For more than a century, Corning's products played a role in developing vaccines and medicines and helping to get them safely to the public from the tubes, ...

Curvature of field in optical microscopy is an aberration that is familiar to most experienced microscopists. This artifact is the natural result of using lenses that have curved surfaces.

[1] Each pixel on a colour image sensor has either a red, green, or blue colour filter, which is different than the way colour is handled by the pixels on a typical monitor.  Each individual pixel on a monitor has a combination of red, green, and blue subpixels.

Explore the relationship between astigmatism and comatic aberrations, and how astigmatism aberrations are manifested by the off-axis image of a specimen point appearing as a line or ellipse instead of a point.

collimation - Translation and Meaning in Almaany English-English Dictionary. collimation. [n] the accurate adjustment of the line of sight of a telescope ...

Optical aberration

Both CCD and CMOS sensors come in colour and monochromatic (also called “black and white” though the sensors actually produce images in greyscale) varieties.

Departures in lens action from the ideal conditions of optics are known as aberrations. Optical trains typically suffer from as many as five common aberrations: spherical, chromatic, curvature of field, comatic, and astigmatic.

An ideal microscope objective produces a symmetrical diffraction limited image of an Airy pattern from an infinitely small object point. The image plane is generally located at a fixed distance from the objective front lens in a medium of defined refractive index. Microscope objectives offered by the leading manufacturers have remarkably low degrees of aberrations and other imperfections, provided the appropriate objective is selected for the task and the objective is utilized properly in accordance with the manufacturer's recommendations. It should be emphasized that objective lenses are not made to be perfect from every standpoint, but are designed to meet certain specifications depending on their intended use, constraints on physical dimensions, and price ranges.

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In CMOS sensors, each individual pixel contains a photodetector (usually a photodiode – i.e., a diode that generates current when light is incident upon it) with a circuit containing a number of transistors. The circuit controls the pixel’s functions such as activating or resetting the pixel, or reading its signal out to an analog-to-digital converter.

Brian O. Flynn, John C. Long, Matthew Parry-Hill, and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.

Chromatic aberration

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Therefore, as the magnification of the microscope is increased, the field of view will decrease proportionally and vice versa as an increase in magnification by ...

Stellar aberration

Apr 8, 2023 — Notice, though, that it's 24x24 and not 44x44. My guess is that since a minimum target size will be required in version 2.2, the guidelines are ...

Each of the individual pixels on a colour sensor does not receive the full RGB information. This fact, along with the demosaicing process, results in an image whose effective resolution is slightly less than that of a monochromatic camera with the same size and pixel count [4]. Monochromatic cameras also have higher a greater response to a given incident irradiance than colour cameras, as none of the light incident on the pixels is filtered out.

Thermal cameras measure infrared (IR) light and use it to infer temperature. A number of technologies exist for making such cameras. One example is a microbolometer array, which consists of an array of specialized pixels. The top layer of these pixels is a material that changes resistance when heated by IR light. The change in resistance is then measured by underlying electronics to infer temperature. The array of pixels then generates a thermal image, showing the spatially-resolved temperature of the imaged object.

Jul 3, 2023 — A scanning objective lens will provide 4x magnification, a low power magnification lens will provide magnification of 10x, and a high power ...

It must be noted that the quality of CMOS sensors has developed rapidly over the last few years and the advantages in performance that CCDs have had historically are diminishing. Some CCDs still have advantages in dynamic range, uniformity, and IR performance and are preferred for some scientific and industrial applications [2]. Nonetheless, CMOS-based detectors are available that are suitable for most applications, in addition to those for which they have been historically preferred. Ultimately the required specifications and cost of the sensor are what must be considered.

Forceps are a handheld, hinged instrument used for grasping and holding objects. Forceps are used when fingers are too large to grasp small objects or when ...

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Curvature of field in optical microscopy and how it is a common and annoying aberration that is familiar to most experienced microscopists is explained in this featured interactive tutorial.

Discover an aberration-free meridional section of a point source of light located at a depth in the specimen layer having a refractive index and imaged with a virtual microscope objective.

The glass and the liquid have the same refractive index, which means that they both bend light the same amount. A refractive index of 1 means ...

Ryan Field is an Optical Engineer at StarFish Medical. Ryan holds a PhD in Physics from the University of Toronto. As a post doctoral fellow, he worked on the development of high-power picosecond infrared laser systems for surgical applications as well as a spectrometer from home materials.

Historically speaking, CCD-based sensors have had a lower noise level, a higher single-shot dynamic range, a more uniform response to light across the entire sensor, and greater sensitivity in low light due to a higher pixel fill factor.  On the other hand, CMOS sensors have been capable of much higher frame-capture rates, lower power consumption, higher responsivity, and were less expensive at volume [1]. This led to CMOS sensors being preferred in low-cost/low-power applications such as smartphone and other consumer cameras, and in cases where high frame-capture rates are needed. CCD cameras have had performance advantages in cases where high sensitivity, low noise, and/or high uniformity are needed, such as certain low-light applications.

For microscope objectives having apertures, the optical properties and thickness of the medium lying between the front lens element and the specimen affect the calculations necessary to correct for image aberrations.

