High imaging resolution optical glass blanks for medium-free holographic imaging elements

Abstract

The application discloses a high imaging resolution optical glass blank for a medium-free holographic imaging element, and particularly relates to the field of optical glass blanks, and comprises the following components in mass fraction: 100-125 parts of silicon dioxide, 12-25 parts of boron oxide, 10-18 parts of sodium oxide, 5-12 parts of aluminum oxide, 6-15 parts of strontium oxide, 2-6 parts of magnesium oxide, 1-4 parts of calcium oxide, 0.8-2.5 parts of cerium oxide and 0.2-1.0 parts of praseodymium oxide. The rare earth ion doping structure formed by the cerium oxide and the praseodymium oxide is embedded in the silicon-oxygen-boron-oxygen network structure formed by the silicon dioxide and the boron oxide during the glass melting process, and a group of valence state trapping energy structures are formed. The free state ion migration inhibition network formed by the rare earth ion trapping energy structure and the limited skeleton mechanism is constructed, so that the nonlinear amplification problem that the pattern boundary is blurred and misread due to the high-frequency scattering induced by trace impurities in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical glass blanks, more particularly, the present application relates to high imaging resolution optical glass blanks for medium-free holographic imaging elements. BACKGROUND

[0002] In the current construction of medium-free holographic imaging elements, the optical glass blank assumes the basic carrier role of interference pattern propagation and phase control, and the material purity directly determines the image resolution and the recognition accuracy of the structure boundary;

[0003] In order to balance the cost and processing adaptability, the existing technology widely uses neutral or slightly alkaline silicate glass with sodium oxide-boron oxide-silicon dioxide as the basic system; however, this kind of glass formula has a serious underestimated technical hidden danger which is particularly fatal in high-precision imaging tasks: trace amounts of impurity ions such as trivalent iron, trivalent chromium and divalent nickel in the glass will form sub-nanometer oxide clusters due to thermal diffusion and local energy well effect during high-temperature annealing or laser processing of holographic patterns;

[0004] Although these clusters have weak influence on the transmittance in the visible light region and cannot be detected by the naked eye, they will exhibit high-frequency background scattering behavior in the wavelength range of four hundred to four hundred and seventy nanometers, especially in the blue and near-violet regions;

[0005] Such scattering is not a uniform fogging effect, but a very subtle but spatially unstable phase disturbance field, which often enhances and superimposes along the interference pattern boundary, resulting in blurred halos in the edge region of the holographic image, and the microstructure boundary is difficult to accurately decode; this phenomenon not only affects the edge sharpness of the pattern, but also causes local information redundancy or phase misplacement in three-dimensional reconstruction, ultimately causing misjudgment or interaction error of the recognition algorithm;

[0006] In actual engineering, this high-frequency scattering white fog phenomenon is often mistaken for laser system instability or recording algorithm error, as it presents weak randomness and is difficult to trace the root cause;

[0007] In summary, the existing technology of optical glass blanks with sodium oxide-boron oxide-silicon dioxide system as the core of the formula design has the following problems when facing high-resolution medium-free holographic imaging: the nonlinear light scattering amplification mechanism of trace impurities at the micro-optical scale is not inhibited, leading to systematic boundary blur and pattern misreading risk, which is difficult to avoid under the existing process optimization and traditional purification means, and constitutes a bottleneck restricting the holographic image analysis capability. SUMMARY

[0008] In order to overcome the above-mentioned defects of the prior art, embodiments of the present application provide a high imaging resolution optical glass blank for a medium-free holographic imaging element, and a free-state ion migration inhibition network is constructed by the combined action of a rare earth ion trapping energy structure and a limited framework mechanism to solve the nonlinear amplification problem of trace impurity induced high-frequency scattering leading to blurred pattern boundaries and misreading in the background art.

[0009] To achieve the above object, the present application provides the following technical solutions: a high imaging resolution optical glass blank for a medium-free holographic imaging element; the optical glass blank is composed of the following components in mass fraction: 100-125 parts of silicon dioxide, 12-25 parts of boron oxide, 10-18 parts of sodium oxide, 5-12 parts of aluminum oxide, 6-15 parts of strontium oxide, 2-6 parts of magnesium oxide, 1-4 parts of calcium oxide, 0.8-2.5 parts of cerium oxide, and 0.2-1.0 parts of praseodymium oxide.

