Imaging system including a beam guide element with high solarization resistance in the blue spectral region

Abstract

The present invention relates to an imaging system including at least one laser light source having a wavelength in the blue spectral region and a beam guiding element having high solarization resistance at high power densities. The present invention also relates to the use of the imaging system, particularly in projectors and material processing.

Description

[Technical Field]

[0001] The present invention relates to an imaging system including at least one laser light source having a wavelength in the blue spectral region and a beam guiding element having high solarization resistance at high beam power densities. The present invention also relates to the use of the imaging system, particularly in projectors and material processing. [Background technology]

[0002] Currently, projector light sources are constantly increasing in luminous flux and power density, moving from xenon to laser phosphors and to pure RGB laser light sources. Today's cinema projectors with laser light sources have luminous fluxes of up to 75,000 lumens and powers of up to 50 W / cm. 2 Surface power densities of up to 1000 times higher have been achieved. As the luminous flux and power density increase, the thermal load on the optical components increases, which impairs the quality and long-term stability of the projection. The optical system of a cinema projector typically consists of a large-volume prism device and a projection objective. The prism device in particular is exposed to high thermal loads. This places increasing demands on optical glass in terms of low absorption losses, i.e., maximum transmittance, and low tendency to solarization, i.e., low induced absorption losses during use.

[0003] Traditional xenon-based cinema projectors have a maximum luminous flux of up to 45,000 lumens, but current laser-based projectors offer a luminous flux of up to 75,000 lumens and a power output of 50 W / cm². 2 A surface power density of up to 10 ...

[0004] Projection systems often consist of complex prism assemblies that guide the individual color channels to the DLP chip and then mix the signals to generate the image. The optical path length can be 100 mm to over 200 mm. The respective light absorption within the prism assembly creates temperature gradients and thermal lensing effects. Therefore, the prism glass should have as high a transmittance as possible in the visible wavelength range. Another effect, which becomes increasingly significant as the projector's luminous flux increases, is the solarization effect in the glass. The absorption-induced creation of defect centers in the prism glass can lead to a decrease in transmittance, which in turn creates further thermal lensing effects.

[0005] However, such solarization effects are not only relevant to the optical systems of current projectors: they are also becoming increasingly important in the context of materials processing applications. Summary of the Invention [Problem to be solved by the invention]

[0006] It is therefore an object of the present invention to provide an imaging system with a beam guide element that has high solarization resistance in the blue spectral region and is therefore not only outstanding for use in projectors but can also be used in material processing applications. [Means for solving the problem]

[0007] An imaging system is particularly a system comprising at least one light source and at least one beam guiding element, in particular a lens, prism, aspheric surface, parallel plate, freeform, fast-axis collimator, and / or light guide rod. The light guide rod here utilizes total internal reflection at a glass-air boundary and typically has a length not exceeding 300 mm. Such imaging systems are used, for example, in projectors, in particular cinema projectors. In this context, the imaging system guides light from the light source in a targeted manner to generate an image, for example on a screen, that can be perceived by an observer. The highest power densities usually occur in prisms, especially prisms that perform color channel mixing. Therefore, it is particularly important that such prismatic beam guiding elements are made of materials that can withstand such power densities without significant solarization effects. Imaging systems are also used in material processing. By targeted beam guiding, for example by a fast-axis collimator, the light from the light source can be focused on the material to be processed so that the energy input of the optical radiation is available for material processing.

[0008] The problem is solved by the subject matter of the claims. In particular, the problem is solved by an imaging system, comprising: a) Wavelength λ in the spectral range of 380 nm to 490 nm B at least one laser source B having b) Beam guide elements Equipped with The laser source B has an output of 10 W / cm at at least one point of the beam guiding element. 2 and the beam guiding element is made of glass having a quality factor F(436 nm)=S(436 nm)×(Ext0(436 nm)+Ext1(436 nm)) / k, where F(436 nm)<15 ppm / W. This is solved by the imaging system.

[0009] Another object is to provide an imaging system, comprising: a) Wavelength λ in the spectral range of 380 nm to 490 nm B at least one laser source B having a wavelength λ in the spectral range from above 490 nm to 585 nm; G at least one laser light source G having a wavelength λ in the spectral range from above 585 nm to 750 nm; R at least one laser source R having b) Beam guide elements Equipped with Laser source B, laser source G and laser source R have an output of 10 W / cm at at least one point of the beam guiding element. 2 and the beam guiding element is suitable for generating an average surface power density of greater than 40 ppm / W, the beam guiding element having a quality factor F(RGB)=F(436 nm)+F(546 nm)+F(644 nm)=S(436 nm)×(Ext0(436 nm)+Ext1(436 nm)) / k+S(546 nm)×(Ext0(546 nm)+Ext1(546 nm)) / k+S(644 nm)×(Ext0(644 nm)+Ext1(644 nm)) / k and consisting of glass with F(RGB)<40 ppm / W. This can also be solved by the imaging system.

