In conclusion, the collaborative approach of the interprofessional team focused on patient education, personalized lens and eyewear selection, surgical options, and follow-up care aims to improve visual quality and enhance patient satisfaction when dealing with chromatic aberration.

The selection of lens materials for eyeglasses is a delicate balancing act. On one side is the refractive index, which can influence the thickness and aesthetic qualities of the lens. On the other is the Abbe number, which impacts chromatic aberration and visual comfort. These properties are also relevant for contact lens construction.[24] The best choice of material depends on the wearer's needs, including their prescription, visual requirements, aesthetic preferences, and sensitivity to chromatic aberration.

What is spherical aberrationin Physics

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Spherical aberration is a form of optical aberration that occurs when light rays passing through a lens at different distances from the optical axis are not brought into focus at the same point. This is because a simple lens has a spherical surface, and light rays that pass through the edges of the lens are refracted more than rays passing through the center.[27] The result is a blurry image with reduced sharpness and contrast. In severe cases, spherical aberration can cause halo-like rings around bright objects.[28] This phenomenon can be particularly noticeable in optical systems such as telescopes, microscopes, and even the human eye when considering high-prescription glasses or certain types of intraocular lenses.[29][30]

What is a spherical aberrationclass 12

An achromatic lens or achromat is the most common device to reduce chromatic aberration. An achromatic lens is a compound lens made of two or more elements, usually of crown and flint glass, designed to limit the effects of chromatic and spherical aberration.[6] The individual elements are chosen to have differing levels of dispersion. This ensures that light of different wavelengths focuses as closely as possible on a single point, thereby minimizing chromatic aberration across a specific range of wavelengths.[13] This point is known as the circle of least confusion.[14]

As for astigmatism, contact lenses can correct regular astigmatism as effectively as glasses. Yet, rigid contact lenses have an advantage over glasses in correcting irregular astigmatism. This is because rigid contact lenses create a regular refracting surface that masks the cornea's irregular shape, allowing for a more precise correction.[31]

Notably, the impact of chromatic aberration on refractive surgery is a reminder of the complex interplay between optical physics and human vision. By considering and accounting for such phenomena, surgeons can achieve the best possible results for their patients.

Understanding and mitigating chromatic aberration is crucial in photography, microscopy, medical optics, optometry, and ophthalmology, as it can significantly affect the quality of images and vision. Various strategies exist to reduce chromatic aberration, including using specialized lens materials and designs and digital post-processing techniques.

What is a spherical aberrationin photography

Contrast levels from 100% to 2% are illustrated on the right for a variable frequency sine pattern. Contrast is moderately attenuated for MTF = 50% and severely attenuated for MTF = 10%. The 2% pattern is visible only because viewing conditions are favorable: it is surrounded by neutral gray, it is noiseless (grainless), and the display contrast for CRTs and most LCD displays is relatively high. It could easily become invisible under less favorable conditions.

In early applications of lenses, chromatic aberration was often mitigated by increasing the lens's focal length where possible. For instance, this led to the construction of very long aerial telescopes in the 17th century.[8][9] Modern telescopes and other catoptric and catadioptric systems continue to utilize mirrors, which exhibit no chromatic aberration.[10]

Chromatic aberration can be classified into two types: axial (longitudinal) chromatic aberration (ACA) and transverse (lateral) chromatic aberration (TCA).[1] These are often confusingly abbreviated as LCA for both terms. Hence, the utilizations of ACA and TCA will be used in this passage.

Toric IOLs correct astigmatism and are designed to decrease spherical and cylindrical aberrations. Despite their efficacy in these areas, like all IOLs, toric IOLs are still subject to chromatic aberration.[46]

Multifocal IOLs provide clear vision at multiple distances (near, intermediate, and far). Their complex design incorporates diffractive and refractive elements and can induce a higher degree of chromatic aberration than monofocal IOLs.[43] As a result, patients with multifocal IOLs may experience more visual disturbances like glare and halos around lights, particularly in dim lighting.

In both these research fields, the minimization of chromatic aberration is critical to achieving clear and precise observations. This highlights the broader significance of chromatic aberration beyond its impacts on human vision, extending into scientific research and discovery.

In conclusion, various devices and strategies are available to combat chromatic aberration, each with strengths and weaknesses. The choice of method depends on the application's specific requirements, whether in telescopes, microscopes, cameras, or the human eye.