[0010] The rare earth ion doping structure composed of the cerium oxide and the praseodymium oxide is embedded in the silicon-oxygen-boron-oxygen network structure composed of the silicon dioxide and the boron oxide during the glass melting process, forming a group of valence state trapping energy structures; the valence state trapping energy structures are used to bind the migration paths of free-state ions formed by trivalent iron, trivalent chromium, and divalent nickel, and position the free-state ions at stable node sites in the silicon-oxygen-boron-oxygen network structure.

[0011] In a preferred embodiment, the strontium oxide and the magnesium oxide cooperatively constitute a glass structure intermediate and induce the formation of a framework structure during thermal annealing, and the framework structure is used to construct a physical boundary that limits the migration path of free-state ions;

[0012] The sodium oxide and the aluminum oxide jointly regulate the concentration of non-bridge oxygen and the composition ratio of bridge oxygen connection structure in the glass network according to a set ratio, and construct a diffusion environment that limits the migration ability of alkali metal ions;

[0013] The glass blank outputs a uniform distribution area of the refractive index field in the imaging wavelength range of 380-470 nm under the synergistic action of the components, is used to limit the path superposition behavior of high-frequency stray signals, and constructs a phase consistency condition for the pattern boundary.

[0014] In a preferred embodiment, the mass fraction ratio of the cerium oxide to the praseodymium oxide is 3:1-4:1, the mass fraction ratio of the cerium oxide to the praseodymium oxide constructs a rare earth multi-valence trap structure, and the rare earth multi-valence trap structure is used to correspond to the excited state migration behavior of trivalent iron and trivalent chromium respectively, and form a double-trap coupling reaction site.

[0015] In a preferred embodiment, the strontium oxide and the magnesium oxide construct nanometer-scale crystalline domain non-continuous regions in a melt phase cooling process, the crystalline domain non-continuous regions form a confined diffusion network, and the continuous migration of divalent metal ions is blocked in a physical constraint manner.

[0016] In a preferred embodiment, the mass fraction ratio of the sodium oxide to the aluminum oxide is 2:1-2.5:1, and the proportional relationship of the mass fraction ratio of the sodium oxide to the aluminum oxide is used to regulate a bridge oxygen bond breaking threshold, construct a stable network region in which bridge oxygens and non-bridge oxygens coexist, and form a domain with a charge migration blocking effect.

[0017] In a preferred embodiment, 1-5 parts of zinc oxide are further included, and the zinc oxide and boron oxide jointly participate in forming a glass network structure in a melting stage, are used to regulate the uniformity of boron oxygen groups in the structure, and construct a chain structure region with a local charge density regulation capability in the glass matrix.

[0018] In a preferred embodiment, the cerium oxide exists in a form of a tetravalent ion valence state, and an atmosphere in a melting process is controlled to have an oxygen partial pressure of 0.1-0.25 standard atmospheres, and the atmosphere is used to inhibit rare earth ion valence state transfer behavior and construct a stable energy level trap structure under an oxidation-reduction balance.

[0019] In a preferred embodiment, an annealing process is implemented after the optical glass raw sheet is formed, the annealing temperature is controlled to be 490-520 degrees Celsius, the annealing duration is not less than 90 minutes, and a domain stress gradient in the annealing process is less than 1.2 megapascals, so as to realize the spatial uniformity of the refractive index in the raw sheet.

[0020] Technical effects and advantages of the present application:

[0021] By constructing a valence state trap energy structure formed by the cerium oxide and the praseodymium oxide embedded in a silicon-oxygen-boron-oxygen network structure, the free state ion migration path formed by the trivalent iron, the trivalent chromium and the divalent nickel is bound, and local phase field disturbance induced by the free state ion migration path in an imaging wave band is inhibited, so as to eliminate the blur halo phenomenon caused by high frequency scattering on a white light area pattern boundary, and realize the stable decoding capability of a high-resolution medium-free imaging system on a microstructure boundary.

[0022] A skeleton structure formed by the strontium oxide and the magnesium oxide is used to construct a stable confined network in an annealing process, and is used to construct a spatial physical boundary of a divalent ion migration path, so as to prevent the divalent ion migration path from forming a heterogeneous phase disturbance region due to a thermal diffusion process, and thus improve the optical purity and the refractive index uniformity of an imaging region.

