NTNUJAVA Virtual Physics Laboratory
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JDK1.0.2 simulations (1996-2001) => Optics => Topic started by: Fu-Kwun Hwang on January 29, 2004, 10:57:18 pm



Title: Thin Lens combinations
Post by: Fu-Kwun Hwang on January 29, 2004, 10:57:18 pm
This java applets let you understand the entire range of behavior of a single convex lens or image formed by two lens.



How to use it:
You will see single convex lens and a block with four different at each corner.
You will also find images for those corner.
It is like viewing the image of a 3 dimensional object.
The image is distorted and its length is reduced more than its height.
The magnification transverse to the axis is greater than the longitudinal magnification along the axial direction.
Click within the area of the block will show light path for different points.
The location for the object p and object q are shown near the top,

the focus length are labeled at the bottom.
You can click within the small circle at the focus point and drag the mouse to change the focus point.
Click at the top left corner of the block and drag the mouse to move it.
Click the bottom right corner of the block and drag it to change its size.
The mouse position is displayed as ( x, y ) value.

Click the right mouse button to have another lens,  Click it again to remove it.
 x2 is the location of the mouse tip relative to the second lens.  d is the distance between two lens.
You will find image formed by two lens.
Click within lens area and drag the mouse to move the lens.
 Click the circle between lens to change the focus length.
You can simulate image formed by lens combination experiments with this java applets.
All the related parameters are shown, record it and perform a virtual experiment.


Emulate refracting telescope:Enlarge the image of a distant object.The object is at a finite far distance from the device, so that the intermediate image is located beyond the image focus of the objective. The inverted intermediate image served as the object for the eyepiece, which function as a magnifier. Magnifying power = f1 / f2
Emulate compound microscope:The lens system closest to the object is the objective. It forms a real, inverted, magnified image of the object that is then viewed by the eyepiece. The latter is essentially a magnifying glass that looks at and enlarge the image created by the objective. The total angular magnification od the system  = d * 25.4(cm)/ (f1 *f2)


Title: topic47
Post by: on May 27, 2004, 05:53:59 pm
Could there be some display problem with this applet ?

I had f = 50, [b:c5e8d6fe77]p[/b:c5e8d6fe77] = 70 and the applet read [b:c5e8d6fe77]q[/b:c5e8d6fe77]= 96 but as I move my mouse over the image the x,y coordinates read 175 which is what [b:c5e8d6fe77]q[/b:c5e8d6fe77] should be


Title: topic47
Post by: mustafadmrc on June 17, 2005, 05:57:19 am
I made a calculation and found  :arrow: if f=50 and p=70 q must be 175 :!:  but in applet it's 96 :?:   :?:


Title: Sorry for the bug, it is fixed
Post by: Fu-Kwun Hwang on June 17, 2005, 10:32:54 am
I am sorry that the applet show the correct image position, however, the value was incorrect.
It is fixed now.

Thank you!


Title: topic47
Post by: mustafadmrc on July 15, 2005, 05:30:48 am
Thank you mr Hwang. I think you do your job very well and i have to thank you for permission of using your applets offline. I searched a lot but i found a few sites who gives permission to use their applets offline. I think knowledge increases if its shared.
                                                                                                     Best regards


Title: 2 Concave lens combination - help me!!
Post by: bhavin365 on November 29, 2005, 07:04:44 pm
The applet of COMBINATION OF 2 CONVEX LENS is really superb. But if both the lens are CONCAVE and/or combination of Convex and Concave then what? Depending on your above mentioned applet, my students are now asking for the dynamic applet look of combination of 2 concave lens.

Please help me out!!

best regards,
bhavin


Title: 2 Concave lens combination
Post by: ott on March 18, 2006, 07:16:24 pm
The applet is very nice. Thank you. It shows the construction rays of imaging (i.e. one ray through the focal point, one ray through the prinicpal point). However in optical engineering the stop position (and the resulting pupils) is essential for imaging. Once it its defined the chief ray and the marginal ray can be drawn. These rays are much more important than the construction rays because they define for example the perspective and the resolution that can be obtained. For expample most microscopes are telecentric, i.e. the stop is located at the focal point (image side), therefore the chief ray on the object side is parallel to the optical axis. This avoids a 'breathing' of the image when focusing.

Best regards

Peter Ott


Title: Re: Thin Lens combinations
Post by: rmokhtar on March 15, 2009, 08:01:30 pm
I have a question about the following two sentences:

"The image is distorted and its length is reduced more than its height.
The magnification transverse to the axis is greater than the longitudinal magnification along the axial direction."

because I am translating this and have absolutely no idea what they are referring to. When I tried to test this, I took the lengths and heights in the image and original and compared them. In the instance I was measuring, the ratio of the lengths (parallel to the optical axis) was 4 times larger in the image than the original, whereas the heights were 1.25 and 2.9 times larger in the image than the original.

So, again, I am confused, or maybe I am misunderstanding the sentences: How is it that the length is enlarged less (or reduced more, that also confused me) than its height when distorted?


Title: Re: Thin Lens combinations
Post by: Fu-Kwun Hwang on March 15, 2009, 08:17:07 pm
If the ratio of width and height between image and object are the same, then the image is not distored.
However, in real case, the ratio of width and height  between image and object are not the same.

widthimage/widthobject ≠ heightimage /heightobject

That is the reason I said the image is a distoration of the object.
Because the relation betweeb object and image are calculated from:
 1/p +1/q =1/f
 and
heightimage /heightobject= q/p

for object with width w, at position p
1/(p-w/2)+1/q1=1/f
1/(p+w/2)+1/q2=1/f
The width of the image is |q2-q1| !
The height of the image are between q2/(p+w/2) and q1/([-w/2)

Forexample:
The object is the small rectangle at the left side of the following image.
However, the image is not a square any more. And
 (http://www.phy.ntnu.edu.tw/java/thinLens/telescope.gif)







Title: Re: Thin Lens combinations
Post by: dscott6001 on April 10, 2009, 03:29:17 am
I have studied the examples and am quite interested in the longitudinal versus transverse dimensions of the image.
For clarification:  The square object lies in the longitudinal plane, as does the trapezoidal image? The more distant vertical dimension of the object is magnified in the image more than the nearest vertical dimensions of the object ?  The java applet does not deal with directions transverse to the optical axis shown?

Thanks for your clarification

DMS




Title: Re: Thin Lens combinations
Post by: Fu-Kwun Hwang on April 10, 2009, 07:55:01 am
As shown in the attached image,even I only calcuate those 4 points image of a square and connect those 4 points image in the simulation. The real image is still in trapezoidal shape.
But the center point  in the object is not corresponds to center point in the image (check out the second image-a snap shot image from the following URL).

Please check out object in front of concave/convex lens (http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=377.0) for more detail calculated image. You can dra any point in the object and find out the corresponding image points.


Title: Re: Thin Lens combinations
Post by: buymmlensf on October 02, 2010, 01:17:15 am
Thanks


Title: Re: Thin Lens combinations
Post by: koclup1580 on November 15, 2012, 12:31:26 pm
thank you......... :o