What is the difference between metallographic microscope darkfield and polarized light 20

How to use polarized light in a metallurgical microscope?

Polarized light microscopy is a microscope that identifies the optical properties of the fine structure of a substance. All substances with birefringence can be clearly distinguished under a polarizing microscope, of course, these substances can also be observed by dyeing, but some are not possible, and a polarizing microscope must be used. Polarizing microscopy is a method of microscopic examination by changing ordinary light into polarized light to distinguish whether a substance is monorefringent (isotropic) or birefringent (anisotropic).

First of all, it should be clear that the metallurgical microscope can also be equipped with polarization accessories, which is what we often call simple polarization, specifically referring to polarizers and polarizers, as shown in the figure below

Polarizer <>

Detector. <>

So how do you use these two accessories?

1) Insert the polarizer separately, that is, single polarization, mainly to observe the morphology, cleavage, color, protrusion, rough surface, Baker line and other phenomena of minerals.

2) Insert the polarizer and polarizer at the same time, which is what we usually call polarization, then we can turn the polarizer knob to adjust the polarization angle;

3) Under the condition that the polarizer and detector are inserted at the same time. When the polarized light is adjusted to 90°, it is orthogonal polarization.

The above is provided by Linktour Instruments.

Light in brightfield is direct and reflected back, making it difficult to see details such as minor damage and scratches. The light path of the dark field is blocked in the middle, leaving only the ring light obliquely hitting the object, and the details of the small damage can be highlighted.

(1) Effectively improve the microscope identification rate; (2) Improve the contrast of the microscope; (3) Non-metallic inclusions can be identified.

Observe subtle objects that are not visible in brightfield. Higher resolution than brightfield.

It depends on what kind of effect you want to see, brightfield means that the image of your product is the same as the product itself, there is no color, if you use darkfield, that is, the company you want to see is bright, and other places are dark, this is the advantage of metallurgical microscope! Generally, it is relatively small, and it is recommended to use dark field, which is more obvious. I don't know if my answer will be useful to you.

This has something to do with the sample you are observing, and it doesn't mean that high-end metallographic microscopes are all light and dark fields!

It depends on what kind of effect you want to see, brightfield means that the image of your product is the same as the product itself, there is no color, if you use darkfield, that is, the company you want to see is bright, and other places are dark, this is the advantage of metallurgical microscope! Generally, it is relatively small, and it is recommended to use dark field, which is more obvious. I don't know if my answer will be useful to you.

Polarized light should be used, and dark field should be used less! However, most metallurgical microscopes have polarizing devices!

When light penetrates the surface of an optical element, such as a beamsplitter, at a non-perpendicular angle, both the reflection and transmission properties depend on the polarization phenomenon.

In this case, the coordinate system used is defined in the plane that contains the input and reflected beams. If the polarization vector of the ray is within this plane, it is called p-polarization, and if the polarization vector is perpendicular to that plane, it is called s-polarization. Any kind of input polarization state can be expressed as the vector sum of the s and p components.

When light penetrates the surface of an optical element, such as a beamsplitter, at a non-perpendicular angle, both the reflection and transmission properties depend on the polarization phenomenon.

In this case, the coordinate system used is defined in the plane that contains the input and reflected beams. If the polarization vector of the ray is within this plane, it is called p-polarization, and if the polarization vector is perpendicular to that plane, it is called s-polarization. Any kind of input polarization state can be expressed as the vector sum of the s and p components.

Experimental methods are used to distinguish natural light, linear polarization as collapse light, circularly polarized light, elliptical pure rock circular polarized light and partially polarized light method

1. Equipment: polarizers, jujube blind 1 4 slides.

Second, the specific steps:

1.If the light intensity does not change with the rotation of the polarizer, the beam of light is natural or circularly polarized. At this time, put 1 4 slides before the polarizer and then rotate the polarizer.

If the intensity still does not change, it is natural light; If there are two extinctions, it is circularly polarized because 1 4 slides can change circularly polarized light into linearly polarized light.

2.If the light intensity changes with the rotation of the polarizer but does not extinct when observed with a polarizer, the beam is partially polarized or elliptically polarized. At this time, the polarizer can stay at the position with the greatest transmitted light intensity, insert 1 4 slides in front of the polarizer, make the optical axis of the slide parallel to the projection direction of the polarizer, and if the polarizer is rotated again, there will be two extinctions, that is, elliptical polarized light, that is, the elliptical polarizer becomes linearly polarized light; If there is still no matting, it is partially polarized.

3.If there are two extinctions with the rotation of the polarizer, the light is linearly polarized.

Partially polarized light is a situation between polarized light and natural light, and this kind of light contains both natural light and polarized light. In general, only oak, partially polarized light can be seen as a mixture of natural light and linearly polarized light. In nature, a lot of the light I see is partially polarized, and the "sky light" that I see when I look up and the "lake light" that I see when I look down are partially polarized light.

The light vector e of elliptically polarized light rotates uniformly around the direction of propagation while moving along the direction of propagation of light. The magnitude of its light vector changes constantly, causing its endpoints to depict an ellipse.

Ellipsically polarized light is a fully polarized light, while partially polarized light is not.

The metallographic microscope is to look at the general outline of the plane, analyze the organization, and look at the ordinary microscope that shows that it is missing, but it only observes the plane, and there is no data recording on the z-axis, and the accuracy of the research pole is relatively high, and there is a data acquisition on the z-axis, which can accurately measure the height and length.

The configuration of research-grade metallurgical microscopes will be higher!