[0023] The diffusion environment formed by sodium oxide and aluminum oxide in a mass ratio of 2:1-2.5:1 effectively controls the bridge oxygen bond breaking threshold, stabilizes the non-bridge oxygen-bridge oxygen coexistence region, structurally constructs migration obstacles to alkali metal free ions, and reduces the local refractive index deviation phenomenon caused by background charge disturbance;

[0024] The rare earth ion trap structure constructed based on the mass ratio of cerium oxide to praseodymium oxide corresponds to the excited state energy levels of trivalent iron and trivalent chromium, respectively, realizes multi-energy level locking configuration of the coupling reaction site, and improves the capture capacity of multivalent metal ions. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The process flowchart of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] With reference to the drawings in the description, Figure 1 the high imaging resolution optical glass wafer for the medium-free holographic imaging element of an embodiment of the present application;

[0028] The optical glass wafer is composed of the following components in mass ratio: 100-125 parts of silicon dioxide, 12-25 parts of boron oxide, 10-18 parts of sodium oxide, 5-12 parts of aluminum oxide, 6-15 parts of strontium oxide, 2-6 parts of magnesium oxide, 1-4 parts of calcium oxide, 0.8-2.5 parts of cerium oxide, and 0.2-1.0 parts of praseodymium oxide.

[0029] The rare earth ion doping structure composed of cerium oxide and praseodymium oxide is embedded in the silicon-oxygen-boron-oxygen network structure composed of silicon dioxide and boron oxide during the melting of the glass, forming a group of valence state trap energy structures; the valence state trap energy structure is used to bind the migration path of free state ions formed by trivalent iron, trivalent chromium, and divalent nickel, and position the free state ions at stable node sites in the silicon-oxygen-boron-oxygen network structure;

[0030] Among them, it is necessary to explain that the components of the optical glass wafer, silicon dioxide as a glass network former provides the main structure framework, boron oxide is introduced to form a boron-oxygen chain for adjusting the network structure flexibility and spectral response window, sodium oxide and aluminum oxide constitute the basic modification system for regulating the ratio of bridging oxygen and non-bridging oxygen structure in the glass network to control the migration ability of alkali metal ions, strontium oxide and magnesium oxide are used to construct the intermediate structure of glass and induce the formation of limited skeleton in the melting and annealing process to limit the diffusion path of impurity ions, calcium oxide is introduced as a stabilizer to regulate the melting viscosity and forming property, cerium oxide and praseodymium oxide are embedded into the network nodes as rare earth ion doping sources to form a trap energy structure for capturing impurity ions such as trivalent iron, trivalent chromium and divalent nickel to inhibit their induced high-frequency scattering behavior; This formula type is based on the construction of silicate system, with silicon dioxide as the main framework and appropriate boron component to enhance the network response regulation ability, and the mass fraction range of each modified component is determined according to its structural action limit to ensure that the glass forms an optical functional area with uniform refractive index, limited impurity migration and stable imaging boundary in the wavelength range of 380-470 nm.

[0031] Among them, cerium oxide and praseodymium oxide are high-valence rare earth ions that are doped into the silicon-oxygen-boron network structure constructed by silicon dioxide and boron oxide during glass melting, forming a trap energy structure with valence level capture function, which is used to bind the migration of impurity ions such as trivalent iron, trivalent chromium and divalent nickel and fix them at stable sites in the network structure, thereby establishing an ion migration shielding mechanism in the material system to suppress high-frequency scattering interference; In addition, in the formula selection, the combination of cerium and praseodymium can cover the excitation state energy level interval of multi-valence impurity ions, and the mass fraction is controlled between 0.8-2.5 parts and 0.2-1.0 parts to ensure the ion trapping density and spatial uniformity of the trap energy structure, while avoiding valence disturbance to the main network structure, ensuring that the glass has local energy level regulation function without introducing new migration channels.

