Far field imaging with short - focal length lens : Fourier configuration


Far field imaging with short - focal length lens : Fourier...

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optoabhi
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Hello,

UPDATE TITLE: Fourier Plane image

  1. How could I design a system where a short-focal length lens (doublet, EFL = 7.5mm, BFL = 4.45mm and Dia = 6.25) is used to image the Fourier plane in the system.
  2. The object is 1cm tall and 15um wide rectangular illuminated aperture.
  3. I did the initial setup design and the attached is my ZMX file. However, this design setup is meant to image the object onto the image plane. The objective is to get the Fourier plane of the object. How do I obtain that, please advise.



Reference for the position of Fourier plane: From "Fundamentals of photonics" by Saleh-Teich Edition 2




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DEV-03.zmx (3 views, 15.00 KB)
David
David
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optoabhi - Thursday, July 13, 2017 10:00 AM
Hello,

How could I design a system where a short-focal length lens (doublet, EFL = 7.5mm, BFL = 4.45mm and Dia = 6.25) is used to obtain the far field image of an object.
The entire playable track length range is 40mm. Since that is such a short range, I am left with choosing a doublet with specs mentioned above. The object is 1cm tall and 15um wide rectangular illuminated aperture.

I did the initial setup design and the attached is my ZMX file. However, this design setup is meant to image the object onto the image plane. The objective is to get the Fourier of the object. How do I obtain that, please advise.

Click To Enlarge

Hello,
What is wanted is the condition in which the parallel rays are mapped unique points in the image plane. This is the case when the image plane is located at the back focal plane of the lens. So you want the image plane at the back focal plane, and the object, in this case your slit, is located close enough that all rays of interest make it through the lens. This is what this looks like for a paraxial model:


Notice that parallel rays map to the same image location independent of their object height.

To accomplish that with your design, I made a few modifications. I reversed the lens so that the fastest side faced the lower curvature side of the lens. I changed the entrance pupil to object cone angle and a telecentric object space. I moved the lens close to the object to accept a 30 degree cone half-angle. I then used a real ray height solve (REAY) in the merit function to set the back focal distance such that a real ray from a 70% field height, but parallel the optical axis had a height of zero on the image plane. (All rays parallel the optical axis should have zero height on the image plane.) This is done with an optimization that has nothing to do but that. Here is the result:



I have tried attached both files as ZARs, but I am getting a forum error that I have already exceeded a size limit. If the files do not post, I will add them to a next reply.

Kind regards,
David

PS: is UH Hawaii? Where there are BIG telescopes?





David
David
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David - Thursday, July 13, 2017 12:37 PM
optoabhi - Thursday, July 13, 2017 10:00 AM
Hello,

How could I design a system where a short-focal length lens (doublet, EFL = 7.5mm, BFL = 4.45mm and Dia = 6.25) is used to obtain the far field image of an object.
The entire playable track length range is 40mm. Since that is such a short range, I am left with choosing a doublet with specs mentioned above. The object is 1cm tall and 15um wide rectangular illuminated aperture.

I did the initial setup design and the attached is my ZMX file. However, this design setup is meant to image the object onto the image plane. The objective is to get the Fourier of the object. How do I obtain that, please advise.

Click To Enlarge

Hello,
What is wanted is the condition in which the parallel rays are mapped unique points in the image plane. This is the case when the image plane is located at the back focal plane of the lens. So you want the image plane at the back focal plane, and the object, in this case your slit, is located close enough that all rays of interest make it through the lens. This is what this looks like for a paraxial model:


Notice that parallel rays map to the same image location independent of their object height.

To accomplish that with your design, I made a few modifications. I reversed the lens so that the fastest side faced the lower curvature side of the lens. I changed the entrance pupil to object cone angle and a telecentric object space. I moved the lens close to the object to accept a 30 degree cone half-angle. I then used a real ray height solve (REAY) in the merit function to set the back focal distance such that a real ray from a 70% field height, but parallel the optical axis had a height of zero on the image plane. (All rays parallel the optical axis should have zero height on the image plane.) This is done with an optimization that has nothing to do but that. Here is the result:



I have tried attached both files as ZARs, but I am getting a forum error that I have already exceeded a size limit. If the files do not post, I will add them to a next reply.

