The experimental system used for the original holographic recording generally includes a shock-absorbing holographic stage, optical path diverter, beam splitter, beam expander, collimator, imaging lens, Fourier transform lens, pinhole filter, dry plate frame, reset frame, Shutter, auto exposure and display fixing timer, multi-degree of freedom trimmer, variable light bar and other components. Holographic table The hologram is a record of the interference fringes of the reference wave and the object light wave. If the optical path difference of the two light waves changes during the exposure process, the modulation degree of the interference fringe will be affected. It is generally required that the change in the optical path difference is less than one-tenth. Therefore, in the production process of the original hologram, special attention should be paid to the stability of the holographic table. Factors that affect stability include vibration, air flow, and heat changes. The main impact of the vibration comes from the vibration of the foundation. If the mechanism of the recording system components is loose, the vibration will be amplified, so it is necessary to take vibration reduction measures on the holographic table. Dedicated holographic air floatation workbench is the best shock absorber. A simple shock absorption method can use sand boxes, microporous plastics, air cushions (inner tubes for cars and aircraft wheels) and cast iron or granite weighing 100-200kg, and an isolation cover should be installed. If you don't use a shield, do not ventilate the room when recording holograms, and do not speak loudly and away from the workbench. The method to check the stability of the workbench is to use a recording system component, arrange a long-arm Michelson interferometer system, adjust to only 3 to 5 interference fringes, and then watch the fringes, if there is vibration outside, and the interference fringes have not changed, it can be considered to be achieved Shock absorption. Put up one or two mirrors with a cushion. If the stripes do not change after a period of time, the shock absorption is considered good. In order to further determine whether the hologram is shock-absorbing, the position and direction of the mirror can be changed several times. If there is no change in the interference fringes, it can be determined that shock absorption is achieved. When the pulse laser is used as the recording light source, because the exposure time is extremely short, it is not necessary to provide measures for shock absorption and shock prevention. Optical element The optical elements such as lenses and mirrors produced by the holographic original work on the same principle as the general-purpose optical elements. 1. Lens In order to improve the light transmittance and prevent the hologram reproduction noise caused by unwanted reflection, the lens surface should be coated with antireflection coating. In addition, when choosing lenses, choose lenses that are free of defects and dirt, because they can cause noise during recording and reproduction of the hologram. 2. Reflector When the light is incident on the glass substrate of the ordinary reflector once, it must be refracted and then reflected, and the loss of reflected light is great. At the same time, both sides of the glass substrate will introduce stray light due to multiple reflections. Therefore, holographic plate-making requires high-reflectivity mirrors with high surface flatness and coated with multilayer reflective films. 3. Beam splitter The beam splitter is an important component of the recording system. Its function is to divide the laser beam into two or more beams, so as to serve as the reference wave and the illumination light wave of the object. The beam splitter is generally coated with an interference film on a long glass plate. There are two types of interference films: multilayer dielectric films and metal films. The split ratio can be changed continuously or in sections. A beam splitter made of polarizing elements can continuously adjust the beam splitting ratio, and in some cases it is necessary to split the beam into three or more beams. One method uses several beam splitters, and the other method uses multi-order diffraction of holographic gratings. The phase holographic grating can also be used as a beam splitter that continuously changes the split ratio. As long as the incident angle of the laser is changed, the split ratio can be continuously changed. 4. Beam expander Because the laser beam divergence angle is very small, a beam expander is needed to increase the beam divergence angle. Usually 20x, 40x microscope objectives, or a single positive or negative lens with a short focal length. Sometimes in order to reduce the optical components, convex spherical or concave spherical mirrors are used to simultaneously expand the beam and change the direction of the beam. Suppose that a positive lens with a focal length of f 'is used for beam expansion, and the spot diameter of the laser beam is 2, then the beam divergence angle after beam expansion is. Since the intensity distribution of the laser beam is Gaussian, the intensity distribution after the beam expansion is still Gaussian. In order to make the light intensity distribution uniform, a light bar is generally added in the light path. In this way, because only a small part of the light beam is used, a lot of energy is lost. 5. Pinhole filter The role of the pinhole filter is to limit the size of the beam and eliminate the high noise generated by the beam expander and the optical components that the beam passes before expanding the beam. The pinhole filter is generally a molybdenum sheet with a thickness of 25, which needs to be punched by laser to make a pinhole of 5 to 30 μm. The choice of pinhole size is related to the size of the speckle on the back focal plane of the beam expander and the size of the record. In the case of not considering the resolution of the image, the pinhole can be