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FOV tofocal length
Doctor, 2022. Vision doctor, home page. https://www.vision-doctor. com/en/. (A private, independent, non-commercial website project providing solutions to machine vision. Accessed on 4.5.2022).
Note that SAPO and XAPO are Evident's original names that indicate the grade of chromatic aberration. Detailed definitions of ACH, FL, and APO are described in ISO, so please refer to ISO19012-2.
Focaldistance vsfocal length
Makoto Kuwano has been in charge of microscope product development for 12 years at Evident. He currently works in the Optical Development Division, where he is involved in optical design of objective lenses, development of component products, and development of measurement techniques for product performance. He holds a Master of Science degree from Tohoku University in Japan.
The code M stands for metal, and it is an objective lens for observation without a cover glass. In addition, the following codes are used according to the length of the working distance and optical performance.
While there are many parameters to consider, the infrared (IR) cut and possible colour corrections are the least worth mentioning features. Suppose an imaging system is for spectral imaging, and the interesting wavelength range is in IR. It might be good to exclude lenses designed to block IR light or lenses that have some other undesirable colour corrections by default (Greivenkamp 2004; Stemmer 2022).
In this post, we’ll share how to read the optical performance from the name of a microscope objective so that you can easily find the correct objective lens for your application. As our objective lenses for life science and industrial applications have different naming rules, we’ll discuss how to read the specifications for each field.
We hope this list of microscope objective specifications was helpful! Be sure to bookmark it for easy reference when selecting an objective lens. If you are unsure about choosing an objective lens or have any questions, feel free to contact us. We can help you select the best objective based on factors such as sample type, imaging technique, numerical aperture, and desired magnification.
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The relation between the opening angle and focal length is the opposite; the larger the focal length, the narrower the opening angle. Most of the lens parameters described in Table 2 (Post 3.1) can be calculated either with pen and paper or using services like Vision Doctor (Doctor 2022) or sensor manufacturers’ web tools, which are provided for designing imaging systems.
*The objective may work with other observation methods not expressed in the code, including brightfield (reflected), brightfield (transmitted), darkfield (reflected), darkfield (transmitted), DIC (reflected), DIC (transmitted), phase contrast, relief contrast, polarization, fluorescence (B/G excitation), UV fluorescence (at 365 nm), multiphoton, total internal reflection fluorescence microscopy (TIRF), and infrared (IR). Please refer to our website for the full objective specifications.
*The objective may work with other observation methods not expressed in the code, including brightfield (reflected), brightfield (transmitted), darkfield (reflected), darkfield (transmitted), DIC (reflected), DIC (transmitted), phase contrast, relief contrast, polarization, fluorescence (B/G excitation), UV fluorescence (at 365 nm), multiphoton, total internal reflection fluorescence microscopy (TIRF), and infrared (IR). Please refer to our website for the full objective specifications.
ACH = achromat. Excellent correction of chromatic aberration in two colors (blue and red). FL = semi-apochromat. Excellent correction of chromatic aberration in three colors (blue, green, and red). APO = apochromat. Corrects the chromatic aberration of three colors (blue, green, and red) better than FL.
Like the life science objectives, industrial objectives marked PL or Plan are corrected for field curvature at the periphery of the field of view. This objective type is particularly suitable for imaging because it can focus not only on the center of the field of view but also on the periphery. This enables you to obtain a flat image from the center to the edge.
Our website provides a wide range of technical content and product information about our microscope objective lenses. For more details, simply refer to the following links:
The working distance, object size and focal length affect the magnification. From above, Figure 15, we can see that a longer focal length increases the magnification without extending the working distance a. Magnification β can be approximated for a non-complex optical setups as follows (Greivenkamp 2004):
Focal length
U = universal objective lens. This objective lens achieves a high level of basic performance in terms of both differential interference performance and fluorescence performance capable of U excitation. It can be used for brightfield observation and fluorescence observation by blue/green (B/G) excitation, as well as for differential interference contrast (DIC) observation and fluorescence observation by U excitation.
This is where microscope objective specifications come in. These specifications tell you the optical performance, such as magnification, aberration correction, and other parameters. You don’t have to look far to find them—in fact, our specifications are listed as a code within the objective lens name! This makes it easy to distinguish between objective types at a glance.
