When armed robbers enter your home, you will have friends coming to the movies.
Of course, you can easily beat them with your ninja skills and guidance --
But in the process your TV is damaged and now your movie night is destroyed!
Don't be afraid, now you have a few simple parts that you can save a day.
I have had a similar situation and there are only some differences --
My friend is moving out, so there is no TV, but we are destined to watch horror movies as usual.
So with all the knowledge of high school physics, I came up with this simple design.
Basically, we will use a magnifying glass to focus the light on the laptop's screen into an image.
This is designed for personal use or educational purposes to illustrate thin-
Use lens optics in a convenient, fun and cheap way.
The brightness of the projection depends largely on the brightness of the projected image and the optical system used.
I will solve these two problems in time.
Okay, now to the yellow copper nail (
Note: actual brass nails may or may not be required).
Take stock: 1.
The brighter the laptop or computer monitor, the better. 2. Storage tub 3.
Magnifying Glass 4.
Tape measure 5. Scissors 6.
Paper and pencil. Calculator 8.
Cardboard is everything you need to make a projector.
For calibration, however, I recommend using some additional material: 9.
A directional light source, like a lamp 10. String 11.
Something translucent with text or pictures on it, such as a newspaper cut or a receipt.
You 've heard it many times before: "Can it wait a while?
I'm doing some calibration.
"Well, now you have to do some calibration!
That is to say, we need to get some data to determine the focal length of our lens.
I don't know what the focal length is?
It doesn't matter, we will discuss it in the calculation in the next section.
In general, this is the number associated with the distance the lens will focus the image.
To achieve this number, we need to set up a small projector: 1.
Objects that will be projected onto the light source are as flat as possible, but leave enough space for the heat to escape, otherwise your hands will catch fire (
Or on your desk). 2.
Hang the magnifying glass at about 1 feet in front of the light source to put it in the beam path. Mine was at 20. 3cm (8in. ).
Measure the distance from the angle of the lens to the object.
This is done, the distance to the object. 3.
Stick a piece of paper to a book or other object as a screen.
Make sure it is high enough to be in the beam path. 4.
Place the screen at a certain distance from the lens. Mine was at 90. 17cm (35. 5in). 5.
Turn off the light and turn on the light source. 6.
Move the screen back and forth until the projected image is focused.
Measure the distance from the center of the lens to the screen.
This will be the di of the distance image. 7.
Select a function on the screen that can be measured.
Record this number as image size S2.
Measure this same feature on the original object and record it as object size S1. 8.
Turn off the lights and remove the installer.
After the calibration is complete, you can go and save the galaxy.
Since all your attention belongs to us, we can learn some math secretly.
The values we have just collected from the calculations will be used for the thin lens equation, a simplified version of the lens manufacturer equation.
Technically, our lens is not particularly thin, but the approximation is very good, avoiding a lot of math and measurement.
Based on the data we collect, we will calculate the focal length of the lens, which is based on the inherent properties of the lens with the radius of curvature, and tell us the extent to which the lens bends the light.
We will calculate the focal length by two methods and use the mean value of the values we get (
To minimize errors).
Method 1: the thin lens equation is fairly simple and involves di, do, and f.
F = 16 according to my calculation. 57cm.
Method 2: The magnification of the zoom lens is usually an important feature, simply the ratio of the image size to the size of the object.
Here, there is a negative sign for this ratio due to the image upside down.
Magnification can also be related to f and do.
The focal length obtained by this calculation is f = 16. 64.
These calculations are very consistent, only 0.
There is a 4% difference between them.
Now that we have the focal length, we can determine the di and do the next calculation for our actual projector.
Here I set di to 177. 8cm (5. 83ft).
Why do you use such a good even number?
Well, this just makes the calculation so simple!
I just calculated this number based on how far my desk is from the wall.
You can choose any number you want, but there are a few things to note: 1)
The smaller your di, the smaller your image will be, but the brighter it will be
You have to do this, the lens is usually 150-180cm (5-6ft)
This is a good distance for di as the image will be large but still visible.
Once you know your do and di, you are ready for the next step!
I also included a ray map showing how the convex lens bends the light from the object to form a real image.
This happens only when the object is outside the lens focal length.
Otherwise, a virtual image will be generated (
This is how a magnifying glass is usually used).
Okay, no math!
Now, we need to grab the cardboard and cut a piece of cardboard corresponding to the internal dimensions of the storage box so that it can be installed comfortably.
Depending on your image source, you may need to subtract the thickness of your laptop from one dimension (
See the first picture).
Now find the center of the rectangle.
The easiest way is to draw the diagonal lines of the rectangle and find the intersection of them.
Then drop your lens, track it, and cut out a hole a little smaller than it, so the lens fits comfortably.
According to your calculation, mark the appropriate position in the storage box of the cardboard (do)
Put it there.
Place the projector at an appropriate distance from the screen/wall (di)
, Remember to measure from the center of the lens! .
You're almost ready to be the most awesome person at the party!
A few things: 1)
We use a single lens, so the image is reversed.
So you need to rotate the image on the screen.
This can be done from any graphics card you use in the graphics control panel.
I use Nvidia so I turn on the Nvidia control panel and rotate the display. 2)
The lens won't capture all the light on the screen, so you want it to be as bright as possible.
You can turn up the brightness all the way, but it may not be enough.
I went back to the Nvidia control panel to maximize the brightness, increase the gamma value, and increase the digital vibration (
Compensate for the Effect of gamma on color). 3)
The calculation is based on a thin lens approximation, so you may need to adjust the distance a little.
Only slightly changing the distance between the lens and the laptop will greatly change the focus distance, so use this for overall adjustment (
If the image is very blurry).
Fine tuning will be achieved by moving the entire projector.
However, this approximation is very accurate, so you should not make too many adjustments to the system. 4)
Turn off the lights and crack!
If your laptop is quiet, consider connecting the speaker to the headphone port.
You will also use a lot of power, so be sure to plug your computer in.
I hope you like my first note.
I have been reading all of your tutorials for years, but now I have something of my own to contribute.