Spectrometer, grating, mercury lamp spectrometer, grating, mercury lamp.

Third, the experimental principle and process:

1. Diffraction gratings and grating constant gratings are composed of a large number of parallel slits (or notches) with equal width and equal spacing. 1. Diffraction grating and grating constant grating are composed of a large number of slits (or notches) with parallel width and offset. Its schematic diagram is shown in figure 1. This figure is shown in figure 1.

If the groove width on the grating is a and the groove spacing is b, then d = a, 10 b is called grating constant, which is one of the basic parameters of grating. If the notch width of grating is a and the notch distance is b, then d = a 10 b is called grating constant, which is one of the basic parameters of grating.

2. Grating equation and grating spectrum According to Fraunhofer grating diffraction theory, when a beam of parallel monochromatic light is vertically incident on the grating plane, the light wave will be diffracted, and the diffraction angle satisfies the grating equation: 2. Grating equation, grating spectrometer grating According to Fraunhofer diffraction theory, when a parallel monochromatic light is vertically incident on the grating plane, the light will be diffracted, and the diffraction angle here satisfies the grating equation:

(1), the light will be strengthened. (1), the light will be enhanced. Where λ is the wavelength of monochromatic light and is a series of bright stripes. The formula of monochromatic light wavelength λ is the next fringe series. After the diffracted light waves are converged by the lens, a series of symmetrical bright stripes will be formed on the focal plane, as shown in Figure 2. After the diffracted light is converged by the lens, a series of symmetrical stripes will be separated on the focal plane, as shown in Figure 2.

If the incident light wave contains several kinds of polychromatic light with different wavelengths, after grating diffraction, the bright stripes of the same light with different wavelengths will be arranged in a certain order to form color spectral lines, which is called the diffraction spectrum of the incident light source. If the light shot by people contains polychromatic light with several different wavelengths, then through the diffraction grating, the light with these different wavelengths will form a color spectrum with a certain order of stripes specified by a (), which is called the spectral difference of the incident light source. Fig. 3 is the first-order diffraction spectrum of a common low-pressure mercury lamp. Fig. 3 is a common low-pressure mercury lamp with first-order differential spectrum. Each spectrum has four characteristic lines: purple λ1= 4358; Green λ 2 = 5461; Yellow two λ 3 = 5770, λ4=579 1. Each spectrum has four characteristic lines: purple λ1= 4358; Green λ 2 = 5461; Yellow 2λ 3 = 5770 and λ 4 = 579 1.3. Grating constant and wavelength of characteristic spectral line of mercury lamp can be measured by equation (1). If the light is vertically incident on the grating and the wavelength λ 1 in the first-order spectrum is known, the corresponding diffraction angle can be measured as 0, and the grating constant d can be calculated. On the other hand, if the grating constant is known, the wavelength of each characteristic spectral line emitted by the light source can be measured by equation (1). 3. The grating constant and the characteristic line of mercury wavelength measurement are known from the equation (1). If the incident light is perpendicular to the grating and the first wavelength λ 1 order spectrum is known, then the grating constant d can be calculated by measuring its corresponding diffraction angle; On the other hand, if the grating constant is known, the emission wavelength of the characteristic line can be measured from (1). You can use a spectrometer to measure the angle. Measure the angle with a spectrometer.

4.4. Experimental contents and steps A. Adjustment of spectrometer and observation of diffraction spectrum of mercury lamp (1) Adjust spectrometer. A. Adjustment of experimental contents and steps of spectrometer and adjustment of mercury diffraction observation (1) spectrometer.

