site. A Lone Gunman? Ace It! Geografie: Graad 11 PDF. Acqua Alta PDF. Front Matter. Pages i-ix. PDF · Laser Diode Basics. Haiyin Sun. Pages · Laser Diode Beam Propagation Basics. Haiyin Sun. Pages · Single Transverse.

## A Practical Guide to Handling Laser Diode Beams

It seems that you're in Germany. We have a dedicated site for Germany. Many optical design technical books are available for many years which mainly deal with image optics design based on geometric optics and using sequential raytracing technique. Some books slightly touched laser beam manipulation optics design. On the other hand many books on laser diodes have been published that extensively deal with laser diode physics with little touching on laser diode beam manipulations and characterizations.

Thin lens equation for a real laser beam with weak lens aperture truncation H Sun Optical Engineering 37 11 , , A practical guide to handling laser diode beams H Sun Springer , Measurement of laser diode astigmatism H Sun Optical Engineering 36 4 , ,

He holds various management, engineering and research positions in L-3 Communications, Coherent Inc. He was an editorial board member of Journal of Optical Communications Germany , an adjunct assistant professor of applied science at The University of Arkansas, and served in several program committees in SPIE conferences. Sun is the primary author of about thirty peer review journal papers, one book and one book chapter on optical and laser technologies. This book offers the reader a practical guide to the control and characterization of laser diode beams. Correct handling of laser diode beams is the key to the successful use of laser diodes, and this requires an in-depth understanding of their unique properties. Following a short introduction to the working principles of laser diodes, the book describes the basics of laser diode beams and beam propagation, including Zemax modeling of a Gaussian beam propagating through a lens.  