Kind regards,
David

PS: is UH Hawaii? Where there are BIG telescopes?





I tried to attach the files again, but again failed. You can find my email in my forum contact information. If you send me email I will send you the zar files.



David
David
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David - Thursday, July 13, 2017 12:43 PM
David - Thursday, July 13, 2017 12:37 PM
optoabhi - Thursday, July 13, 2017 10:00 AM
Hello,

How could I design a system where a short-focal length lens (doublet, EFL = 7.5mm, BFL = 4.45mm and Dia = 6.25) is used to obtain the far field image of an object.
The entire playable track length range is 40mm. Since that is such a short range, I am left with choosing a doublet with specs mentioned above. The object is 1cm tall and 15um wide rectangular illuminated aperture.

I did the initial setup design and the attached is my ZMX file. However, this design setup is meant to image the object onto the image plane. The objective is to get the Fourier of the object. How do I obtain that, please advise.

Click To Enlarge

Hello,
What is wanted is the condition in which the parallel rays are mapped unique points in the image plane. This is the case when the image plane is located at the back focal plane of the lens. So you want the image plane at the back focal plane, and the object, in this case your slit, is located close enough that all rays of interest make it through the lens. This is what this looks like for a paraxial model:


Notice that parallel rays map to the same image location independent of their object height.

To accomplish that with your design, I made a few modifications. I reversed the lens so that the fastest side faced the lower curvature side of the lens. I changed the entrance pupil to object cone angle and a telecentric object space. I moved the lens close to the object to accept a 30 degree cone half-angle. I then used a real ray height solve (REAY) in the merit function to set the back focal distance such that a real ray from a 70% field height, but parallel the optical axis had a height of zero on the image plane. (All rays parallel the optical axis should have zero height on the image plane.) This is done with an optimization that has nothing to do but that. Here is the result:



I have tried attached both files as ZARs, but I am getting a forum error that I have already exceeded a size limit. If the files do not post, I will add them to a next reply.

Kind regards,
David

PS: is UH Hawaii? Where there are BIG telescopes?





I tried to attach the files again, but again failed. You can find my email in my forum contact information. If you send me email I will send you the zar files.




And what are all these weird characters?
optoabhi
optoabhi
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David - Thursday, July 13, 2017 12:43 PM
David - Thursday, July 13, 2017 12:37 PM
optoabhi - Thursday, July 13, 2017 10:00 AM
Hello,

How could I design a system where a short-focal length lens (doublet, EFL = 7.5mm, BFL = 4.45mm and Dia = 6.25) is used to obtain the far field image of an object.
The entire playable track length range is 40mm. Since that is such a short range, I am left with choosing a doublet with specs mentioned above. The object is 1cm tall and 15um wide rectangular illuminated aperture.

I did the initial setup design and the attached is my ZMX file. However, this design setup is meant to image the object onto the image plane. The objective is to get the Fourier of the object. How do I obtain that, please advise.

Click To Enlarge

Hello,
What is wanted is the condition in which the parallel rays are mapped unique points in the image plane. This is the case when the image plane is located at the back focal plane of the lens. So you want the image plane at the back focal plane, and the object, in this case your slit, is located close enough that all rays of interest make it through the lens. This is what this looks like for a paraxial model:


Notice that parallel rays map to the same image location independent of their object height.

To accomplish that with your design, I made a few modifications. I reversed the lens so that the fastest side faced the lower curvature side of the lens. I changed the entrance pupil to object cone angle and a telecentric object space. I moved the lens close to the object to accept a 30 degree cone half-angle. I then used a real ray height solve (REAY) in the merit function to set the back focal distance such that a real ray from a 70% field height, but parallel the optical axis had a height of zero on the image plane. (All rays parallel the optical axis should have zero height on the image plane.) This is done with an optimization that has nothing to do but that. Here is the result:



I have tried attached both files as ZARs, but I am getting a forum error that I have already exceeded a size limit. If the files do not post, I will add them to a next reply.