[0010] Another object is to provide an imaging system, comprising: a) Wavelength λ in the spectral range of 380 nm to 490 nm B at least one laser source B having b) Beam guide elements Equipped with The laser source B has an output of 10 W / cm at at least one point of the beam guiding element. 2 the beam guide element is suitable for generating an average surface power density of greater than 1000 W, and the beam guide element has an induced absorbance Ext1 (436 nm) of glass with Ext1 (436 nm) <0.01 / cm; This can also be solved by the imaging system.

[0011] Another object is to provide an imaging system, comprising: a) Wavelength λ in the spectral range of 380 nm to 490 nmB at least one laser source B having a wavelength λ in the spectral range from above 490 nm to 585 nm; G at least one laser light source G having a wavelength λ in the spectral range from above 585 nm to 750 nm; R at least one laser source R having b) Beam guide elements Equipped with Laser source B, laser source G and laser source R have an output of 10 W / cm at at least one point of the beam guiding element. 2 the beam guide element is suitable for generating an average surface power density of greater than 1000 nm, and the beam guide element has an induced absorbance Ext1(RGB)=Ext1(436 nm)+Ext1(546 nm)+Ext1(644 nm), and is made of glass with Ext1(RGB)<0.03 / cm, This can also be solved by the imaging system.

[0012] Another object is to provide an imaging system, comprising: a) Wavelength λ in the spectral range of 380 nm to 490 nm B at least one laser source B having b) Beam guide elements Equipped with The laser source B has an output of 10 W / cm at at least one point of the beam guiding element. 2 and the beam guiding element is suitable for generating an average surface power density of greater than 1000 .ANG., and has the following properties: Quality factor F(436nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k, where F(436nm) < 15 ppm / W, Induced absorbance Ext1 (436 nm) < 0.01 / cm, The glass comprises one or more of: This can also be solved by the imaging system.

[0013] Another object is to provide an imaging system, comprising: a) Wavelength λ in the spectral range of 380 nm to 490 nmB at least one laser source B having a wavelength λ in the spectral range from above 490 nm to 585 nm; G at least one laser light source G having a wavelength λ in the spectral range from above 585 nm to 750 nm; R at least one laser source R having b) Beam guide elements Equipped with Laser source B, laser source G and laser source R have an output of 10 W / cm at at least one point of the beam guiding element. 2 and the beam guiding element is suitable for generating an average surface power density of greater than 1000 .ANG., and has the following properties: Quality factor F(436nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k, where F(436nm) < 15 ppm / W, Quality factor F(RGB) = F(436nm) + F(546nm) + F(644nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k + S(546nm) × (Ext0(546nm) + Ext1(546nm)) / k + S(644nm) × (Ext0(644nm) + Ext1(644nm)) / k, where F(RGB)<40ppm / W, Induced absorbance Ext1 (436 nm) < 0.01 / cm, Induced absorbance Ext1(RGB) = Ext1(436nm) + Ext1(546nm) + Ext1(644nm), where Ext1(RGB)<0.03 / cm; The glass may have one or more of these properties, for example, at least two or at least three of these properties. This can also be solved by the imaging system.

[0014] Another object is to provide an imaging system, comprising: a) Wavelength λ in the spectral range of 380 nm to 490 nm B at least one laser source B having a wavelength λ in the spectral range from above 490 nm to 585 nm; Gat least one laser light source G having a wavelength λ in the spectral range from above 585 nm to 750 nm; R at least one laser source R having b) Beam guide elements Equipped with Laser source B, laser source G and laser source R have an output of 10 W / cm at at least one point of the beam guiding element. 2 and the beam guiding element is suitable for generating an average surface power density of greater than 1000 .ANG., and has the following properties: Quality factor F(436nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k, where F(436nm) < 15 ppm / W, Quality factor F(RGB) = F(436nm) + F(546nm) + F(644nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k + S(546nm) × (Ext0(546nm) + Ext1(546nm)) / k + S(644nm) × (Ext0(644nm) + Ext1(644nm)) / k, where F(RGB)<40ppm / W, Induced absorbance Ext1 (436 nm) < 0.01 / cm, The glass may have one or more of the following properties, for example, at least two of these properties: This is solved by the imaging system.