[0032] In the glass structure intermediate composed of strontium oxide and magnesium oxide, a skeleton structure is induced to form during thermal annealing, which is used to construct a physical boundary to limit the migration path of free-state ions;

[0033] Said sodium oxide and aluminum oxide jointly regulate the concentration of non-bridging oxygen and the proportion of bridging oxygen connection structure in the glass network according to the set ratio to build a diffusion environment that limits the migration ability of alkali metal ions;

[0034] The glass wafer outputs a uniform distribution area of refractive index field in the imaging wavelength range of 380-470 nm under the synergistic action of each component, which is used to limit the path superposition behavior of high-frequency scattered signals and construct the phase consistency condition of pattern boundary;

[0035] The strontium oxide and the magnesium oxide cooperatively constitute a glass structure intermediate and induce the formation of a skeleton structure during thermal annealing, for constructing a physical boundary for limiting the migration path of free-state ions, while the sodium oxide and the aluminum oxide are in a set ratio to regulate the concentration of non-bridging oxygen and the proportion of bridging oxygen connection structure in the glass network, forming a limited environment for alkali ion migration and diffusion, so as to realize the uniform output of the refractive index field and suppress the path superposition of high-frequency stray signals under the synergistic action of the components, and establish the phase consistency condition of the pattern boundary in the imaging waveband; the system controls the nucleation density and annealing stress distribution of the skeleton structure by 6-15 parts of strontium oxide and 2-6 parts of magnesium oxide, and forms an adapted charge migration block region by 10-18 parts of sodium oxide and 5-12 parts of aluminum oxide, and ensures the maintenance of optical uniformity and spatial phase stability in the wavelength range of 380-470 nm through overall network structure adjustment.

[0036] The mass ratio of the cerium oxide to the praseodymium oxide is 3:1-4:1, and the mass ratio of the cerium oxide to the praseodymium oxide constructs a rare earth multi-valence trap structure, which is used to correspond to the excited state migration behavior of trivalent iron and trivalent chromium respectively, and form a double-trap coupling reaction site;

[0037] The mass ratio of the cerium oxide to the praseodymium oxide is controlled in the range of 3:1-4:1, and the formed rare earth multi-valence trap structure is used to correspond to the excited state migration behavior of trivalent iron and trivalent chromium in the glass network respectively, and construct a double-trap coupling reaction site through energy level docking relationship, so as to realize path recognition and energy level capture of multi-valence impurity ions, and suppress the migration accumulation behavior in the local area; the mass ratio is set based on the electron configuration of cerium and praseodymium and the redox stability interval, cerium in tetravalent state is mainly used to form a deep energy level trap with trivalent iron, and praseodymium in trivalent state is used to participate in the energy level coupling capture of trivalent chromium, and the ratio control covers different impurity transition paths without causing local charge imbalance, so as to maintain the phase stability and impurity shielding effect of the glass system during heat treatment and imaging.

[0038] The strontium oxide and the magnesium oxide construct a nanoscale crystalline domain discontinuous region in the melt phase cooling process, the crystalline domain discontinuous region forms a limited diffusion network, and the continuous migration of divalent metal ions is blocked by physical constraint;

[0039] It should be noted that the strontium oxide and magnesium oxide synergistically form a nanoscale crystalline domain non-continuous region during the melt phase cooling process, which constructs a limited diffusion network in the glass matrix to block the continuous migration path of divalent metal ions by physical space constraint, thereby cutting off the mechanism of impurities forming enrichment centers in a local range; the structure relies on 6-15 parts of strontium oxide to provide a rigid skeleton basis, and 2-6 parts of magnesium oxide to regulate the nucleation density and crystalline domain size, both of which are in a ratio that induces the formation of non-continuous crystalline phase boundaries during the cooling process, limits the ion diffusion scale and establishes a path interruption interface, so that the migrating ions cannot form stable channels in the spatial structure, reducing the probability of trajectory overlap and the risk of phase disturbance in the holographic imaging area.