Spherical aberration

Explore the two most prevalent types of distortion, positive and negative, and how they can often be present in very sharp images that are otherwise corrected for spherical, chromatic, comatic, and astigmatic aberrations.

Because the pair of orthogonal waves is superimposed, it can be considered a single wave having mutually perpendicular electrical vector components separated by ...

Coma aberration

This blog is the third in a series discussing things to consider when choosing a sensor for a medical device camera. The first entry in this blog series covered camera sensor resolution and pixel size. The second entry covered considerations related to incident irradiance, exposure time, gain, and frame rate, and their impact on figures of merit such as dynamic range and signal-to-noise ratio.

Objectives are made with differing degrees of optical correction for both monochromatic (spherical, astigmatism, coma, distortion) and polychromatic aberrations, field size and flatness, transmission wavelengths, freedom from fluorescence, birefringence and other factors contributing to background noise. Depending upon the degree of correction, objectives are generally classified as achromats, fluorites, and apochromats, with a plan designation added to lenses with low curvature of field and distortion. This section addresses some of the more common optical aberrations that are commonly found (and often corrected) in microscope objectives.

Left: a microscopic view of the tilted facets in a typical blazed diffraction grating. Right: an illustration of the saw-tooth profile of a blazed reflection ...

Aberrations are divided into two main categories: errors that occur when polychromatic light (white light) is passed through a lens, and errors that are present when only a single wavelength (monochromatic) of light is utilized. The selected references listed in this section contain information about the cause and correction of the most common optical aberrations encountered with microscope and other lens systems. Bear in mind that the optical designer must correct for both polychromatic and monochromatic aberrations simultaneously in the production of well-corrected microscope objectives.

Seidelaberrations

X-ray images can be captured using digital radiography sensors. The most common type of such sensors are flat-panel detectors (FPDs) [6]. These detectors come in “direct” and “indirect” varieties. Similarly to conventional image detectors, direct FPDs convert X-ray light directly to charge (but use different materials), and the generated charge is read out by a pixel array. Indirect FPDs first use a scintillator to convert the incident X-rays to visible light, which is then measured by a pixel array.

Learn more about chromatic aberrations and how when white light passes through a simple or complex lens system, the component wavelengths are refracted according to their frequency.

Most images sensors are either charge-coupled devices (CCD) or complementary metal-oxide semiconductor (CMOS) arrays. These sensors operate using different electrical mechanisms and are fabricated by different methods, and as such they tend to each have their own advantages and disadvantages.

Finally, it is possible to generate an image of an object without using a pixel array-based sensor at all. Single-pixel cameras are a type of “camera” that operate by measuring (with a single photodiode, for example) the amount of light reflected from each of a series of patterns projected on the object. In the most straightforward case, the pattern is simply a focused point of light that is scanned over the surface of the object. By mapping the amount of reflected light to the location from which it was reflected, an image of the object can be inferred.

In cases where colour images are needed along with the advantages of a monochromatic sensor, alternative methods can be used. One method is to take individual red, green and blue images with a monochromatic camera using full-frame colour filters, and to reconstruct the true colours by combing the three images. Another method is capture RGB images simultaneously using three sensors with a special prism used to direct each colour range to one of the three sensors (sometimes called a 3CDD camera [5], though CMOS sensors could also be used).

Learn about comatic aberrations and how they are mainly encountered with off-axis light fluxes and are most severe when the microscope is out of alignment, as well as the result of when these aberrations occur.

Selecting and using a camera sensor in a medical device requires the consideration of many factors. In this blog series, we have discussed some of the most important aspects such as resolution, pixel size, dynamic range, exposure time, and frame rate, as well as the most common types of image sensors and their advantages and disadvantages. With proper attention to these factors, a camera sensor can be chosen and configured to produce the most high-fidelity images and/or cleanest data possible.

Learn about the most serious of the monochromatic defects that occurs with microscope objectives, the spherical aberration, which causes the specimen image to appear hazy or blurred and slightly out of focus.

A demonstration on how internal lens elements in a high numerical aperture dry objective may be correctly adjusted with these varied cover glass thickness and dispersion fluctuations is featured in this tutorial.

Colour camera sensors are useful because they provide a simple way to capture colour images. They can also be used to approximate a monochromatic camera sensor in software (for example, by only displaying data from the green channel, or by converting a captured image to greyscale). However, they have some disadvantages compared to monochromatic cameras, which are often the superior choice when colour is not needed.

In monochromatic cameras, the image is obtained simply by recording the amount of light captured by each pixel. In most colour cameras, an array of red, green and blue (RGB) colour filters (a Bayer filter) is placed over the pixels that restricts the light collected by each pixel to a certain range of wavelengths (colours)[1]. Based on the amount of light collected by each of the filtered pixels, the colour image is inferred based on the collected pattern, in a process called demosaicing [3].

Both of these words, optometrist and optician, are forms of the word "optic." Optics is the branch of physics that involves the study of light. People who ...

In CCDs, an array of photosensitive capacitive sites (i.e., pixels) each accumulate charge proportional to light incident upon them. After the exposure to light has been completed, a control circuit is used to move the charge from each pixel into a charge amplifier, which converts the accumulated charge into a voltage. Once the charge collected on each site has been measured, an image can be generated.