[0015] The imaging system of the present invention may include further components, such as an image generating chip (particularly a DLP chip) and / or projection optics.

[0016] The imaging system of the present invention uses wavelength λ in the spectral range of 380 nm to 490 nm. B Preferably, the imaging system includes a laser light source B having a wavelength λ in the spectral range of 400 nm to 485 nm, more preferably 420 nm to 480 nm, more preferably 430 nm to 475 nm, more preferably 440 nm to 470 nm, more preferably 445 nm to 460 nm. B The laser light source B has:

[0017] The imaging system of the present invention may optionally include a separate laser light source.

[0018] The imaging system of the present invention captures signals at wavelengths λ in the spectral range from greater than 490 nm to 585 nm. G Preferably, the imaging system includes a laser light source G having a wavelength λ in the spectral range of 510 nm to 580 nm, more preferably 520 nm to 570 nm, more preferably 530 nm to 560 nm, more preferably 540 nm to 550 nm. G The laser light source G has:

[0019] The imaging system of the present invention captures signals at wavelengths λ in the spectral range from greater than 585 nm to 750 nm. R Preferably, the imaging system includes a laser light source R having a wavelength λ in the spectral range of 600 nm to 720 nm, more preferably 610 nm to 700 nm, more preferably 620 nm to 680 nm, more preferably 630 nm to 660 nm, more preferably 640 nm to 650 nm. R The laser light source R has:

[0020] Very particularly preferably, the imaging system of the invention is configured to emit light at wavelengths λ in the spectral range from 380 nm to 490 nm. B In addition to the laser light source B having a wavelength λ in the spectral range from 490 nm to 585 nm, G and a laser light source G having a wavelength λ in the spectral range from greater than 585 nm to 750 nm. R and a laser light source R having

[0021] Wavelength λ in the spectral range of 380nm to 490nm B at least one point of the beam-guiding element, preferably at least 0.1 cm from the beam-guiding element. 2 , more preferably at least 0.5 cm 2 , more preferably at least 1 cm 2 , more preferably at least 2 cm2 , more preferably at least 3 cm 2 , more preferably at least 5 cm 2 , more preferably at least 7 cm 2 , more preferably at least 9 cm 2 On a flat surface, 10W / cm 2 Preferably, the wavelength λ is in the spectral range of 380 nm to 490 nm. B at least one point of the beam-guiding element, preferably at least 0.1 cm from the beam-guiding element. 2 , more preferably at least 0.5 cm 2 , more preferably at least 1 cm 2 , more preferably at least 2 cm 2 , more preferably at least 3 cm 2 , more preferably at least 5 cm 2 , more preferably at least 7 cm 2 , more preferably at least 9 cm 2 On a flat surface, 10W / cm 2 Over 400W / cm 2 up to 20 W / cm 2 ~300W / cm 2 , more preferably 50 W / cm 2 ~250W / cm 2 , e.g., 75 W / cm 2 ~200W / cm 2 or 100W / cm 2 ~150W / cm 2 is suitable for generating an average surface power density of

[0022] The imaging system of the present invention preferably includes a beam guiding element made of glass having a quality factor F(436 nm)=S(436 nm)×(Ext0(436 nm)+Ext1(436 nm)) / k, with F(436 nm)<15 ppm / W.

[0023] When defects are induced in a material by irradiation with energetic photons in the UV region, changes in spectral transmittance occur. If the defects are located in the visible spectral region, this causes undesirable color shifts. This phenomenon is particularly undesirable for glass optical components. Surprisingly, it has now been shown that high laser power densities can induce defect centers in the visible spectral region, e.g., at 455 nm (solarization), a type of defect that occurs only when conventional light sources emit in the UV / NUV. Without being limited to a specific explanation, the occurrence of the solarization effect upon visible light irradiation is primarily attributed to nonlinear effects that arise with high power densities. With excitation at sufficient power densities, two-photon absorption can occur, which corresponds to photon energy at half the wavelength (e.g., 455 nm / 2 = 227.5 nm), i.e., UV absorption. In contrast to conventional UV solarization, this effect is generally not limited to the volume near the surface of the glass facing the light source, but can occur along the entire optical path length. The defect centers formed induce new absorption bands, which reduces the transmitted intensity.