selected by referring to the above formula. Because the beam expander has a certain aberration, the actual light spot is larger than the value calculated by the above formula, and the pinhole size can be approximately calculated. The pinhole should be placed on the bright spot on the back focal plane of the beam expander when in use. Usually the pinhole and beam expander are mounted on a bracket, and the position of the pinhole can be adjusted in three perpendicular directions. First place the pinhole near the focal point of the beam expander and place a light screen behind the pinhole. First move the adjustment handwheel in the vertical (or horizontal) direction a little, and scan with the handwheel in the horizontal (or vertical) direction; if there is no light spot on the screen, continue to repeat it. After the light spot appears, follow the direction of the optical axis Or move the position of the pinhole in the vertical direction to gradually increase the brightness of the spot, and at the same time fine-tune the handwheel in the horizontal or vertical direction to observe the concentric bright and dark diffraction rings on the light screen; finally fine-tune along the optical axis to make the central bright spot The radius continues to expand and the brightness gradually increases until it is the brightest. 6. Diffusers Frosted glass, plaster, white paper, etc. can be used as diffusers. The diffuser is used to obtain a uniform scattered light field. First, the illuminance of the diffuser needs to be uniform to make the scattered light uniform. The difference between the luminous flux of a good diffuser in the direction and the luminous flux in the normal direction is very small, satisfying the relationship, so that the difference between and within the range of = ± 20 ° is less than 6%. 1. Preparation of the photographed object Most of the photographic objects commonly used in holography are objects with small size, high gloss and high reflectivity. For objects such as ornaments made of glass, apply a thin layer of grease to the surface before shooting to give it diffuse scattering properties. If a HeNe laser with an output power of 10mW is used, the size of the object to be illuminated can be up to 20cm × 30cm. If a model-selected argon ion laser is used, the object can be up to 30 x 50 cm. If you use a giant pulse ruby ​​laser, you can take portraits. 2. Choose the dry version The dry version on the market is marked with the laser that suits it. According to the customer's requirements for the type of holographic trademark and the color design requirements of the layout, choose a dry plate that is compatible with the wavelength and sensitivity of the recording light source. Choose the dry version with high resolution as much as possible at the right price. 3. Laser preparation and adjustment Although the laser beam has a high degree of coherence, it is necessary to check and adjust the laser before holographic plate making so that they can cooperate properly to achieve the ideal working state. There are five main items for laser inspection: ①Whether there is stray light in the case of single transverse mode; ② Whether the oscillation output power has reached the specified index; ③ Whether it is a single longitudinal mode, if it is a multi-longitudinal mode output, it is necessary to check which kind of multi-longitudinal mode; ④ Whether there is noise mixed in the oscillation output; ⑤ Whether it is stable continuous oscillation. Of the five inspections mentioned above, the first three are particularly important. Because it has a greater impact on the quality of the reproduced image of the hologram, it is important to check it. After inspection, if it is found that it does not meet the requirements, it will be adjusted. (1) Selection and adjustment of transverse mode Holography requires a light source with good spatial coherence, and the spatial coherence of the laser beam is determined by its transverse mode. The phase difference of the laser beam wavefront in the same transverse mode is fixed. As a laser for holographic recording, a single transverse mode is always selected. If the laser emits not a single transverse mode but a multi-transverse mode laser beam, uniform interference fringes cannot be formed on the hologram. When reproducing, horizontal mode graphics will appear, and spots will appear on the image. [next] There are three main reasons for multi-transverse mode: ①The design of the optical resonator is unreasonable; ② Attach dust to the reflector and Brewster window; ③ The parallelism of the resonant cavity is not good. The adjustment method is as follows: First, turn on the power to irradiate the laser light emitted by the laser on a piece of white paper, and observe whether it is a single transverse mode. If it is not a single transverse mode, analyze the cause. If it belongs to the case ①, for the external cavity helium-neon laser, you can replace it with a mirror whose curvature radius is compatible with the discharge tube. If you can't change it, you can finely adjust the parallelism of the mirror by observing the laser output pattern until you get a single transverse mode output, and then fix it, or put a needle with a diameter of about 2 ~ 3mm between the discharge tube and the mirror Hole, so that the laser beam hits the mirror through the pinhole to adjust. For the ruby ​​laser, a pinhole of 2 to 4 mm can be inserted between the ruby ​​rod and the reflector, and the position of the hole can be adjusted and fixed by observing the laser oscillation pattern. A thin metal plate can be used for the pinhole material. The size of the pinhole is determined by the diameter of the ruby ​​rod and the size of the oscillation, so its optimal value will be different. Various pinholes with different diameters should be prepared for use. If a complex pattern appears in the light spot, it is mostly because the dust is attached to the outside of the mirror at the output end of the laser. If it