Kind regards,
David

PS: is UH Hawaii? Where there are BIG telescopes?





I tried to attach the files again, but again failed. You can find my email in my forum contact information. If you send me email I will send you the zar files.




I just did email you, thank you.


Research Assistant
UH
optoabhi
optoabhi
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Forum Newbie (341 reputation)Forum Newbie (341 reputation)Forum Newbie (341 reputation)Forum Newbie (341 reputation)Forum Newbie (341 reputation)Forum Newbie (341 reputation)Forum Newbie (341 reputation)Forum Newbie (341 reputation)Forum Newbie (341 reputation)

Group: Forum Members
Posts: 21, Visits: 248
David - Thursday, July 13, 2017 12:37 PM
optoabhi - Thursday, July 13, 2017 10:00 AM
Hello,

How could I design a system where a short-focal length lens (doublet, EFL = 7.5mm, BFL = 4.45mm and Dia = 6.25) is used to obtain the far field image of an object.
The entire playable track length range is 40mm. Since that is such a short range, I am left with choosing a doublet with specs mentioned above. The object is 1cm tall and 15um wide rectangular illuminated aperture.

I did the initial setup design and the attached is my ZMX file. However, this design setup is meant to image the object onto the image plane. The objective is to get the Fourier of the object. How do I obtain that, please advise.

Click To Enlarge

Hello,
What is wanted is the condition in which the parallel rays are mapped unique points in the image plane. This is the case when the image plane is located at the back focal plane of the lens. So you want the image plane at the back focal plane, and the object, in this case your slit, is located close enough that all rays of interest make it through the lens. This is what this looks like for a paraxial model:


Notice that parallel rays map to the same image location independent of their object height.

To accomplish that with your design, I made a few modifications. I reversed the lens so that the fastest side faced the lower curvature side of the lens. I changed the entrance pupil to object cone angle and a telecentric object space. I moved the lens close to the object to accept a 30 degree cone half-angle. I then used a real ray height solve (REAY) in the merit function to set the back focal distance such that a real ray from a 70% field height, but parallel the optical axis had a height of zero on the image plane. (All rays parallel the optical axis should have zero height on the image plane.) This is done with an optimization that has nothing to do but that. Here is the result:



I have tried attached both files as ZARs, but I am getting a forum error that I have already exceeded a size limit. If the files do not post, I will add them to a next reply.

Kind regards,
David

PS: is UH Hawaii? Where there are BIG telescopes?




UH - University of Houston (Texas). That is an outdated signature, I am no longer studying at Texas. I dint know there are big telescopes at Hawaii, now I wish to visit there.



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UH
David
David
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optoabhi - Thursday, July 13, 2017 12:55 PM
David - Thursday, July 13, 2017 12:37 PM
optoabhi - Thursday, July 13, 2017 10:00 AM
Hello,

How could I design a system where a short-focal length lens (doublet, EFL = 7.5mm, BFL = 4.45mm and Dia = 6.25) is used to obtain the far field image of an object.
The entire playable track length range is 40mm. Since that is such a short range, I am left with choosing a doublet with specs mentioned above. The object is 1cm tall and 15um wide rectangular illuminated aperture.

I did the initial setup design and the attached is my ZMX file. However, this design setup is meant to image the object onto the image plane. The objective is to get the Fourier of the object. How do I obtain that, please advise.

Click To Enlarge Click To Enlarge

Hello,
What is wanted is the condition in which the parallel rays are mapped unique points in the image plane. This is the case when the image plane is located at the back focal plane of the lens. So you want the image plane at the back focal plane, and the object, in this case your slit, is located close enough that all rays of interest make it through the lens. This is what this looks like for a paraxial model:
Click To Enlarge

Notice that parallel rays map to the same image location independent of their object height.