This code indicates whether it is a dry objective lens used for observation without immersion liquid or an immersion objective lens for observation using immersion liquid. In the case of immersion objectives, the liquid used is represented by the symbol O for oil or W for water.
Stemmer 2022. Stemmer Imaging, The Imaging and Vision Handbook. URL:https://www.stemmer-imaging.com/en/the-imaging-vision-handbook/.
DIC observation* is possible due to features such as the pupil position that matches the microscope system from Evident. In addition, it has good transmittance at 365 nm (the U excitation wavelength) and has low autofluorescence, enabling fluorescence observation by U excitation.
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The correction range for chromatic aberration in objectives differs for each code. The level of chromatic aberration improves in the order of ACH, FL, APO, SAPO, and XAPO. If chromatic aberration is well corrected, sharp fluorescence images with no out-of-focus areas can be obtained for each color even in multicolor observation using fluorescent reagents covering a wide band.
Focal length (FL) affects the field of view and magnification, as it is one of themost important parameters when choosing optics.
Focal lengthtomagnificationcalculator
Objectives with PL or Plan are corrected for field curvature at the periphery of the field. This objective type is particularly suitable for imaging because it can focus not only on the center of the field of view but also on the periphery. This enables you to obtain a flat image from the center to the edge.
The correction range for chromatic aberration differs for each code. There are three types, ACH, FL, and APO, and the chromatic aberration performance is defined in the same way as the objective lenses for life science.
L = long working distance objective lens. This is an objective lens with a long working distance (the distance from the tip of the objective lens to the specimen surface when focused). In general, there is a trade-off between resolution and working distance. If you want space between the objective lens and the sample, or if you want to observe deep parts, give priority to working distance over resolution.
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Below, Figure 2 explains the lens opening angles and their relations with the horizontal, vertical and diagonal field of view (FOV). By looking at the angles and rays of the image, we can see that the relation between the field of view and working distance correlates; the image field of view decreases while the working distance shortens and vice versa.
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For life science, we’ll use the objective lens called UPLXAPO100XOPH as an example. You can understand the optical performance from the objective lens name by dividing the name into six parts, 1 through 6. Below is an overview, and we’ll explain each part in the following six sections.
focallength中文
We will use the MPLFLN100XBD objective lens as an example in the industrial field. Note that some of the specifications are the same as those of objective lenses for life science. For industrial objectives, you can understand the objective lens name at a glance by dividing it into five parts, 1 through 5.
In addition to the name of the objective lens, information on the numerical aperture (NA), magnification, cover glass thickness, immersion liquid, and objective field number (OFN) is provided on the exterior of the objective lens. Below is an example of the UPLXAPO100XO objective that explains how to read these specifications.
The number before the X represents the magnification of the objective when combined with a tube lens from Evident with a focal length of 180 mm. Evident offers objectives with magnifications ranging from 1.25–150X.
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M = metal (no cover) LM = long working distance for metal SLM = Super long working distance for metal MX = high NA and long working distance for metal
ACH = achromat. Excellent correction of chromatic aberration in two colors (blue and red). FL = semi-apochromat. Excellent correction of chromatic aberration in three colors (blue, green, and red). APO = apochromat. Corrects the chromatic aberration of three colors (blue, green, and red) better than FL. SAPO = super apochromat. Good correction of chromatic aberration in the visible to infrared range (435 to 1000 nm). XAPO = extended apochromat. Good correction of chromatic aberration in the visible to infrared range (400–1000 nm).
Objective lenses are crucial to a microscope’s performance as they affect the quality of the formed image. Evident offers more than 200 types of objective lenses to suit a wide range of imaging requirements in life science and industry. With so many options available, you might be wondering which objective is best for your work.
Focal length refers to the distance between the main plane of the lens and a particular point where the light is focused from infinity. Below, Figure 1 visualises how the focal length, marked with f and f ′, affects the image height. A long focal length magnifies more than a short one (Greivenkamp 2004).
Just like the life science objectives, the number before the X in industrial objectives represents the magnification of the objective when combined with a tube lens from Evident with a focal length of 180 mm. Evident offers objectives with magnifications ranging from 1.25–150X.