4.2 Spectral Black Marking Pre-production with Two Steps Rainbow Holography
The two-step rainbow hologram production was completed in two steps.
4.2.1 First make the master hologram. The optical path design is shown in Figure 4.1:
The two-step rainbow hologram production was completed in two steps.
4.2.1 First make the master hologram. The optical path design is shown in Figure 4.1:
The light emitted by the He-Ne laser is split by the HM beam splitter: a beam is reflected by the total reflection mirror W2, L1 expands to form a spot-illuminated object, and is reflected by W1 to become object light; the other beam expander L2, collimating lens L3, forming a parallel reference light illuminates onto the dry plate W2 to interfere with the object light to obtain a master hologram.
When the master hologram is produced, the ratio of the light intensity of the object light to the reference light is ideally 1:3. When the light intensity ratio is too small, the diffraction effect is not good, and the image is not clear; the light intensity ratio is too large, the reference light is severely attenuated, the light spot is uneven, and the image is blurred.
The smaller the optical path difference between the object light and the reference light, the better. The maximum cannot exceed 20 cm.
Specific experimental operations and data are as follows:
The experimental steps are:
1 Adjust the light path diagram as shown in Figure 4.1.
2 Turn on the laser and wait for a while.
(3) After the laser is stabilized, detect the light intensity of the object light and the reference light with a photocurrent detector, calculate the light intensity ratio, measure several times, and record the data.
4 Measure the optical path of the object light and the reference light, calculate the optical path difference, and record the data.
5 Block the laser and cut the dry plate under dark room conditions.
6 Install the dry plate and expose it in 1 minute, 2 minutes, and 3 minutes respectively.
7 Pack dry version, configure each darkroom reagent according to the above formula.
8 The darkroom operation resulted in a master holographic dry plate. The main hologram is obtained after developing → stopping the display → rinsing → fixing → rinsing → bleaching → rinsing → drying. The development temperature is 20±0.5° C., and the development time does not exceed 3 minutes. The developer is constantly agitated during the development process. Take out the dry version from the developer and apply tap water. Rinse the developer and put it in the stoppage liquid for 20-30 seconds. Stop the liquid temperature at 19-20°C. After the version is stopped, it can be fixed in the fixing solution. The fixing solution temperature is 19-20°C and the fixing time is 2-4 minutes. During the fixing process, the fixing solution should be continuously agitated. The fixed plate is rinsed in water at 18-21°C for 10-20 minutes, then bleached until the plate turns white, and rinsed and dried.
The data record is as follows:
Table 4.5 Master holographic production data
When the master hologram is produced, the ratio of the light intensity of the object light to the reference light is ideally 1:3. When the light intensity ratio is too small, the diffraction effect is not good, and the image is not clear; the light intensity ratio is too large, the reference light is severely attenuated, the light spot is uneven, and the image is blurred.
The smaller the optical path difference between the object light and the reference light, the better. The maximum cannot exceed 20 cm.
Specific experimental operations and data are as follows:
The experimental steps are:
1 Adjust the light path diagram as shown in Figure 4.1.
2 Turn on the laser and wait for a while.
(3) After the laser is stabilized, detect the light intensity of the object light and the reference light with a photocurrent detector, calculate the light intensity ratio, measure several times, and record the data.
4 Measure the optical path of the object light and the reference light, calculate the optical path difference, and record the data.
5 Block the laser and cut the dry plate under dark room conditions.
6 Install the dry plate and expose it in 1 minute, 2 minutes, and 3 minutes respectively.
7 Pack dry version, configure each darkroom reagent according to the above formula.
8 The darkroom operation resulted in a master holographic dry plate. The main hologram is obtained after developing → stopping the display → rinsing → fixing → rinsing → bleaching → rinsing → drying. The development temperature is 20±0.5° C., and the development time does not exceed 3 minutes. The developer is constantly agitated during the development process. Take out the dry version from the developer and apply tap water. Rinse the developer and put it in the stoppage liquid for 20-30 seconds. Stop the liquid temperature at 19-20°C. After the version is stopped, it can be fixed in the fixing solution. The fixing solution temperature is 19-20°C and the fixing time is 2-4 minutes. During the fixing process, the fixing solution should be continuously agitated. The fixed plate is rinsed in water at 18-21°C for 10-20 minutes, then bleached until the plate turns white, and rinsed and dried.
The data record is as follows:
Table 4.5 Master holographic production data
Optical Reference Light Path Difference and Light Intensity Ratio Optical Path (cm) 130120 Δ=10 Light Intensity 14.855.81:3.7715.258.01:3.81 Angle of Incident Light and Reference Light <300
After the master hologram is completed, the flushed image should be able to receive a clear real image under the parallel laser beam before the two-step rainbow hologram can be continued.
4.2.2 Select a master hologram with a clearer image Make a two-step rainbow hologram.
4.2.2 Select a master hologram with a clearer image Make a two-step rainbow hologram.
The optical circuit design is shown in Figure 4.2:
When making a rainbow hologram, you should control the following parameters:
S slit width d, generally should be d = 6mm, S to dry plate distance W1, generally should be controlled within 80mm, adjust the angle of K, control the light intensity ratio of 1:2, reference light and object light The angle should be controlled within 30° and the exposure time should be controlled within 2 minutes.
Specific experimental operations and data are as follows:
The experimental steps are:
1 Adjust the light path as shown in Figure 4.2.
2 Adjust the distance d between the slit S and the master hologram and record the data.
3 Turn on the laser and wait for a while.
4 After the laser is stabilized, measure the ratio of light intensity and record the data.
5 Measure the optical path of the object light and the reference light, calculate the optical path difference, and record the data.
6 Expose the plate in darkroom conditions for 2 minutes and experiment multiple times.
7 W2 wrap dry W2 in black paper and store it to prevent accidental exposure.
The data record is as follows:
After the rainbow hologram is made, it can be encrypted according to the design light path of the holographic spectrum secret light path (Figure 4.3), except that it is an exposed but undeveloped two-step rainbow hologram. (To be continued)
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