PhET Hands-On Practice

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From the course by University of Colorado Boulder

First Order Optical System Design

29 ratings

University of Colorado Boulder

First Order Optical System Design

29 ratings

Course 1 of 3 in the Specialization Optical Engineering

Optical instruments are how we see the world, from corrective eyewear to medical endoscopes to cell phone cameras to orbiting telescopes. When you finish this course, you will be able to design, to first order, such optical systems with simple mathematical and graphical techniques. This first order design will allow you to develop the foundation needed to begin all optical design as well as the intuition needed to quickly address the feasibility of complicated designs during brainstorming meetings. You will learn how to enter these designs into an industry-standard design tool, OpticStudio by Zemax, to analyze and improve performance with powerful automatic optimization methods.

From the lesson

Introduction to Geometrical Optics

This module introduces rays, which we use to describe the motion of light through air and materials. The course overview describes the goals of this course and gives tips on how to make the best use of the course materials to be successful. The lectures introduce the material. The in-video questions, lab demonstrations, PhET interactive demonstration, practice problems, and homework assignment allow you to get actively involved in learning the material.

Snells Laws6:50

Fermat's Principle4:18

Snell's Laws in the Laboratory5:28

PhET Hands-On Practice5:13

Meet the Instructors

Amy Sullivan
Research Associate
Electrical, Computer and Energy Engineering
Robert McLeod
Professor
Electrical, Computer and Energy Engineering

This video is designed to give you some hands on practice in your own

virtual laboratory.

The first thing that we're going to do is go to the PhET website for

interactive simulations.

Once we go to the website, you want to click on Play with Simulations.

We choose Physics over on the left.

We go down and we want to pick Light and Radiation, and then choose Bending Light.

And we can go ahead and play this or you can download it.

There's a number of different options here, and

I encourage you to play with them all.

We'll start out with Introduction.

The first thing I want to look at is waves.

So up here in the left-hand corner, you can pick Wave.

And this is my light source.

So the first thing I want to do is turn it on,

and I see that I have light leaving the light source.

I'm going to give it a little bigger angle so things look bigger.

And I can see the wave fronts leaving the light source, and

heating the surface of this material.

So the material on the top is listed as air, and

the material on the bottom is listed as water, and we change that to glass.

Really looks I bend more,

the index reflection glass is higher than that of the water.

You can stop this, you can do this in slow motion if you want.

You can see here that the wave fronts are all aligned on the surface.

You can also see that this is a little bit cumbersome, even in a demonstration,

so we might want to switch to raise.

And so I can look at raise.

And so some things that I would encourage you to do with now, is play around.

This is a single surface, you can change the angle of the instant light,

and you can use a protractor to measure the angles.

The angle incidence, the angle of reflection, the angle of refraction.

If you want, we haven't talked about this yet but

you can also measure some intensities.

And figure out how much light is going into the material, and

how much light is being reflected.

You can change the materials.

And one thing that you might want to do is there's a choice here to air,

water, glass, we can custom change your own index reflection.

There's a mystery material, Mystery A, mystery B.

So you can change this around, and see if you can change this around and

calculate what the index refraction of the mystery materials are.

This is good practice.

Next thing that I want to check is,

if you look down at the bottom, there is a link that says Prisms.

And this is different types of glass.

So again, I get a light source which I can go ahead and turn that on.

I can make it have lots of different rays.

I can make it a white light source.

I can change its wavelength.

We can put different things in here.

I can put a prism in here.

I can get total internal reflection if I want.

I can figure out where that angle is, For different prisms.

And I can do a big block of material.

I can even do some lenses, and see how that changes light as well.

There's a lot of things to play around with here.

And it's good if you don't have the lab in your own home to play around with this,

and see you have a lot of flexibility in changing the types of material.

We can even take a circle here and we can fill it with water.

One of my favorite things to do is then to take this water, and

make this a white light source.

And it turns out if we add in reflections,

one more thing you can add in, it makes it a little more complicated.

But you can see that the light enters this circle of water,

and it bounces off and it comes out, and it actually forms a rainbow.

I think that's really neat, so this is how rainbows are formed in the sky.

The light from the sun,

and it bounces around in the rain drop, and it forms rainbows.

So you can do lots of different things here to play around, and

see what happens, just the basic principles.

What happens when we have different rays of light?

Can turn off reflections if there are too many beams here.

See what happens with different things.

So play around, get some intuition.

See if you can measure things.

Find out if you can make things bend in a way that you expect, and

try to predict what you think might happen.

And there's some more tools here as well.

And actually we'll check

the speed of light in and out.

And you can play around with all the different tools here.

So that's so fun, play around and

try how many different things you can make up in with just a couple arrays of light.

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