[0040] The mass fraction ratio of sodium oxide to aluminum oxide is 2:1-2.5:1, and the proportional relationship of the mass fraction ratio of sodium oxide to aluminum oxide is used to regulate the bridge oxygen bond breaking threshold, to construct a stable network region coexisting with bridge oxygen and non-bridge oxygen, and to form a domain with charge migration retardation effect;

[0041] It should be noted that the mass fraction ratio of sodium oxide to aluminum oxide is controlled within the range of 2:1-2.5:1, and the proportional relationship is used to regulate the bridge oxygen bond breaking threshold in the glass network, to construct a structure region coexisting with bridge oxygen and non-bridge oxygen by adjusting the distribution state of aluminum oxide tetrahedron and alkali metal ions, and to form a domain with retardation effect on charge migration in the region; the proportion is set to provide 5-12 parts of aluminum oxide with positive network modification sites to enhance the bridge oxygen connection ability, and 10-18 parts of sodium oxide to provide non-bridge oxygen source to control the distribution uniformity of alkali metal ions and the probability of migration channel formation, thereby constructing a charge diffusion barrier structure with stable spatial configuration and low migration flux in the glass matrix, for inhibiting the interference of lateral drift of alkali metal ions and overall conductivity change on the phase consistency of holographic imaging.

[0042] It also includes 1-5 parts of zinc oxide, which participates in the formation of the glass network structure together with boron oxide during the melting stage, to regulate the distribution uniformity of boron oxygen groups in the structure and to construct a chain structure region in the glass matrix with local charge density regulation ability;

[0043] It should be noted that the zinc oxide is introduced into the glass system in a mass fraction of 1-5 parts, participates in the construction of the glass network structure together with boron oxide in the melting stage, is used for regulating the uniformity of the boron-oxygen group in the overall structure, forms a chain-shaped connecting unit with stable structure and difficult to be segregated in space, and establishes a structure segment with charge density regulation capacity in the local area, which is used for relieving the local phase disturbance caused by the charge concentration in the boron-oxygen network; the component setting is used for making the originally more active boron-oxygen group obtain higher distribution control in the three-dimensional structure through the participation of zinc ions in the charge compensation and structure filling of the boron-oxygen chain segment, so that the charge balance of the network is improved in the microscale, the dipole interference in the high-frequency response area is weakened, and the phase stability and resolution consistency of the imaging area are improved.

[0044] The cerium oxide exists in the form of tetravalent ion valence state, and the atmosphere in the melting process is: the oxygen partial pressure is controlled to be 0.1-0.25 standard atmosphere; the atmosphere is used for inhibiting the valence state transfer behavior of rare earth ions, and a stable energy level trap structure is constructed under the redox balance;

[0045] It should be noted that the cerium oxide exists in the form of tetravalent ion valence state in the glass melting process, the melting atmosphere is controlled in the range of 0.1-0.25 standard atmosphere by controlling the oxygen partial pressure, the rare earth ion system is maintained in the redox balance state, the valence state transition of cerium oxide is avoided under high temperature conditions, so that the trap energy state site corresponding to the energy level of trivalent iron ions is stably formed in the network structure; the atmosphere regulation strategy is based on the demand of tetravalent cerium for electron capture ability, and the oxygen partial pressure setting range is used for restraining the valence state transition threshold of cerium ions, avoiding the formation of trivalent cerium to cause the energy level shift or failure of the trap energy structure, so as to realize the valence state stability and energy level function continuity of the rare earth trap energy structure in the glass body, and provide necessary energy band matching conditions for subsequent impurity ion path capture.

[0046] The optical glass original piece is formed and then annealed, the annealing temperature is controlled to be 490-520 degrees Celsius, the annealing duration is not less than 90 minutes, and the stress gradient of the structure domain in the annealing process is less than 1.2 megapascals, so as to realize the spatial uniformity of the refractive index in the original piece;

[0047] The optical glass blank is annealed after forming, the annealing temperature is set to 490-520 degrees Celsius, the duration is not less than 90 minutes, the stress gradient of the structure domain during the annealing process is controlled to be less than 1.2 MPa, which is used to release the structural residual stress accumulated in the glass during the melting and cooling stages, and to ensure that the refractive index field is uniformly distributed in the spatial scale; the above parameter settings are determined according to the softening temperature range of the skeleton domain of the glass intermediate structure composed of strontium oxide, magnesium oxide and aluminum oxide, 490 degrees Celsius is the starting temperature of the glass network relaxation, and 520 degrees Celsius is close to the upper limit of the oxygen connection release in the amorphous structure, which ensures that the stress release process is sufficient but does not cause phase structure rearrangement, and the annealing time of more than 90 minutes cooperates with the stress gradient limit of less than 1.2 MPa to establish a distortion-free optical domain in the glass body, preventing local stress-induced refractive index drift and optical distortion in subsequent holographic imaging.

