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The two most important parameters of optical glass in general are what you call the nd and abbe constants. Nd is the refractive index at a standard wavelength, while the Abbe constant refers to the dispersion parameter of the glass. To quote the first floor, "The physical definition of Abbe's dispersion coefficient is (nd-1) (nf-nc)."

The above equation Nd is the refractive index of 587nm (yellow-green) light, NF is 486nm (blue light) refractive index, and NC is 656nm (red light) refractive index. It reflects the dispersion of a material, and the larger the ABBE coefficient, the smaller the dispersion. There are hundreds of general optical glasses, most of which are between 25 and 90.

The second question, the relationship between the nd and the abbe constant, I don't think there is any special correlation between the two, because the mechanisms that cause the refractive index and dispersion are completely different. However, for a particular model of glass, there is a pattern in the relative relationship between them. Now there are two kinds of optical glass commonly used, one is called crown glass and the other is called flint glass.

The characteristics of crown glass are that the nd is small and the abbe constant is large, while the flint glass is large and the abbe constant is small. It depends on the type of glass.

Visible light selection 1200 infrared selection 90 strips.

Restricted by diffraction, d; Considering the range of free light old virtual dust spectrum, the first-order diffraction and the second-order diffraction should not overlap, just half of the difference, so the free spectral range is 1 2d d.

It can be seen that 1200:d 800nm; 90: Acolyte D 10 m

/2 / l = d / l

d = mm

Move in the direction of the ridge line town mausoleum;

The stripes at the wire move 9 stripes, 9 * 2 = mm, that is, the diameter of the wire increases and the number of mm is added. Imperial Rules.

This is caused by the reflection of light, because your child's image is projected, hugging the mirror, and then reflected back into your eyes, so you can see a lower image than the girl you meet.

Because your viewing angle is very high, you look down in the mirror, so you can see the baby who is lower than the mirror, and if the mirror is lower, you can see the ground.

Because what you see is a reflection of the mirror, and you can usually see that position.

There is light shining on the baby, and then the light shines on the mirror, and the reflection of the light enters his own eyes. (The incident light and the reflected light are at the same angle from the mirror).

Mirror imaging is formed by the reflection of light.

The reflection theorem states that the incident and reflected rays are located on either side of the normal, and the angle of reflection is equal to the angle of incidence.

Because the baby is lower than the mirror, the incident light from the baby should be tilted upwards to enter the mirror. That is, the angle of incidence is below the normal.

If your eyes are high, then the reflection angle coming out of the mirror is just above the normal. As long as the angle of reflection of the light entering your eyes is equal to the angle of incidence, you can see the baby's image.

If the eye is positioned low (so that the angle of reflection is less than the angle of incidence), the baby's image will not be visible.

The height seen by the two is different, and for the cube "straight down" is a potential condition (sina tana!).Because a 0), and the hemisphere passes through the point of the ball because of the ignorance of the incident lead, h2=d! Let the height of the dotted point be h1 and h2 respectively, for h1 then tana=x (d-h1), x is the distance between the extension line of the incident ray and the vertical upward extension line of the intersection of the refracted ray and the ground, so h1 hopes to help you.

The diffraction of the small round screen is symmetrical, and it can also be regarded as the interference of the opposite sides of the diameter of the disk, and the larger the radius, the larger the d, the larger the diffraction radius.

Red, black. Because the color of a transparent object is determined by the color light transmitted, the thermometer liquid is red and red under red light, whereas the glass of a thermometer is transparent and will pass through red light and will look red as well. It's all red, it's very difficult to read, and you can't even read out the data.

The blue color only transmits blue light, and the other colors cannot be transmitted, and it is displayed as black, which contrasts with the glass and is easy to read.

Good luck.

1. (Red) Because red liquid can absorb different colors of light and reflect the same color of light, transparent glass is also red under red irradiation (transparent physical color is determined by the color light it transmits), so it will not be able to see the temperature.

2. (Black) Because the blue liquid absorbs different colors of light (red light is absorbed), no color light is reflected, so it is black.

Red liquid with black scales.

After natural light a passes through polarizer 1, the light intensity becomes yes, and after passing through 30° polarizer 2, the light intensity is * cos(30) 2 = ;

For natural light b, it is after polarizer 1 and = after polarizer 2 at 60°;

So the ratio of natural light intensity a:b = 1:3

It is easy to solve with Marius's law.