Double Ten science and technology about laser luminescence intensity measurement

Date:2022/8/2 8:55:27 / Read: / Source:本站

Double Ten science and technology about laser luminescence intensity measurement
The theoretical basis of luminescence intensity measurement is the inverse square law. Real light sources are not point light sources, but have
The luminous area of a given size. In general, the distance between the object and the light source is up to one! · Only when times are higher can we see points
The light source.
Photometric measurement methods include visual method and objective method. Helioscopic method is the direct participation of the human eye in the measurement process. The human eye to
There is a keen ability to judge whether the brightness of two adjacent surfaces is equal, and to judge their brightness in quantity
The difference is very difficult. All helioscopic measurements thus boil down to a comparison of the brightness of two faces
And balance it out. Various visual photometers are designed according to this feature. One of the most perfect is the Land End -
The Lummer-Brodhun Photometer is shown in Figure 4.12. On the right is the end of the land
The body. Its central part is made of two 450 right Angle prisms glued together with light glue. Carved on the slope of one of them
Etched into the pattern shown on the right of FIG. 4.13. The two sources to be compared illuminate diffuse surfaces Si and S2 respectively, and the field of view is
As you can see in the pattern on the right, the diagonal section and other sections are illuminated by Si and S2, respectively, so that both are illuminated by
The sides of comparison are juxtaposed to make it easier to compare their brightness.
The terminal cube consists of two rectangular prisms glued together, one of which is notched diagonally in a not too deep groove.
In this way, most of the light from the mirror passes through the cube to the eyepiece, and only A small part is reflected at A
To go out. The transmitted light and the reflected light form two adjacent images in the helioscope that do not interfere with each other, as shown in the lower right of FIG. 4.13
Shown below.
The shaded line and empty self represent the image of two different light sources. In the light path from the mirror, each piece is placed
The color transparent compensatory glass pieces are positioned to correspond to two small trapezoidal images in the helioscope field of view. such
The light is reduced by 8%, and the trapezoid is slightly darker than its surroundings, allowing a more accurate comparison of the two sources in the field of view
The intensity of illumination.
When adjusting the position of the light source 1 and the auxiliary light source 2 on the light holder to achieve photometric equilibrium, no
Only the boundary between the two semicircles disappears, and so does the boundary between the two trapezoids and the corresponding semicircle background.
If the distance between the light source 1 and the terminal cube is Q, and the distance between the auxiliary light source 2 and the cube is dX, then the eyepiece is considered
When the boundary disappears in the field of view, the intensity of light on both sides is equal, so it follows from the inverse square theorem
Change the light source 1 to the standard lamp, repeat the above steps, adjust the distance between the auxiliary light source 2 and the cube to be
Ds, available
This method of measuring luminescence intensity has a high degree of accuracy.
When the color temperature difference between two lamps is below iooK, it is easy to achieve photometric balance observation by visual method.
However, when the color temperature difference is above looK, due to the different colors of the images in the field of view, the photometric balance is achieved by the helioscopic method
Is more difficult to observe. In this case, a selenium photocell with a correction filter can be used instead of human visual vision to solve the problem smoothly
Overcome this difficulty.
For a standard lamp, the measured photocurrent is
This objective physical measurement is more accurate than visual measurement.
The visual method is mostly used to test the vision of the human eye, while photometric measurement uses the objective method, or physical receiver
Method. The receiver used in the objective method must be equipped with A V (A) correction filter, as shown in Figure 4.14. Its response is the same as
The received light flux or illuminance is directly related. Thus all photometric measurements using objective methods are reduced to optical flux
A measurement of quantity or illumination.
Photometric measurement, like radiometric measurement, is affected and interfered by many factors, so it is difficult to get high precision
Degrees. What is worth paying attention to is the degree of perfection of V(A) correction. The measurement system must be determined by a radiometric standard
Standard.
According to Kendra's new definition, photometric benchmarks can be reproduced in a number of ways. It's technically the best
The trick is to add A V (A) filter in front of the absolute radiometer so that it has the spectral sound of A standard photometric observer
Characteristics, as shown in Figure 4.15.
It is the actual irradiance measured by the radiometer after passing through the V(in) filter, and Till is the wave in the filter
555nm long transmission ratio.
A photometric reference consisting of A radiometer and A V(A) filter system is used to calibrate A set of color temperatures of 2
The luminescence intensity value of the standard lamp at 856K is used as the secondary standard, that is, the secondary reference of the luminescence intensity, and the unit is still the emission
A unit of light intensity -- Candela.
In practical work, it is often necessary to measure the total luminous flux emitted by the light source, so it is required to establish a corresponding meter
Quantity standards. The luminous intensity of a set of standard lamps with total luminous flux was measured according to the luminous intensity sub-reference with a distribution photometer
From which the total luminous flux emitted by a standard phantom is calculated as the relative luminosity (e.g., spherical luminosity)
The highest standard for measuring the total luminous FLUX of a light source, called the total luminous flux subreference. The secondary reference calibrates the corresponding work
As a reference, the working reference transmits the unit value maintained by the sub-reference to the standards at all levels for use in practical work
To use.
The luminous intensity standard lamp is also the illumination standard lamp. The light it builds up at a certain distance
Illuminance can be calculated according to the inverse square of distance rule and used to calibrate the illuminometer. When the light shines evenly
When reflecting surface, if the reflection ratio of diffuse reflecting surface is mouth, the illuminance on the surface is E, then its brightness is
Therefore, luminance can be calibrated by illuminating a standard diffuse reflector plate with a known diffuse reflectance ratio with a luminescence intensity standard lamp
, as shown in Figure 4.16.

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