(2) As shown in Figure 4, place the grating on the platform. (2) As shown in Figure 4, the grating is placed on the loading platform. By leveling screws or making the grating plane perpendicular to the optical axis of the collimator. Through the lever screw, the left and right grating plane and vertical axis collider. Then loosen the brake screw of the telescope, turn the telescope and observe the diffraction spectrum of the mercury lamp. The zero in the middle is white. When the telescope rotates left and right, four independent color spectral lines can be seen. Loosen the telescope brake screw, rotate the telescope diffraction spectrum mercury lamp, the center () and zero point are white, and turn the telescope to the left and right sides to see four color separation lines. If it is found that the left and right spectral lines are not on the same horizontal line, the two spectral lines can be on the same horizontal line by leveling screws. If it is found that the left and right sides of the spectral line are not on the same horizontal line, the leveling screw can make the spectral lines on both sides on the same horizontal line.

(3) Adjust the slit width of the collimator. (3) Adjust the width of the slit of the collider. The width of the slit should be able to distinguish two yellow spectral lines close to each other. The width of the slit shall be subject to the fact that two close yellow lines can be distinguished.

B. Measurement of grating constant and spectral wavelength (1) Take the wavelength λ=546 1 of the green spectral line as known, and measure the diffraction angle of its first-order () spectrum. B. Measurement of grating constant and spectral wavelength (1) The green spectral line with wavelength λ = 546 1 is known, and the divergence angle of its first-order () spectrum is measured. To eliminate eccentricity, the lower cursor and the lower cursor should be read at the same time. In order to eliminate the deviation difference, two cursors should also be read. Write it down, write it down. On the record, on the record. There is a measure. Be measured * * * Repeat the measurement three times. Repeat the measurement three times.

(2) The grating constant calculated by green spectrum measurement is known. (2) Calculate the measured values of green spectrum with known grating constant. Measure the angles of purple and two yellow spectral lines respectively according to the above steps, and repeat the measurement for three times. As mentioned above, there are two yellow and purple lines on the corner, and the measurement is repeated three times.

4. Experimental data processing and error calculation: 4. Experimental data processing and error calculation;

1. 1. data record t1t1t-1φ data record t1t/kloc-0.

Purple 93 14' 273 14' 7817' 25817' 7 28.5' purple 9314' 27314'

Green 95 8' 27510' 76 24' 256 24' 9 22.5' green 95 8' 275/kloc-0' 76 24' 256 24' 9 22.5'

Huang195 42' 275 43' 75 52' 255 53' 9 55' Huang195 42' 275 43' 75 52' 255 53' 9 55'

Yellow 2 95 45' 275 45' 75 50' 255 50' 9 57.5' Yellow 2 95 45' 275 45' 75 50' 255 50' 9 57.5'

2.2. See the above table for calculation. Calculation, see the table above.

3. Calculate the grating constant. 3. Calculate the grating constant.

d=3.3503μm

4. Calculate separately. 4. Calculated. Green is known as λ 1. According to the formula, sum, and are calculated respectively, and compared with the identification value, which is expressed as percentage error. Green is a known value of λ 1, which is calculated respectively according to the formula, and compared with the acceptable value, and expressed by percentile error.

=4355 E=0.069% = 4355 E = 0.069%

= 5763 E = 0. 13% E = 0. 13%

= 5796 E = 0.087% E = 0.087%

Verb (abbreviation of verb) Expression of experimental results and discussion of errors: 5. Expression of experimental results and errors;

d=3.3503μm

=4355 3 E=0.069% = 4355 3 E = 0.069%

= 5763 7e = 0. 13% = 5763 7e = 0. 13%

=5796 5 E=0.087% = 5796 5 E = 0.087%

Error source: 1, the grating spectrum is not strictly aligned with the reticle of the spectrometer; Error source: 1, grating spectrometer and spectrometer reticle are not strictly crossed;

2. When the scale value of the cursor is 1', the reading preference may cause an error of 1', especially it is difficult to distinguish two closely adjacent yellow spectral lines; 2. The cursor segmentation value is an error of "there may be one reading preference", especially it is difficult to distinguish two close yellow lines;

3. Calculate the transmission error of process data; 3. Calculation error of data transmission selection;

4. Errors caused by the limited precision of grating and spectrometer. Grating spectrometer and other instruments limit their precision errors.