[0048] Table 1: Relationship table of rare earth doping ratio and iron ion migration residual

[0049]

[0050] Table 2: Annealing parameter and refractive index uniformity response table

[0051]

[0052] It should be noted that for the rare earth doping ratio and iron ion migration residual relationship table in Table 1, the mass fraction ratio of cerium oxide to praseodymium oxide is set as the main variable, and four groups of doping conditions (A-D samples) are set respectively to verify the capture effect of the trap energy structure formed by the rare earth ions in the silicon-oxygen-boron oxide network structure on the migration behavior of trivalent iron ions; wherein, the rare earth mass ratio is set based on Ce 4+ Deep trap construction ability of iron ions and Pr 3+ Synergistic effect on shallow energy level coupling, the proportion range covers the 3:1-4:1 doping window proposed in this scheme, which are samples A (2:0.6, 3.3:1), B (1.8:0.5, 3.6:1), C (1.5:0.4, 3.75:1) and D (0.8:0.2, 4:1);

[0053] Each group of samples controls the oxygen partial pressure to be 0.1-0.25 standard atmosphere during melting to ensure that cerium oxide exists in the form of tetravalent state, forming a valence state trap energy structure; the transverse migration behavior of iron ions under thermal load is quantitatively analyzed by laser-induced diffusion test method after the glass blank is melted, the sampling window is 50 microns below the glass surface, and the scanning area is 1cm 2 The accumulated concentration of iron ions in the migrated area is detected by plasma emission mass spectrometry, and the iron ion migration residual density is calculated by integrating the migration depth, in ng / cm 2For units;

[0054] The sample A has the highest doping amount of cerium oxide (2 parts), but the proportion of Pr is low, and the trap energy structure captures Ce 4+ The deep traps are formed under the dominance of the window of the matching valence state, and part of the iron ions escapes due to the insufficient window, resulting in a residual value of 4.48 ng / cm 2 ; The sample C is the best combination (1.5:0.4, 3.75:1), and the double-trap coupling structure is formed under the synergistic effect of Ce / Pr energy levels, the capture window is the largest, and the migration residual is only 2.57 ng / cm 2 ; The sample D has the lowest doping amount, the trap density is insufficient, only the boundary state trap is formed, the migration control fails, and the residual rises to 5.70 ng / cm 2 , which verifies the necessity of the upper and lower limits of the doping ratio and the number of parts.

[0055] Based on the annealing parameters and refractive index uniformity response table in Table 2, the annealing temperature and time are set as the main control variables, and the detection results of the stress release state and the refractive index spatial distribution of the optical glass original piece under different annealing conditions are used to verify the support relationship between the limited skeleton structure and the stress control window for the formation of imaging phase stability. The four groups of samples (A-D) are prepared based on the same formula system, and the difference is only in the annealing parameter setting: sample A is set to 490°C for 90 minutes, sample B and C are set to 500°C and 510°C respectively, and the time is 100 minutes, and sample D is set to 520°C for 90 minutes.

[0056] After the glass original piece is formed, it is immediately annealed, and the release process of the residual stress in the glass internal structure domain caused by rapid cooling is controlled by setting the holding temperature and time; the stress gradient is obtained by polarized light interference method combined with stress birefringence test, the glass cross section is selected along the thickness direction, the photoelastic image is recorded and the maximum principal stress change range is calculated, and the structure stress gradient is output in units of megapascal; -4

[0057] The experimental results show that samples B and C (annealed at 500°C and 510°C respectively, and the holding time is 100 minutes) show the lowest stress gradient (0.84 / 0.83 MPa) and smaller refractive index deviation (1.34×10 -4 and 1.25×10 -4 ), which verifies that the phase field tends to be uniform after the limited skeleton structure releases the network stress in the middle temperature zone; sample A, although it meets the lower limit (490°C, 90 minutes), the stress release is not complete, resulting in a gradient of 1.11 MPa, and the refractive index fluctuation remains at 1.34×10​-4 ; sample D, though stress was released sufficiently (0.83 MPa), but due to the annealing temperature was close to the upper limit of the skeleton conversion temperature zone of the silicon-oxygen-boron-oxygen network (520℃), leading to local structure deconstruction and recombination, causing refractive index field rearrangement, its maximum deviation rose to 1.98×10 -4 , indicating that although the stress is the smallest at high temperature, it cannot guarantee optical uniformity, which proves that the upper limit boundary setting of the annealing temperature window (490-520℃) proposed in this scheme has basis;

[0058] In summary, the experimental parameters and measurement results listed in Table 2 truly reflect the internal logic between the skeleton structure, stress release mechanism and optical response proposed in this scheme, especially proving that the technical settings of annealing time ≥ 90 minutes, stress gradient ≤ 1.2 MPa and temperature not exceeding 520℃ have stability and necessity.