[0024] The induced absorption bands cause temperature increases in the optical material / glass, as the refractive index and geometric path change with temperature, causing wavefront retardation and undesirable imaging errors.

[0025] From here, 10 W / cm at at least one point on the beam guiding element 2 Particularly high demands are placed on the materials of the beam guide elements used in imaging systems comprising laser light sources suitable for generating an average surface power density of greater than 1000 .It is therefore an object of the present invention to provide an imaging system in which undesired imaging errors are prevented or at least significantly reduced.

[0026] An exemplary embodiment of the imaging system of the present invention is shown schematically in Figure 1. According to this embodiment, the imaging system is a DLP projector. The expression "DLP" is an abbreviation for the term "Digital Light Processing". The imaging system of the present invention shown in Figure 1 comprises a laser light source 1 and a beam guiding element 2. According to the present invention, the imaging system emits light at wavelengths λ in the spectral range of 380 nm to 490 nm. B The imaging system of the present invention may include at least one laser light source B having a wavelength of 1000 nm or more, and in particular, a green laser light source and / or a red laser light source in addition to a blue laser light source. Laser light source 1, which is depicted as a single box in FIG. 1 for simplicity, may be, for example, three different colored diode lasers, in particular, a blue diode laser, a green diode laser, and a red diode laser. Alternatively, only a blue laser light source may be provided. In some embodiments, the blue light emitted from the blue laser light source can be converted by a converter, in particular a ceramic converter, via luminescence emission into light having a longer wavelength, for example, yellow light, green light, red light, and / or yellow-green light.

[0027] In the DLP projector shown in FIG. 1 , the laser light source 1 emits blue, green, and red light (represented by arrows 5). This can be achieved, for example, by having the laser light source 1 represent blue, green, and red diode lasers. Alternatively, only a blue laser can be provided, with additionally emitted green and red light generated using a converter material. After leaving the laser light source 1, the three colors 5 emitted from the laser light source 1 reach the beam guide element 2. The beam guide element 2 can be a prism device including at least one prism, for example, multiple prisms. The prism device can be composed of, for example, two or three prisms. Arrows 6 indicate that the beam guide element 2 deflects the three colors of light emitted from the laser light source 1 toward the image generation chip 3. Preferably, each of the three colors (blue, green, and red) is deflected toward its respective image generation chip 3. For simplicity, only one box representing the image generation chip 3 is shown in FIG. 1 . A preferred image generation chip 3 is a DLP chip 3. Preferably, the imaging system includes one image generating chip 3 for each color channel, and therefore the box shown in Figure 1 preferably represents three image generating chips 3 (one for blue, one for green and one for red), in particular three DLP chips 3.

[0028] The images produced by the DLP chip 3 (in particular the blue, green and red images respectively) then reach the beam guiding element 2, in particular the prism 2 or prism arrangement 2. This is indicated by the arrow 7.

[0029] The beam guiding element 2 then passes the color composite image to the projection optics 4. This is indicated by the arrow 8.

[0030] In particular, the surface power density can be very high in the region of the beam guiding element 2. It is therefore important that the beam guiding element 2 consists of glass with a quality factor according to the invention.

[0031] The problem is solved in particular in that the beam guide element consists of glass with a quality factor F(436 nm)=S(436 nm)×(Ext0(436 nm)+Ext1(436 nm)) / k, where F(436 nm)<15 ppm / W.

[0032] The quality factor F takes into account various factors that, in the combinations found herein, lead to a reduction in imaging errors. The factors considered include both wavelength-dependent and wavelength-independent factors. The quality factor F(436nm) at a wavelength of 436nm describes the behavior of the glass in the spectral region from 380nm to 490nm, which also describes the behavior of the glass throughout the visible spectral region. Preferably, F(436nm)<15ppm / W.

[0033] The behavior of glass at wavelengths outside the 380-490 nm range can also contribute to image errors, albeit to a lesser extent in some cases. The quality factor F(436 nm) is generally sufficient to describe the quality of glass. However, in certain cases, it may be useful to consider not only the behavior of glass at 436 nm, but also its behavior at 546 nm, as representative of the wavelength range from above 490 nm to 585 nm, and / or its behavior at 644 nm, as representative of the wavelength range from above 585 nm to 750 nm. Preferably, the beam guiding element consists of glass having a quality factor F(546 nm) = S(546 nm) x (Ext0(546 nm) + Ext1(546 nm)) / k, where F(546 nm) < 12 ppm / W, and / or glass having a quality factor F(644 nm) = S(644 nm) x (Ext0(644 nm) + Ext1(644 nm)) / k, where F(644 nm) < 10 ppm / W.

