steve_bank
Diabetic retinopathy and poor eyesight. Typos ...
A post on Detecting ET brought back some memories.
Take a simple lens and point it at a distant circular object, lke the Sun. As you shrink the object diameter while mainlining intensity as the object diameter goes to zero the image in the focal plane goes to the 'sombrero function', Airy Disk. It isn3 dimensional.
Mathematically it is the convolution of an impulse function with a circular aperture. Thump a bell with your finger and you have convolved an time domain impulse with the bell, and it rimgs at its natural frequency.
In optics same math but spatial frequencies instead of mechanical or electrical frequencies.
In an audio system we have the electric bandwidth in electrical frequency. In optics the resolultion is spatial frequency, in line pairs per millmeter.
A small disk is an impulse to an optical system.
Trace a large number of rays parallel to the optical axis and plot in focl plane. This is the line spread function. tke the Fourier Trasfer of the line spread function and you get the spatial frequency response of the system. Analogous to electoral frequency respnse of an electrical system, same math.
Take an object of rectangular slots and shine a bright light behind it. At low spatial frequncy the patern a
square wave', is well defied in the focal plane. As the spatial frequency is increased the space between slots becomes blred.
Electrical systems are tested with square waves, the optical square wave is rectangular slots.
The modulation transfer function. Put a square wave into a low pass electrical filter. As frequency is increased you get a sine wave, harmonics are suppressed. In an optical system as spatial frequencies are increased you get a sine wave on the focal plane.
The blur spot
en.wikipedia.org
en.wikipedia.org
Things ted to reduce to some form of Fourier abalysys.
I guess my long term memory is still working.
A free version simulator
3doptix.com
If you are untested in learning some optics Warren Smith's book is an oldie but a goody. An easy read not a lot of math required.
Amazon product ASIN 0071476873
Take a simple lens and point it at a distant circular object, lke the Sun. As you shrink the object diameter while mainlining intensity as the object diameter goes to zero the image in the focal plane goes to the 'sombrero function', Airy Disk. It isn3 dimensional.
Mathematically it is the convolution of an impulse function with a circular aperture. Thump a bell with your finger and you have convolved an time domain impulse with the bell, and it rimgs at its natural frequency.
In optics same math but spatial frequencies instead of mechanical or electrical frequencies.
In an audio system we have the electric bandwidth in electrical frequency. In optics the resolultion is spatial frequency, in line pairs per millmeter.
A small disk is an impulse to an optical system.
Trace a large number of rays parallel to the optical axis and plot in focl plane. This is the line spread function. tke the Fourier Trasfer of the line spread function and you get the spatial frequency response of the system. Analogous to electoral frequency respnse of an electrical system, same math.
Take an object of rectangular slots and shine a bright light behind it. At low spatial frequncy the patern a
square wave', is well defied in the focal plane. As the spatial frequency is increased the space between slots becomes blred.
Electrical systems are tested with square waves, the optical square wave is rectangular slots.
The modulation transfer function. Put a square wave into a low pass electrical filter. As frequency is increased you get a sine wave, harmonics are suppressed. In an optical system as spatial frequencies are increased you get a sine wave on the focal plane.
The blur spot
Circle of confusion - Wikipedia
Optical transfer function - Wikipedia
Things ted to reduce to some form of Fourier abalysys.
I guess my long term memory is still working.
A free version simulator
Ray Optics Simulation - 3DOptix
Ray Optics Simulation Enhance productivity with 3DOptix, Optical design and Simulation software Ray Optics describes light propagation in terms of “rays” and is commonly concerned
3doptix.com
If you are untested in learning some optics Warren Smith's book is an oldie but a goody. An easy read not a lot of math required.
Amazon product ASIN 0071476873
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