[0059] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-resolution optical glass substrate for use in dielectric-free holographic imaging elements, characterized in that: The optical glass substrate is composed of the following components in parts by weight: 100-125 parts silicon dioxide, 12-25 parts boron oxide, 10-18 parts sodium oxide, 5-12 parts aluminum oxide, 6-15 parts strontium oxide, 2-6 parts magnesium oxide, 1-4 parts calcium oxide, 0.8-2.5 parts cerium oxide, and 0.2-1.0 parts praseodymium oxide; The rare earth ion doped structure composed of cerium oxide and praseodymium oxide is embedded in the silicon-oxygen-boron-oxygen network structure jointly constructed by silicon dioxide and boron oxide during the glass melting process, forming a set of valence state trapping structures. The valence state trapping structures are used to bind the migration paths of free ions formed by trivalent iron, trivalent chromium, and divalent nickel, and to locate the free ions at the node sites in the silicon-oxygen-boron-oxygen network structure.

2. The high-resolution optical glass substrate for a medium-free holographic imaging element according to claim 1, characterized in that: The strontium oxide and magnesium oxide synergistically form a glass structure intermediate and induce the formation of a framework structure during the thermal annealing process; The sodium oxide and aluminum oxide are mixed in a set ratio to control the concentration of non-bridging oxygen and the composition ratio of bridging oxygen connection structure in the glass network, thereby creating a diffusion environment that restricts the migration ability of alkali metal ions. Under the synergistic effect of its components, the glass substrate outputs a distribution area of ​​refractive index field within the imaging wavelength range of 380-470 nanometers.

3. The high-resolution optical glass substrate for a medium-free holographic imaging element according to claim 2, characterized in that: The mass ratio of cerium oxide to praseodymium oxide is 3:1-4:

1. This mass ratio of cerium oxide to praseodymium oxide constructs a rare earth multivalent trap structure. This rare earth multivalent trap structure forms coupling reaction sites for trivalent iron and trivalent chromium, inhibiting the excited-state migration behavior of trivalent iron and trivalent chromium.

4. The high-resolution optical glass substrate for a medium-free holographic imaging element according to claim 3, characterized in that: During the cooling process of the molten phase, strontium oxide and magnesium oxide construct nanoscale discontinuous crystal domains. These discontinuous crystal domains form a confined diffusion network, which blocks the continuous migration of divalent metal ions through physical constraints.

5. The high-resolution optical glass substrate for a medium-free holographic imaging element according to claim 4, characterized in that: The mass ratio of sodium oxide to aluminum oxide is 2:1 to 2.5:

1. This ratio is used to regulate the bridging bond breaking threshold, construct a stable network region where bridging and non-bridging oxygen coexist, and form a structural domain with charge migration hindrance effect.

6. The high-resolution optical glass substrate for a medium-free holographic imaging element according to claim 5, characterized in that: It also includes 1-5 parts of zinc oxide, which together with boron oxide participate in the formation of the glass network structure during the melting stage.

7. The high-resolution optical glass substrate for a medium-free holographic imaging element according to claim 6, characterized in that: The cerium oxide exists in the form of tetravalent ions, and the atmosphere during the melting process is: the oxygen partial pressure is controlled at 0.1-0.25 standard atmospheres; the atmosphere is used to suppress the valence transfer behavior of rare earth ions.

8. The high-resolution optical glass substrate for a medium-free holographic imaging element according to claim 7, characterized in that: After the optical glass substrate is formed, it undergoes an annealing process. The annealing temperature is controlled at 490-520 degrees Celsius, the annealing duration is not less than 90 minutes, and the stress gradient of the structural domain is less than 1.2 MPa during the annealing process.

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