This relationship among refractive index, lens thickness, Abbe number, and chromatic aberration is a critical aspect of lens design, underlining the intricate nature of crafting eyeglass lenses and the importance of considering multiple factors to ensure optimal visual correction and comfort. Other parameters, such as the density of the lens material, may also play a role in the choice of spectacle lens material.[20]

Chromatic aberration, while primarily discussed in human vision and optics, has significant implications in various research fields. Electron microscopy and astronomy are two areas where the understanding and mitigation of chromatic aberration play an essential role in acquiring high-quality visual information.

What is a spherical aberrationexample

An alternative to achromatic doublets is the use of diffractive optical elements. These elements are essentially flat but can generate arbitrary complex wavefronts. They have negative dispersion characteristics, complementing the positive Abbe numbers of optical glasses and plastics. In the visible spectrum, diffractives have a negative Abbe number of -3.5.[18][19]

Additional explanations of human visual acuity can be found on pages from the Nondestructive testing resource center and Stanford University. Page 3 from Stanford has a plot of the MTF of the human eye. I believe the x-axis units (CPD) are Cycles per Degree, where a pair of 1/60 degree features corresponds to 30 CPD.

The image above represents only 0.5 mm of film, but takes up around 5 inches (13 cm) on my monitor. At this magnification (260x), a full frame 35mm image (24x36mm) would be 240 inches (6.2 meters) high and 360 inches (9.2 meters) wide. A bit excessive, but if you stand back from the screen you'll get an feeling for the effects of the lens, film, scanner (or digital camera), and sharpening on real images.

EDOF IOLs, similar to multifocal lenses, offer a continuous range of vision from near to far, reducing reliance on reading glasses. Their design, which uses diffractive and refractive principles, can cause a slightly higher chromatic aberration level than monofocal IOLs.[44][45]

Chromatic aberration is a fundamental concept in optics, impacting the design and functionality of optical devices, lens construction, and the execution of refractive surgeries. Its manifestation as color fringing in visual perception challenges attaining optimal visual quality. Techniques to mitigate its effects, from material choice to sophisticated lens design, are integral to advancements in optical technology and ophthalmic care. In an era where visual acuity is paramount, understanding and effectively managing chromatic aberration remains at the forefront of delivering superior visual outcomes and enabling control of the visual pathway in multiple disciplines, such as optical devices and photography. Hence, chromatic aberration is not just an academic concept but a critical practical concern influencing vision in multifaceted ways.

Chromatic aberration has significant implications in refractive surgery, which aims to improve visual acuity and reduce dependence on glasses or contact lenses. This optical phenomenon can impact the surgical process and the quality of the patient's postoperative vision, making it a critical consideration in these procedures.

Regarding chromatic aberration, contact lenses and glasses can produce this phenomenon as they bend different light wavelengths by varying amounts. However, chromatic aberration is generally less noticeable with contact lenses because they stay centered over the pupil, moving with gaze. This helps to minimize the chromatic aberration seen when vision is directed away from the optical center of the lens, as the gaze is always run through the optical center of a well-centered contact lens.[28]

Moreover, post-surgical visual quality can be affected by chromatic aberration. As the surgery alters the path of light through the eye, it can exacerbate the dispersion of light and increase the perception of chromatic aberration. Patients may notice this as color fringes around bright objects or a reduced visual contrast, particularly in low-light conditions.[35]

The Abbe number is defined as Vd = (nd - 1) / (nf - nc), where nd, nf, and nc represent the refractive indices of the material for the Fraunhofer d-, f-, and c-lines, respectively. These lines correspond to specific wavelengths of light, specifically the yellow (d-line, 589 nm), blue (F-line, 486 nm), and red (C-line, 656 nm) regions of the spectrum.[20]

How is MTF related to lines per millimeter resolution? The old resolution measurement— distinguishable lp/mm— corresponds roughly to spatial frequencies where MTF is between 5% and 2% (0.05 to 0.02). This number varies with the observer, most of whom stretch it as far as they can. An MTF of 9% is implied in the definition of the Rayleigh diffraction limit.