To accomplish that with your design, I made a few modifications. I reversed the lens so that the fastest side faced the lower curvature side of the lens. I changed the entrance pupil to object cone angle and a telecentric object space. I moved the lens close to the object to accept a 30 degree cone half-angle. I then used a real ray height solve (REAY) in the merit function to set the back focal distance such that a real ray from a 70% field height, but parallel the optical axis had a height of zero on the image plane. (All rays parallel the optical axis should have zero height on the image plane.) This is done with an optimization that has nothing to do but that. Here is the result:

Click To Enlarge

I have tried attached both files as ZARs, but I am getting a forum error that I have already exceeded a size limit. If the files do not post, I will add them to a next reply.

Kind regards,
David

PS: is UH Hawaii? Where there are BIG telescopes?




UH - University of Houston (Texas). That is an outdated signature, I am no longer studying at Texas. I dint know there are big telescopes at Hawaii, now I wish to visit there.



I noticed your update with the Fourier filter diagram. This design imposes an additional requirement in that a second transform is made so as to provide 1:1 reimaging of the input, with a Fourier plane in the middle. In this case, the spacing should be as shown in the diagram. This can be determined mechanically either by using the published front and back focal distances (not the focal length) or by using appropriate merit function ray operands (REAY, RAID) or solves to determine spacings. I have reported the forum issues to support, and I will respond to this by email to get around them.

Best,
David
David
David
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David - Friday, July 14, 2017 9:26 AM
optoabhi - Thursday, July 13, 2017 12:55 PM
David - Thursday, July 13, 2017 12:37 PM
optoabhi - Thursday, July 13, 2017 10:00 AM
Hello,

How could I design a system where a short-focal length lens (doublet, EFL = 7.5mm, BFL = 4.45mm and Dia = 6.25) is used to obtain the far field image of an object.
The entire playable track length range is 40mm. Since that is such a short range, I am left with choosing a doublet with specs mentioned above. The object is 1cm tall and 15um wide rectangular illuminated aperture.

I did the initial setup design and the attached is my ZMX file. However, this design setup is meant to image the object onto the image plane. The objective is to get the Fourier of the object. How do I obtain that, please advise.

Click To Enlarge Click To Enlarge

Hello,
What is wanted is the condition in which the parallel rays are mapped unique points in the image plane. This is the case when the image plane is located at the back focal plane of the lens. So you want the image plane at the back focal plane, and the object, in this case your slit, is located close enough that all rays of interest make it through the lens. This is what this looks like for a paraxial model:
Click To Enlarge

Notice that parallel rays map to the same image location independent of their object height.

To accomplish that with your design, I made a few modifications. I reversed the lens so that the fastest side faced the lower curvature side of the lens. I changed the entrance pupil to object cone angle and a telecentric object space. I moved the lens close to the object to accept a 30 degree cone half-angle. I then used a real ray height solve (REAY) in the merit function to set the back focal distance such that a real ray from a 70% field height, but parallel the optical axis had a height of zero on the image plane. (All rays parallel the optical axis should have zero height on the image plane.) This is done with an optimization that has nothing to do but that. Here is the result:

Click To Enlarge

I have tried attached both files as ZARs, but I am getting a forum error that I have already exceeded a size limit. If the files do not post, I will add them to a next reply.

Kind regards,
David

PS: is UH Hawaii? Where there are BIG telescopes?




UH - University of Houston (Texas). That is an outdated signature, I am no longer studying at Texas. I dint know there are big telescopes at Hawaii, now I wish to visit there.



I noticed your update with the Fourier filter diagram. This design imposes an additional requirement in that a second transform is made so as to provide 1:1 reimaging of the input, with a Fourier plane in the middle. In this case, the spacing should be as shown in the diagram. This can be determined mechanically either by using the published front and back focal distances (not the focal length) or by using appropriate merit function ray operands (REAY, RAID) or solves to determine spacings. I have reported the forum issues to support, and I will respond to this by email to get around them.

Best,
David

In the attached file (or by email if I can't attach it) the Fourier filter diagram is implemented. The Fourier plane is the stop. Symmetry is enforced with pickups. The Fourier plane is enforced in the merit function by an REAY operand which forces the distance to the stop so as to make a near-paraxial chief ray have zero height at the stop. (This could have used a chief-ray-height solve, except for the fact that the stop follows this surface.) The front focal distance is set by optimization for image quality, with the back focal distance the same by pickup.



GO


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