[0034] From the behavior of the glass at 436 nm, 546 nm and 644 nm, the quality factor F(RGB) can be determined. Preferably, the beam guiding element consists of glass with a quality factor F(RGB) = F(436 nm) + F(546 nm) + F(644 nm) = S(436 nm) × (Ext0(436 nm) + Ext1(436 nm)) / k + S(546 nm) × (Ext0(546 nm) + Ext1(546 nm)) / k + S(644 nm) × (Ext0(644 nm) + Ext1(644 nm)) / k and with F(RGB)<40 ppm / W.

[0035] The quality factor F takes into account the degree of heating S(λ), the uninduced absorbance Ext0(λ), the induced absorbance Ext1(λ) and the thermal conductivity k of the glass. The degree of heating, the uninduced absorbance and the induced absorbance are wavelength-dependent quantities. Thermal conductivity is wavelength-independent. The uninduced absorbance Ext0(λ) can be used as a measure of the absorbance in the as-delivered state or before intended use. The induced absorbance Ext1(λ) can be used as a measure of the absorbance potentially induced by appropriate manipulation.

[0036] Preferably, F(436 nm)<15 ppm / W. More preferably, F(436 nm) is at most 14.5 ppm / W, more preferably at most 14 ppm / W, more preferably at most 13.5 ppm / W, more preferably at most 13 ppm / W, more preferably at most 12.5 ppm / W, more preferably at most 12 ppm / W, more preferably at most 11.5 ppm / W, more preferably at most 11 ppm / W, more preferably at most 10.5 ppm / W, more preferably at most 10 ppm / W, more preferably at most 9.5 ppm / W, more preferably at most 9 ppm / W, more preferably at most 8.5 ppm / W, more preferably at most 8 ppm / W, more preferably at most 7.5 ppm / W, more preferably at most 7 ppm / W, more preferably at most 6.5 ppm / W, more preferably at most 6 ppm / W, more preferably at most 5.5 ppm / W, more preferably at most 5 ppm / W, more preferably at most 4.5 ppm / W, more preferably at most 4 ppm / W, more preferably at most 3.5 ppm / W, more preferably at most 3 ppm / W. In some embodiments, F(436 nm) is at least 0.1 ppm / W, at least 0.5 ppm / W, at least 1 ppm / W, or at least 2 ppm / W.

[0037] Preferably, F(546nm)<12 ppm / W. More preferably, F(546nm) is at most 11.5 ppm / W, more preferably at most 11 ppm / W, more preferably at most 10.5 ppm / W, more preferably at most 10 ppm / W, more preferably at most 9.5 ppm / W, more preferably at most 9 ppm / W, more preferably at most 8.5 ppm / W, more preferably at most 8 ppm / W, more preferably at most 7.5 ppm / W, more preferably at most 7 ppm / W, more preferably at most 6.5 ppm / W, more preferably at most 6 ppm / W, more preferably at most 5.5 ppm / W, more preferably at most 5 ppm / W, more preferably at most 4.5 ppm / W, more preferably at most 4 ppm / W, more preferably at most 3.5 ppm / W, more preferably at most 3 ppm / W, more preferably at most 2.5 ppm / W, more preferably at most 2 ppm / W. In some embodiments, F(546 nm) is at least 0.001 ppm / W, at least 0.005 ppm / W, at least 0.01 ppm / W, at least 0.02 ppm / W, at least 0.1 ppm / W, at least 0.5 ppm / W, or at least 1 ppm / W.

[0038] Preferably, F(644nm)<10 ppm / W. More preferably, F(644nm) is at most 9.5 ppm / W, more preferably at most 9 ppm / W, more preferably at most 8.5 ppm / W, more preferably at most 8 ppm / W, more preferably at most 7.5 ppm / W, more preferably at most 7 ppm / W, more preferably at most 6.5 ppm / W, more preferably at most 6 ppm / W, more preferably at most 5.5 ppm / W, more preferably at most 5 ppm / W, more preferably at most 4.5 ppm / W, more preferably at most 4 ppm / W, more preferably at most 3.5 ppm / W, more preferably at most 3 ppm / W, more preferably at most 2.75 ppm / W, more preferably at most 2.5 ppm / W, more preferably at most 2.25 ppm / W, more preferably at most 2 ppm / W, more preferably at most 1.75 ppm / W, more preferably at most 1.5 ppm / W, more preferably at most 1.25 ppm / W, more preferably at most 1 ppm / W. In some embodiments, F(546 nm) is at least 0.001 ppm / W, at least 0.005 ppm / W, at least 0.01 ppm / W, or at least 0.02 ppm / W, at least 0.1 ppm / W, at least 0.5 ppm / W, or at least 0.75 ppm / W.