The lens's material and design heavily influence the chromatic aberration magnitude in an IOL. The lens's dispersion properties, characterized by the Abbe number, mainly determine chromatic aberration levels.[39] Hence, IOLs with a higher Abbe number have lower dispersion and less chromatic aberration.[40]

Patient education is a crucial component of the management strategy. Nurses and vision therapists can provide vital instruction about chromatic aberration and its potential impacts. Patients experiencing high levels of chromatic aberration may benefit from advice on managing their visual disturbances, including tips on reading under appropriate lighting conditions or avoiding certain low-light situations.

Chromatic aberration happens when different light colors get refracted or bent differently as they pass through the IOL, leading to "color fringing" or colored halos around objects. This effect can decrease visual acuity and contrast sensitivity, interfering with everyday tasks such as reading or driving, particularly in low-light conditions.[38]

The sharpness of a photographic imaging system or of a component of the system (lens, film, image sensor, scanner, enlarging lens, etc.) is characterized by a parameter called Modulation Transfer Function (MTF), also known as spatial frequency response. We present a unique visual explanation of MTF and how it relates to image quality. A sample is shown on the right. The top is a target composed of bands of increasing spatial frequency, representing 2 to 200 line pairs per mm (lp/mm) on the image plane. Below you can see the cumulative effects of the lens, film, lens+film, scanner and sharpening algorithm, based on accurate computer models derived from published data. If this interests you, read on. It gets a little technical, but I try hard to keep it readable.

However, this advantage comes with a trade-off. High-index lens materials typically have a lower Abbe number, indicating greater dispersion, the refractive index variation with wavelength. As discussed in the earlier section on the Abbe number, greater dispersion can lead to more chromatic aberration, causing colored fringes around objects and blurring of the image. While low-index lenses may be thicker and potentially less aesthetically pleasing, they tend to have higher Abbe numbers, thus resulting in less chromatic aberration. This can improve visual comfort for the wearer, especially in situations with bright light or high contrast, which can exacerbate chromatic aberration.[20]

Various IOL designs use different strategies to minimize chromatic aberration. Some IOLs utilize low-dispersion materials or incorporate aspheric designs to counteract chromatic and optical aberrations. Recent advancements have led to the development of "achromatic" or "apochromatic" IOLs, which correct chromatic aberration across various wavelengths. Although it is impossible to eliminate chromatic aberration, these improvements significantly reduce its impact, enhancing vision quality post-cataract surgery.[41]

Different types of IOLs, including monofocal, multifocal, extended depth of focus (EDOF), and toric lenses, introduce unique considerations concerning chromatic aberration.[41]

Most of us are familiar with the frequency of sound, which is perceived as pitch and measured in cycles per second, now called Hertz. Audio components— amplifiers, loudspeakers, etc.— are characterized by frequency response curves. MTF is also a frequency response, except that it involves spatial frequency— cycles (line pairs) per distance (millimeters or inches) instead of time. The mathematics is the same. The plots on these pages have spatial frequencies that increase continuously from left to right. High spatial frequencies correspond to fine image detail. The response of photographic components (film, lenses, scanners, etc.) tends to roll off at high spatial frequencies. These components can be thought of as lowpass filters— filters that pass low frequencies and attenuate high frequencies.

In electron microscopy, chromatic aberration can be a significant limitation to the images' resolution. Electron microscopes utilize electromagnetic lenses subject to chromatic aberration like light-based systems. The spread of electron velocities (or energies) in the microscope's beam results in a variation in focal lengths, causing chromatic blur. To mitigate this, scientists often employ strategies like chromatic aberration correction, which uses multiple elements to correct for the aberrations introduced by the objective lens.[49] This enables them to capture detailed, high-resolution images of the microscopic world.

Another approach to mitigate chromatic aberration involves using special glasses with low optical dispersion, such as glasses containing fluorite. These hybridized glasses exhibit a very low level of optical dispersion. Two combined lenses made of these substances can yield a high correction level.[17]

In conclusion, it is accurate to suggest that contact lenses can reduce some optical aberrations compared to glasses. In the context of chromatic aberration specifically, opting for a lower dispersion spectacle lens material may be a more effective direct reduction method, making the suggestion of contact lenses potentially less effective but not incorrect.[21] These differences can influence the choice between glasses and contact lenses, which ultimately depends on the patient's circumstances and their provider's professional judgment.

The optical qualities and correct placement of intraocular lenses (IOLs) are critical components in cataract surgery, where they replace the eye's natural lens that has become clouded due to cataracts. Like any other optical system, IOLs can be subject to chromatic aberration, which affects the quality of vision post-surgery.