belongs to the case ②, you can use a blower to blow air on the mirror surface of the reflector and the windows of the Brewster window, or use compressed nitrogen to blow off the dust. If dust adheres to other dirt, you can use cotton balls or lens cleaning paper to dip acetone or a mixture of ethanol and ether (the ratio of ethanol and ether is 6: 4 or 5: 5). After shaking off the excess liquid, lightly Gently wipe the mirror surface, taking care not to scratch the mirror surface, and replace the mirror paper or cotton ball after rubbing once. In case ③, as in case ①, by observing the laser oscillation pattern, finely adjust the mirror of the resonant cavity so that the two mirrors are parallel. In the single transverse mode, the output power of the laser is the largest. If the two mirrors are still not parallel, you can use the following method to adjust their parallelism. ①Make small holes with a diameter of about 1 ~ 2mm with paper of appropriate thickness, and draw several concentric small holes with a pitch of about 1mm on it. ② Configure the discharge tube, ND filter, reflector, torch and pinhole as shown in Figure 5-9, turn on the power, and the discharge tube is in the discharge state. Put the pinhole at a position where the center of the discharge tube can be seen completely, and observe whether the concentric circle image drawn on the pinhole cardboard reflected on the reflector is clear. If you can't see clearly, you can use a flashlight to irradiate the pinhole cardboard, and then adjust the mirror to make the concentric image and the discharge tube concentric (ie coaxial), then the discharge tube is perpendicular to the reflector. By adjusting the other mirror in the same way, the parallelism of the resonant cavity can be adjusted. Note: Because the above method adjusts the parallelism of the resonant cavity by observing the reflector with the eye, when the reflector is adjusted to be parallel, a strong laser output will be produced to stab the eyes. Therefore, when approaching the required parallelism, remove your eyes and turn the adjusting screw of the reflecting mirror to adjust according to the expected moving direction of the reflecting mirror. For external cavity lasers, ND filters can be inserted between the Brewster window and the mirror or protective glasses can be used for adjustment. In the case of an internal cavity He-Ne laser, the discharge tube is deformed due to thermal expansion, and the transverse mode of the laser beam changes to reduce the output power. At this time, the installation state of the discharge tube can be adjusted slightly to reach its normal output power . Check if there is any light leakage other than the required laser output from the resonator, then use a thick black cloth to block the light. If the light leakage is bluish white, this is the light generated by the discharge of the discharge tube, and a small aperture light bar can also be set at the exit of the laser to eliminate it. (2) Longitudinal mode selection and adjustment For small He-Ne lasers as recording light, there is no need to specifically perform longitudinal mode selection. If large helium-neon lasers, argon ion lasers and ruby ​​lasers are used as recording light sources, especially when recording large scene objects requiring a long coherence length, the longitudinal mode must be selected and adjusted, and a single longitudinal mode laser beam must be used. (3) Noise reduction If: ①the discharge current of the laser is not appropriate; ② there is dust or air flow between the reflector and the Brewster window; ③ when multi-mode oscillation, a beat frequency is generated between the modes. Then, in the output power of the laser, noise that changes with time is mixed, and the coherence of the laser beam is deteriorated. The noise reduction method is: if the noise is caused by the first reason, for the He-Ne laser whose discharge current can be changed, the discharge current can be adjusted until the laser output while observing the laser output with an oscilloscope connected to the photogalvanometer. The power reaches the maximum and the noise is reduced to the minimum. For a HeNe laser with a fixed discharge current, a variable resistance voltage regulator can be installed at the primary end of the excitation current to adjust the discharge current. If it belongs to the second reason (only the external cavity or semi-external cavity lasers have this noise phenomenon), it can be solved by blocking the convection with the external air. If it is the third cause, it can be solved by single longitudinal mode selection method. In addition to the above three main reasons, if the excitation power supply is unstable, the excitation power supply voltage is not appropriate, the discharge tube and the reflector are not fixed, and the age of the laser has reached, it is also a cause of noise. Therefore, the cause of this type of noise should be carefully analyzed and solved using different methods. 4. Optical components and other components According to the type of holographic original recorded and the design requirements of the recording optical path, first draw a configuration diagram. Then choose the number of beam splitters, pinhole filters, convex lenses, total reflection mirrors, prepare a dry plate holder, a shutter of seconds or 1 / 250s, and a laser power meter that can measure several microwatts to ten microwatts. In addition, diffuser plates such as frosted glass plates are prepared. 5. Configure recording optical path (1) When the recording beam path is arranged parallel to the worktable surface, the beam direction should be parallel to the worktable. The height of the laser beam should be moderate. If the height of the laser output is not suitable, use the lifting (or lowering) light mirror to adjust to the appropriate height, and use the fine adjustment mechanism of the mirror or lifting mirror and a movable bracket with a fixed height mark to adjust the laser beam to The work surface is parallel.
