What Abbe number of lens? | ABBE Glasses - abbe number

 2024-08-23 07:56:56

How does this relate to the limited diffraction? Imagine a perfect lens with no aberrations, not limited by design or manufacturing flaw. Each point light source will create an airy disk, and when an image is properly resolved the airy disks do not overlap. When the outer rings merge, the sensor will be diffraction limited. The only way to improve resolution will be to increase the numerical aperture. But when the center of each airy disk merges, we’ve reached the limit of resolution; the diffraction cutoff frequency. When you’ve reached the limit of resolution you’ll not be able to resolve further even by increasing aperture.

Optical lenses

With the addition of the new 60X objective, which employs newly developed glass for enhanced chromatic aberration correction, quantitative imaging in thick living specimens has never been more attainable.

This article— part two of our series on “Avoid Optical Pitfalls”— will look at what the diffraction limited is, how to calculate it, and how it can affect the resolution of high performance optics.

Small intestine enteroid (Cadherin: Alexa Fluor® 555, Nuclear: DAPI)Images courtesy of: Dr. Yuki Yokoi, Dr. Kiminori Nakamura, and Dr. Tokiyoshi AyabeInnate Immunity Laboratory, Department of Cell Biological Science, Faculty of Advanced Life ScienceGraduate School of Life Science, Hokkaido University Science, Hokkaido University

It is also best suited for long time-lapse imaging of live cells without the immersion medium evaporating because silicone oil has low volatility even at 37°C.

Germanium IRLens

The diffraction limit is essentially the resolution limit that is imposed on an optical system by the wave nature of light and the process of diffraction. To understand this, let’s look at what diffraction does when light shines through an opening.

The silicone immersion lens series features wide fields of view, high resolution, and evaporation-resistant oil, facilitating observations with ease.

There’s a mistake people often make when assessing the performance of a microscope or telescope— forgetting the diffraction limit. It is a theoretical limiting factor governing the maximum obtainable resolution of an optical system. When we leave it out of our calculations we may end up with very unrealistic expectations.

Aspheric lenses

By refracting short-wavelength light to a higher degree, it is possible to collect a wider range of wavelengths, resulting in significantly enhanced chromatic aberration correction. In addition to axial chromatic aberrations, lateral chromatic aberrations can also be corrected.

For visible light microscopy, the diffraction limit— the smallest detail that can be resolved— is about 200-250 nanometers.

Infraredlens

Fertilized mouse embryoImage courtesy of: Dr. Yoshiteru Kai, Reproductive Medicine Research Center, YAMASHITA SHONAN YUME CLINIC

What is the cutoff frequency of the lens, the diffraction limit? We can calculate it using the same two parameters we used to calculate the radius of our airy disks. The equation is:

No; the passage of light through the atmosphere introduces significant distortions that limit performance to a lower resolution than provided by diffraction limited observation.

Any lens has a finite aperture, and when light passes through an aperture— no matter its size— diffraction will occur. We call a diffraction pattern an Airy disk, and it is disk shaped. There is a bright area in the center surrounded by concentric rings, and each ring decreases in brightness as you move out. This Airy disk is the key to the diffraction limit, as it is the Airy disk which is the smallest point to which you can focus a beam of light. We sometimes call this the ‘minimum spot size’ of an optical system.

Silicone contactlens

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Research applications in neuroscience and cell biology using brain tissue, spheroids, organoids, and 3D cultures continue to push the limits of imaging in thick specimens. The need to image deep into such samples has never been more apparent. Nikon’s silicone immersion objectives enable clear observation with high signal-to-noise deep into living tissue.

Neutrophil flowing in blood vessel (time-lapse)Images courtesy of: Professor Masaru Ishii, Department of Immunology and Cell Biology, Graduate School of Medicine, Osaka University

Plano-convexlens

The diffraction limit tells us that there is a limit to the resolution of images we can obtain, no matter how much we improve our optical system. Although this limit is not important for everyday photography or situations in which resolution is already limited by other significant optical aberrations, it is important to microscopy, telescopic, and high resolution photography.

Time-lapse imaging of enteroid (25X)Images courtesy of: Dr. Yuki Yokoi, Dr. Kiminori Nakamura, and Dr. Tokiyoshi AyabeInnate Immunity Laboratory, Department of Cell Biological Science, Faculty of Advanced Life ScienceGraduate School of Life Science, Hokkaido University

Small intestine organoidImage courtesy of: Dr. Hidenori Akutsu and Dr. Tomoyuki Kawasaki of the Center for Regenerative Medicine, National Center for Child Health and Development

The radius of the Airy disk depends on two important factors: the wavelength of light and the size of the aperture, and we can estimate it with the equation: Ra = 1.22λ/2Na. In this equation Ra is the airy radius, λ is the wavelength of illuminating light, and Na the numerical aperture.

The new silicone immersion 60X objective employs high- and specialized-dispersion glass that was independently developed by Nikon and possesses extra-low dispersion properties.

As the numerical aperture increases, the radius of the airy disk decreases. In modern optics, the numerical aperture can be as high as 1.4-1.6. The table below shows the diameter of an airy disk for lenses of different apertures when the lens is illuminated with light at 520 nm.

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