For instance, materials with a higher Abbe number in ophthalmic lenses may be used to reduce chromatic aberration, particularly for individuals with high refractive errors. In such cases, the benefits of reduced color distortion often outweigh the drawbacks of potentially thicker lenses, as further described below. When choosing a spectacle lens material, the Abbe number is taken into account along with other parameters, such as the index of refraction, the density, and the transmission, to determine the lowest weight and thinnest lens while retaining the best optical qualities.[18]

At a distance d from the eye (which has a nominal focal length of 16.5 mm), this corresponds to objects of length = (angle in radians)*d = 0.000291*d. For example, for an object viewed at a distance of 25 cm (about 10 inches), the distance you might use for close scrutiny of an 8x10 inch photographic print, this would correspond to 0.0727 mm = 0.0029 inches. Since a line pair corresponds to two lines of this size, the corresponding spatial frequency is 6.88 lp/mm or 175 lp/inch. Assume now that the image was printed from a 35mm frame enlarged 8x. The corresponding spatial frequency on the film would be 55 lp/mm.

Monofocal IOLs, designed to offer clear vision at a single distance (usually far), provide a good balance between low dispersion and high optical quality across a broad light spectrum but are subject to chromatic aberration.[42]

Fortunately, modern IOL designs, incorporating lower dispersion materials (higher Abbe number) and aspheric or apochromatic designs, can help minimize chromatic aberration. However, balancing visual performance, refractive correction, and minimizing chromatic and other optical aberrations is a significant consideration in IOL design and selection.[40] Ongoing research continues to develop and refine IOL technologies to improve visual outcomes and patient satisfaction.[47][48][47]

Film imaging systems consist of a lens, film, developer, scanner, image editor, and printer (for digital prints) or lens, film, developer, enlarging lens, and paper (for traditional darkroom prints). Digital camera-based imaging systems consist of a lens, digital image sensor, de-mosaicing program, image editor, and printer. Each of these components has a characteristic frequency response; MTF is merely its name in photography. The beauty of working in frequency domain is that the response of the entire system (or group of components) can be calculated by multiplying the responses of each component.

The figure below represents a sine pattern (pure frequencies) with spatial frequencies from 2 to 200 cycles (line pairs) per mm on a 0.5 mm strip of film. The top half of the sine pattern has uniform contrast. The bottom half illustrates the effects of Provia 100F on the MTF. Pattern contrast drops to half at 42 cycles/mm.

What is spherical aberrationand How can it be corrected

The statement that the eye cannot distinguish features smaller than one minute of an arc is, of course, oversimplified. The eye has an MTF response, just like any other optical component. It is illustrated on the right from the Handout #9: Human Visual Perception from Stanford University course EE368B - Image and Video Compression by Professor Bernd Girod. The horizontal axis is angular frequency in cycles per degree (CPD). MTF is shown for pupil sizes from 2 mm (bright lighting; f/8), to 5.8 mm (dim lighting; f/2.8). At 30 CPD, corresponding to a one minute of an arc feature size, MTF drops from 0.4 for the 2 mm pupil to 0.16 for the 5.8 mm pupil. (Now you know your eye's f-stop range. It's similar to compact digital cameras.) Another Stanford page has Matlab computer models of the eye's MTF.

Similarly, chromatic aberration significantly affects astronomy, particularly in observational astrophysics using telescopes. As in microscopes, telescopes use lenses and mirrors to gather and focus light. Here, chromatic aberration can blur the images of celestial objects as different light colors (wavelengths) are refracted by different amounts.[50] Historically, this was one reason for developing very long focal-length lenses in early telescopes. Modern astronomy mitigates chromatic aberration with the use of mirror-based (catoptric) systems, such as reflector telescopes, which don't suffer from chromatic aberration, and advanced lens systems like apochromats, which significantly correct chromatic aberration.[51]

The reduction of spherical aberration in contact lenses is due to their positioning directly on the cornea, maintaining a consistent distance across the entire lens.[28] This contrasts with glasses that sit farther from the eye, with a distance that varies across the lens, especially in high-prescription glasses, potentially increasing spherical aberration.