[0039] Preferably, the beam guiding element therefore consists of glass having a quality factor F(RGB)=F(436nm)+F(546nm)+F(644nm)=S(436nm)×(Ext0(436nm)+Ext1(436nm)) / k+S(546nm)×(Ext0(546nm)+Ext1(546nm)) / k+S(644nm)×(Ext0(644nm)+Ext1(644nm)) / k and with F(RGB)<40ppm / W. Preferably, F(RGB) is at most 38.5 ppm / W, more preferably at most 37 ppm / W, more preferably at most 35.5 ppm / W, more preferably at most 34 ppm / W, more preferably at most 32.5 ppm / W, more preferably at most 31 ppm / W, more preferably at most 29.5 ppm / W, more preferably at most 28 ppm / W, more preferably at most 26.5 ppm / W, more preferably at most 25 ppm / W, more preferably at most 23.5 ppm / W, more preferably at most 22 ppm / W, more preferably at most 20.5 ppm / W, more preferably at most 19 ppm / W, more preferably at most 17.5 ppm / W, more preferably at most 16 ppm / W, more preferably at most 14.5 ppm / W, more preferably at most 13 ppm / W, more preferably at most 11.5 ppm / W, more preferably at most 10 ppm / W, more preferably at most 9 ppm / W, more preferably at most 8 ppm / W, more preferably at most 7 ppm / W, more preferably at most 6 ppm / W. In some embodiments, F(RGB) is at least 0.5 ppm / W, at least 1 ppm / W, at least 2 ppm / W, or at least 5 ppm / W.

[0040] The quantity that has a decisive influence on the quality factor F is the wavelength-dependent heating degree S(λ). Heating degree describes the relative change in the optical path s = (n-1) × d with respect to temperature T, where n is the refractive index and d is the sample thickness. S = 1 / s × ds / dT. Since d = d(T) and n = n(T), S = 1 / s × (dn / dT × d + (n-1)dd / dT). Therefore, S = 1 / (n-1) × dn / dT + 1 / d × dd / dT = 1 / (n-1) × dn / dT + CTE. CTE is the coefficient of thermal expansion.

[0041] The thermal expansion coefficient is preferably determined as described in DIN 51045-1:2005-08 and DIN ISO 7991 1998-02. Here, a glass sample of a defined length is prepared, and the relative change in length (dL / L) per temperature interval (dT) is measured in a dilatometer. The average thermal expansion coefficient in the temperature interval from -30°C to +70°C is preferably used to calculate the degree of heating S(λ). A low thermal expansion coefficient is advantageous, especially in the temperature range from -30°C to 70°C (CTE(-30 / 70)). Preferably, the CTE(-30 / 70) is in the range of 3.0 ppm / K to 14.0 ppm / K, in particular 4.0 ppm / K to 10.0 ppm / K, 4.5 ppm / K to 9.5 ppm / K, 5.0 ppm / K to 8.0 ppm / K, and / or 5.5 ppm / K to 7.5 ppm / K, for example 5.6 ppm / K to 7.3 ppm / K, or 5.7 ppm / K to 7.2 ppm / K.

[0042] The determination of dn / dT can be performed using a prism spectrometer (with all prisms) placed inside a temperature chamber. Measurements in a configuration with the smallest total deflection angle are preferred, since in this case the refractive index can be calculated using only the deflection angle and the known prism angle.

[0043] More preferably, the determination of dn / dT is carried out by the half-prism method. For this, a sample in the form of a half-prism is introduced into a temperature-controlled sample chamber. Light of different wavelengths is irradiated onto the prism, and the deflection angle is determined in each case. The temperature in the chamber is changed accordingly. This results in a refractive index value as a function of wavelength and temperature. For calculating the degree of heating S(λ), the average dn / dT in the temperature range +20°C to +40°C is preferably used. In order to minimize the magnitude of the thermal lens effect, it is advantageous if the change in refractive index with temperature (dn / dT) is as small as possible, especially in the temperature range 20°C to 40°C. Preferably, the average dn / dT at wavelengths of 436 nm, 546 nm, and / or 644 nm in the temperature range of 20°C to 40°C is in the range of 0.1 ppm / K to 8.0 ppm / K, particularly 0.2 ppm / K to 7.0 ppm / K, 0.3 ppm / K to 6.0 ppm / K, and / or 0.4 ppm / K to 5.0 ppm / K, where the numerical values are based on the absolute value (magnitude) of the average dn / dT.

