# Olympus microscope FAQ

- Apr 15, 2020-

Q: Express the problem

A: Indicate the answer.

Q: What is numerical aperture na?

A: Numerical aperture is the main technical parameter of objective and condenser, and it is an important sign to judge the performance of them (especially for objective). The higher the numerical aperture is, the higher the edge ratio is and the smaller the focal depth is.

Q: Is it possible to use an objective lens with a finite barrel length on an infinite optical system?

A: You may be able to screw the objective lens onto the objective turntable, but due to the relationship between the image forming lens on the optical path of the infinite optical system, the objective lens using the finite far system cannot get the Zui good image.

Q: Is it possible to use the objective lens of an infinite system on a microscope with a finite cylinder length?

A: No. Because the image finite far optical system does not contain a junction lens which can focus the parallel light path on the optical column surface of the eyepiece.

Q: Can the phase difference objective be used for other observation methods?

A: Yes, yes. Only by moving the diffractive condenser to the "0" position, the diffractive objective has a phase plate on the back focal plane, but most of the light is not affected by this phase plate. Therefore, the image quality is only slightly affected, and it is still useful for the bright field image. The phase contrast objective made by Olympus can also be used for fluorescence observation.

Q: What is the meaning of Ph1, pH2 and PH3 marked on the phase difference objective?

A: The phase difference objective lens shall be used together with the annular diaphragm installed in the condenser. The diameter of the diaphragm should match the Na value of the objective lens. For the objective lens of Olympus UIS, Ph1 means that the Na value of the objective lens does not exceed 0.50; pH2 means that the Na value is between 0.55 and 1.0; PH3 means that the Na value is greater than 1.0 (oil lens). Long working distance objective lens uses special phase difference ring.

Q: Can high NA objective be selected for video microscopy to observe the details of micro specimens?

A: Yes, yes. Glare may darken the details of the image when you look through the eyepiece, but necessary information is often included in it, so video enhancement technology can process this information and obtain excellent video image.

Q: Should I buy as many lenses as I can afford?

A: Usually, but not always. If the thickness of the specimen you are looking at is a few microns, flat field achromatic or flat field half achromatic lenses are good because they have a better focal depth than flat field achromatic lenses. If it is used in color photography, the flat field half apochromatic aberration is better than the image obtained by the flat field apochromatic objective. Flat field achromatic objective can obtain excellent observation and photographic effect in small details, but it often costs several times more than flat field achromatic objective.

Q: How to avoid 40 times damage of dry objective lens when dropping oil?

A: If you often use a 100x oil mirror, you may want to replace a 40x dry mirror with a 50x oil mirror. The 50 times flat field achromatic oil mirror (na0.90) is brighter and clearer than the standard 40 times flat field achromatic or achromatic dry mirror (na0.65).

Q: How to reduce asphalt on 40 times dry mirror?

A: When you are converting 40 times dry mirror and 100 times oil mirror, try to avoid 40 times dry mirror soaking in oil. The laboratory often places the two lenses in opposite directions

Q: Why is the imaging effect of 40 times objective lens worse than 20 times?

A: When the thickness of the specimen is 0.17mm greater than the standard thickness, or there are other substances on the cover glass. In order to improve the imaging effect, you can use the dry objective with correction ring, or replace the 40 times dry objective with 40 times and 50 times oil lens, because the oil immersion objective is less sensitive to the change of cover glass thickness.

Q: How to use flat field achromatic objective in fluorescence observation?

A: Flat field achromatic objective is suitable for blue and green excitation wavelengths. The glass tension of flat field achromatic objective can be excited to near ultraviolet. Therefore, the numerical aperture of flat field chromatic aberration objective is lower than that of flat field half complex or flat field chromatic aberration objective, so it needs a dimmer.

Q: How large is the numerical aperture of the "dry" objective lens (air is used as the medium between the front lens and the cover glass)?

A: The numerical aperture of the dry objective can reach 0.95, but the correction ring is needed to observe the cover glass.

Q: Why does the "dry" 20x, 40x and 60x objective have a correction ring?

A: Rotating the correction ring can make the distance of the lens group in the objective lens, so as to correct the spherical aberration caused by the too thick cover glass. In an upright microscope, the correction cover glass range of the correction ring is 0.11mm to 0.22mm. In the inverted microscope, the correction range is 0 to 2mm.

Q: Why does a 20x objective or higher have a spring or a retractable front-end lens?

A: Generally, the working distance of the objective lens is relatively short. If the front end of the objective lens is used carelessly, it will touch the slide or sample. The spring device installed in front of the lens can prevent the sample from being touched during use. If not installed correctly, protect in the opposite direction and rub continuously.

Q: What does "PL" or "NH" mean on the phase difference objective?

A: "PL" stands for "positive low" and "positive difference". It means that the index is darker than the surrounding environment, i.e. the dark in the bright. It is suitable for the tested object with weak refractive index. "NH" stands for "negative high", is a negative difference, and is the indicator that is brighter than the surrounding environment, that is, brighter in the dark. It is suitable for the object with weak refractive index.

Q: Why need UV objective?

A: The lens group of UV objective lens adopts a new coating process design, so that it can penetrate the light of near UV wavelength, while the ordinary objective lens can not reach, this objective lens is used for UV fluorescence excitation work. The new Olympus infinite correction flat field re correction objective and half field re correction objective have greatly improved the performance of near UV observation.

Q: Why is the "NIC" or "DIC." mark on the objective lens?

A: These things