Effective management of chromatic aberration and its impact on visual quality necessitates a comprehensive, multi-disciplinary approach. This team comprises ophthalmologists, optometrists, nurses, ophthalmic technicians, opticians, and vision therapists, all of whom must understand chromatic aberration and its effects on a patient's vision and everyday life.

The design of the lens system also significantly impacts the degree of chromatic aberration. For instance, using an achromatic doublet, which combines a positive lens made from a high-dispersion glass and a negative lens made from a low-dispersion glass, can minimize chromatic aberration.[6] Similarly, combining the cornea and the lens somewhat reduces chromatic aberration.[7]

What is a spherical aberrationused for

This is especially important when choosing a lens material for someone requiring safety glasses. The two main choices of high-impact resistant plastic are polycarbonate and urethane pre-polymer (Trivex). Polycarbonate and Trivex have indices of refraction of 1.586 and 1.531 and Abbe values of 30 and 43, respectively. Therefore, the index of refraction difference is small, but the large difference in Abbe value may determine whether to choose Trivex over polycarbonate when correcting higher refractive errors.[25][26][25]

The red curve is the spatial response of the bar pattern to the film + lens. The blue curve is the combined MTF, i.e., the spatial frequency response of the film + lens, expressed in percentage of low frequency response, indicated on the scale on the left. (It goes over 100% (102).) The thin blue dashed curve is the MTF of the lens only.

Spherical aberrationand chromaticaberration

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Standard Depth of Field (DOF) scales on lenses are based on the assumption, made in the 1930s, that the smallest feature of importance, viewed at 25 cm, is 0.01 inches— 3 times larger. It shouldn't be a surprise that focus isn't terribly sharp at the DOF limits. See the DOF page for more details.

One vital intervention area is patient counseling on lens selection and eyewear design. Opticians, optometrists, and ophthalmologists are critical in guiding patients toward the most suitable lens materials, designs, and eyewear based on their needs. Factors such as the patient's refractive error, lifestyle, and tolerance to chromatic aberration determine the choice between low-index and high-index lenses and eyewear designs that minimize chromatic aberration. High-index lenses, while thinner and lighter, exhibit more chromatic aberration than low-index lenses, a trade-off that patients must understand when selecting. Moreover, by working closely with opticians and optical technicians, healthcare professionals can help patients choose eyewear designs with special materials or coatings, like anti-reflective coating, that can mitigate the effects of chromatic aberration.

Axial chromatic aberration (ACA) occurs when different wavelengths of light are focused at different distances along the optical axis.[2] This effect can occur throughout the image and is often specified by optical professionals in diopters.[3] ACA can be reduced by decreasing the aperture of a lens (reducing the f-stop in a photography scenario), which increases the depth of field so that although different wavelengths focus at varying distances, they create a smaller blur circle.[4] In digital sensors, axial CA results in the red and blue planes being defocused, which is relatively difficult to remedy in post-processing.[5]

The edges in the bar pattern have been broadened, and there are small peaks on either side of the edges. The shape of the edge is inversely related to the MTF response: the more extended the MTF response, the sharper (or narrower) the edge. The mid-frequency boost of the MTF response is related to the small peaks on either side of the edges.

To mitigate chromatic aberration in refractive surgery, several strategies have been developed. For instance, specific surgical lasers are equipped with sophisticated optical systems that correct for chromatic aberration in the surgical view.[36] Furthermore, advanced surgical planning techniques can account for potential chromatic aberration in the design of the surgical correction, helping to ensure a clear postoperative visual outcome.[37]

Chromatic aberration, also referred to as chromatic distortion, color fringing, and spherochromatism, is a common optical phenomenon that occurs when a lens cannot bring all wavelengths of light to a single converging point. Chromatic aberration manifests as the lens's inability to focus all colors on the same axis, causing noticeable distortions or color mismatches in high-contrast scenarios. This property of light is of significant interest in optometry, ophthalmology, and medical optics, with applications and considerations ranging from lens design to diagnostic procedures.

Chromatic aberration, a distortion in the focusing of light due to different colors bending at different angles as they pass through a lens, can degrade image quality in various applications, from photography to microscopy.[11][12] Thus, numerous strategies have been devised to counteract this optical phenomenon. These strategies leverage different lens materials, designs, and devices.

Contact lenses, due to their unique interaction with the eye and the alteration of the light path, can help reduce some aberrations compared to glasses, particularly under high refractive error conditions.