[0044] As mentioned above, the induced absorption band causes a temperature rise inside the glass, which causes the refractive index and geometric path to change with temperature, resulting in wavefront retardation and undesirable imaging errors. Therefore, the change in the optical path with temperature (heating degree S) is preferably small. In this way, imaging errors can be minimized even in the presence of the induced absorption band.

[0045] Preferably, S(436nm) is at most 50 ppm / K, more preferably at most 30 ppm / K, more preferably at most 25 ppm / K, more preferably at most 20 ppm / K, more preferably at most 15 ppm / K, more preferably at most 10 ppm / K. In some embodiments, S(436nm) is at least 0.1 ppm / K, at least 0.5 ppm / K, at least 1 ppm / K, or at least 2 ppm / K.

[0046] Preferably, S(546nm) is at most 50 ppm / K, more preferably at most 30 ppm / K, more preferably at most 25 ppm / K, more preferably at most 20 ppm / K, more preferably at most 15 ppm / K, more preferably at most 10 ppm / K. In some embodiments, S(546nm) is at least 0.1 ppm / K, at least 0.5 ppm / K, at least 1 ppm / K, or at least 2 ppm / K.

[0047] Preferably, S(644nm) is at most 50 ppm / K, more preferably at most 30 ppm / K, more preferably at most 25 ppm / K, more preferably at most 20 ppm / K, more preferably at most 15 ppm / K, more preferably at most 10 ppm / K. In some embodiments, S(644nm) is at least 0.1 ppm / K, at least 0.5 ppm / K, at least 1 ppm / K, or at least 2 ppm / K.

[0048] Preferably, S(436 nm), S(546 nm), and S(644 nm) are at most 50 ppm / K, more preferably at most 30 ppm / K, more preferably at most 25 ppm / K, more preferably at most 20 ppm / K, more preferably at most 15 ppm / K, more preferably at most 10 ppm / K. In some embodiments, S(436 nm), S(546 nm), and S(644 nm) are at least 0.1 ppm / K, at least 0.5 ppm / K, at least 1 ppm / K, or at least 2 ppm / K.

[0049] Further important quantities are the uninduced absorbance Ext0 and the induced absorbance Ext1. Ext1(λ) describes the additional absorbance (compared to Ext0(λ)) per cm at wavelength λ after irradiation of the sample. The induced absorbance Ext1 depends, among other things, on the type of irradiation source. To assess the solarization stability of materials under high-intensity blue light irradiation, laser irradiation with a wavelength of 455 nm and an intensity of 345 W / cm was used. 2It has been found advantageous to perform irradiation for 72 hours at a power density of 1000 kJ / s. In order to achieve both high power density and uniform irradiation of the sample, an irradiation approach has been developed that utilizes the concept of optical waveguiding. Preferably, before irradiation, the sample is polished on all sides and the laser light is directed at the incident surface (preferably 4 × 4 mm) at an angle of total internal reflection (TIR). 2 ) is irradiated. This means that if a 55W laser is used, the 2 In this disclosure, "power density" refers to "input power density" unless otherwise specified.

[0050] According to the present invention, the induced absorbance Ext1(λ) is 345 W / cm induced by laser irradiation with a wavelength of 455 nm. 2 The uninduced absorbance Ext0(λ) describes the additional absorbance per cm at wavelength λ of a sample with a sample thickness d of 100 mm after irradiation for 72 hours at a power density of 100 mm. In contrast, the uninduced absorbance Ext0(λ) describes the absorbance per cm at wavelength λ of a sample with a sample thickness d of 100 mm before irradiation. The uninduced absorbance Ext0(λ) and the induced absorbance Ext1(λ) can be determined by examining the transmittance of the sample with a spectrophotometer before and after irradiation.

[0051] The sample size is preferably 100 mm x 4 mm x 4 mm, where the 100 mm dimension is referred to as the sample thickness d, as already mentioned above.

[0052] It is advantageous if Ext0 and Ext1 are low. The two values therefore contribute together to the quality factor F.

[0053] A low uninduced absorbance Ext0 is advantageous since it results in a low output absorbance, so to speak, without prior illumination.