Why
Choose Us:
1.
Experienced and Professional salon & beauty furniture manufacturer (15
years)
2.
Strict quality control, quality certificate available.
3.
Sufficient stock, timely shipment. Drop shipping available
4.
OEM/ODM available
5.
24 hours email reply pre and after sale service
6.
Good partner in USA, France, Australia to handle the shipment and after-sales
service.
Related Products:nail salon equipment,beauty salon furniture,hair salon equipment,salon Waiting Chair.
QUESTIONS
AND ANSWERS:
Q:
What forms of payment does CHAOHUI accept?
A:
We accept all major T/T, Western Union, Money Gram, Cash order.
30%
deposit prepaid, 70% balance rest paid before shipping and after Bill Of
Lading.
Q:
Why should I purchase salon furniture from CHAOHUI?
A:
Our factory is manufacturing of salon furniture for more than 15years, its
quality products have been sold to worldwide, so we may provide the best
equipment to fit your needs.
Q:
When will my order be shipped?
A:
On the average, 20 business days. It depends on the order quantities. Should it
take longer, we will make sure that you are aware of any delays.
Q:
What if I need warranty service?
A:
It`s easy, contact with us and our technical support staffs will handle
everything for you.
Q:If
the shipment is damaged ?
A:
CHECK
THE SHIPMENT UPON ARRIVAL!
Refuse
to accept the packages and it's necessary to ask claim from the insurance
company!
We
still offer free accessary free replace service during in 2 years!
Welcome to visit my factory!
Beauty Salon Equipment,Bed Cover,Foot Step,Nail Accessories ChaoHui Beauty Salon Equipment Co., Ltd. , https://www.chaohuibeauty.com
Preparation of Holographic Original Recording System
(2) Selection of beam splitting ratio After the beam parallelism is adjusted, a beam splitter must be installed. The selection of the beam splitter's beam splitting ratio should take into account the size of the recorded object and the surface scattering ability. The ratio of the intensity of the parametric and object beams at the surface of the recording medium is kept in the range of 1-10.
(3) The general formula of the degree of modulation of the interference fringes of the polarization direction of the laser beam is, where is the ratio of the parameter and the object beam, is the angle between the vibration directions of the parameter and the object beam, Ï„ (t) is the Time coherence. The above formula shows that polarized light perpendicular to each other cannot produce bright and dark stripes. Since the external cavity laser has a Brewster window, the laser output is polarized light, and the polarization direction should be perpendicular to the incident surface of the beam; although the internal cavity laser output laser beam is not polarized light, the light intensity in a certain vibration direction is the maximum Characteristics, so this direction should be perpendicular to the incident surface.
(4) The laser beam should be adjusted through the adjustment of the center of the beam expander and collimator lens. When the beam expander is installed, the beam expander should be adjusted up, down, left, or right (without pinhole) so that the center of the emitted spot coincides with the laser beam. ; When using a collimating lens, the position of the center of the lens should coincide with the center of the laser beam before the laser beam is expanded. The method is to observe whether a series of light spots reflected on both surfaces of the lens are on the same line.
(5) The mechanical structure of various components is stable. The brackets for installing various optical components have 2 to 4 degrees of freedom. During use, it is necessary to check whether there are any loose parts in each part of the mechanism. The fixing screws should be tightened. The adjustment part is better to be installed in the middle position. The bracket generally adopts a magnetic table base, and it should be firmly fixed to the table when recording.