This means that for an 8x10 inch print, the MTF of a 35mm camera (lens + film, etc.) above 55 lp/mm, or the MTF of a digital camera above 2800 LW/PH (Line Widths per Picture Height) measured by Imatest SFR, has no effect on the appearance of the print. That's why the highest spatial frequencies used in manufacturer's MTF charts is typically 40 lp/mm, which provides an excellent indication of a lens's perceived sharpness in an 8x10 inch print enlarged 8x. Of course higher spatial frequencies are of interest for larger prints.

Transverse chromatic aberration (TCA) occurs when different wavelengths of light are focused at different positions perpendicular to the optical axis. This results in color fringes along the boundaries separating the image's dark and bright parts. TCA does not occur in the center of the image and increases towards the edge. It is not affected by reducing the f-stop. In digital sensors, TCA results in the red, green, and blue planes having different magnifications and can be corrected by radially scaling the planes so they line up.[5]

Counseling on surgical options is integral when considering refractive surgery or intraocular lens (IOL) implantation. Healthcare providers are responsible for informing patients about the potential for chromatic aberration with different types of IOLs, including monofocal, multifocal, EDOF, and toric lenses. Clear and precise communication about these possibilities helps manage patient expectations and improves satisfaction after surgery.

What is a spherical aberrationin optics

However, even achromatic lenses do not provide perfect correction; they generally focus only two wavelengths—red and blue—sharply. The degree of correction can be enhanced by combining more than two lenses of different compositions, as in an apochromatic lens or apochromat. These lenses aim to bring three wavelengths—red, green, and blue—into focus in the same plane. The terms "achromat" and "apochromat" refer to the type of correction (2 or 3 wavelengths correctly focused, respectively), not the degree of correction. Thus, an apochromat made with low-dispersion glass can yield better correction than an achromat made with conventional glass.[15] The true benefit of apochromats is that they focus three wavelengths sharply, and their error in focusing other wavelengths is relatively small.[16]

The Abbe number, also known as V-number or constringence, measures a material's dispersion in relation to the refractive index. Dispersion is the variation of a lens's refractive index based on light's wavelength. A higher distribution means that different wavelengths of light will deviate more significantly when passing through the material, causing the various colors to separate and potentially resulting in chromatic aberration.[20]

Precision is paramount during refractive surgery, with procedures such as LASIK and PRK involving the precise reshaping of the cornea to correct refractive errors like myopia, hyperopia, and astigmatism.[32][33] Chromatic aberration can impact the surgeon's view and the accuracy of these procedures. The different wavelengths of light refracted by the ocular tissues can result in a blurred surgical field or inaccurate measurements, potentially compromising surgical outcomes.[34]

The refractive index of a lens material measures how much the material can bend or refract light. It's an important parameter in optical science and lens design, influencing the efficiency of a lens in bending light to correct vision. Materials with a higher refractive index bend light more strongly than those with a lower refractive index.[23] This bending capability is particularly beneficial when crafting lenses for eyeglasses, as it allows for thinner lenses. For example, in cases of high prescription values for severe conditions such as severe myopia (nearsightedness), using a high-index material can result in a thinner, lighter, and more aesthetically pleasing lens than a lens made of a lower-index material offering the same corrective power.

The essential meaning of MTF is rather simple. Suppose you have a pattern consisting of a pure tone (a sine wave). At frequencies where the MTF of an imaging system or a component (film, lens, etc.) is 100%, the pattern is unattenuated— it retains full contrast. At the frequency where MTF is 50%, the contrast half its original value, and so on. MTF is usually normalized to 100% at very low frequencies. But it can go above 100% with interesting results.

Lastly, regular follow-up care is essential to ensuring that the chosen intervention, be it a specific lens, eyewear, or surgery, meets the patient's visual needs and expectations. Patients should be encouraged to report any visual disturbances indicating a potential market for further adjustments.

In practical applications, lens manufacturers must balance the need for a high refractive index (to achieve thinner lenses) against the desire for a high Abbe number (to minimize chromatic aberration). Typically, materials with a high refractive index have a lower Abbe number and vice versa. Selecting lens materials often requires a compromise between these two properties.[22]

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Materials with a higher Abbe number have lower dispersion, leading to less chromatic aberration. In contrast, materials with a lower Abbe number exhibit higher dispersion and a greater likelihood of chromatic aberration.[21]