[0054] A low induced absorbance Ext1 is also advantageous. This indicates that no excessive absorption occurs after irradiation, thereby providing a measure of solarization resistance. The absorbance Ext(λ) is written as the natural logarithm of the quotient of the incident radiation I0 of wavelength λ and the outgoing radiation I of wavelength λ as the dividend, and the sample thickness d as the divisor: Ext(λ) = In(I0 / I) / d. In this way, both Ext0 and Ext1 can be determined. As already mentioned above, the sample thickness d in the present invention is 100 mm.

[0055] Preferably, Ext0(436nm) is less than 0.01 / cm, more preferably at most 0.008 / cm, more preferably at most 0.005 / cm, more preferably at most 0.004 / cm, more preferably at most 0.003 / cm, more preferably at most 0.002 / cm. In some embodiments, Ext0(436nm) is at least 0.0001 / cm, at least 0.0002 / cm, at least 0.0003 / cm, or at least 0.0005 / cm.

[0056] Preferably, Ext0(546nm) is less than 0.01 / cm, more preferably at most 0.008 / cm, more preferably at most 0.005 / cm, more preferably at most 0.004 / cm, more preferably at most 0.003 / cm, more preferably at most 0.002 / cm, more preferably at most 0.0015 / cm, more preferably at most 0.001 / cm. In some embodiments, Ext0(546nm) is at least 0.0001 / cm, at least 0.0002 / cm, at least 0.0003 / cm, or at least 0.0005 / cm.

[0057] Preferably, Ext0(644nm) is less than 0.01 / cm, more preferably at most 0.008 / cm, more preferably at most 0.005 / cm, more preferably at most 0.004 / cm, more preferably at most 0.003 / cm, more preferably at most 0.002 / cm, more preferably less than 0.0015 / cm. In some embodiments, Ext0(644nm) is at least 0.0001 / cm, at least 0.0002 / cm, at least 0.0003 / cm, or at least 0.0005 / cm.

[0058] Preferably, Ext0(436nm), Ext0(546nm) and Ext0(644nm) are less than 0.01 / cm, more preferably at most 0.008 / cm, more preferably at most 0.005 / cm, more preferably at most 0.004 / cm, more preferably at most 0.003 / cm, more preferably at most 0.002 / cm. In some embodiments, Ext0(436nm), Ext0(546nm) and Ext0(644nm) are at least 0.0001 / cm, at least 0.0002 / cm, at least 0.0003 / cm, or at least 0.0005 / cm.

[0059] Preferably, Ext1 (436 nm) is less than 0.01 / cm, more preferably at most 0.0095 / cm, more preferably at most 0.009 / cm, more preferably at most 0.0085 / cm, more preferably at most 0.008 / cm, more preferably at most 0.0075 / cm, more preferably at most 0.007 / cm, more preferably at most 0.0065 / cm, more preferably at most 0.006 / cm, more preferably at most 0.0055 / cm, more preferably at most 0.005 / cm, more preferably at most 0.004 / cm, more preferably at most 0.0035 / cm, more preferably at most 0.003 / cm, more preferably at most 0.0025 / cm, more preferably at most 0.002 / cm, more preferably at most 0.0015 / cm. In some embodiments, Ext1 (436 nm) is at least 0.0001 / cm, at least 0.0002 / cm, at least 0.0005 / cm, at least 0.001 / cm, at least 0.0015 / cm, or at least 0.002 / cm.

[0060] Preferably, Ext1 (546 nm) is less than 0.01 / cm, more preferably at most 0.0095 / cm, more preferably at most 0.009 / cm, more preferably at most 0.0085 / cm, more preferably at most 0.008 / cm, more preferably at most 0.0075 / cm, more preferably at most 0.007 / cm, more preferably at most 0.0065 / cm, more preferably at most 0.006 / cm, more preferably at most 0.0055 / cm, more preferably at most 0.005 / cm, more preferably at most 0.0045 / cm, more preferably at most 0.004 / cm, more preferably at most 0.0035 / cm, more preferably at most 0.003 / cm, more preferably at most 0.0025 / cm, more preferably at most 0.002 / cm, more preferably at most 0.0015 / cm, more preferably at most 0.001 / cm. In some embodiments, Ext1(546 nm) is at least 0.0001 / cm, at least 0.0002 / cm, at least 0.0003 / cm, or at least 0.0005 / cm.

[0061] Preferably, Ext1(644nm) is less than 0.009 / cm, more preferably at most 0.0085 / cm, more preferably at most 0.008 / cm, more preferably at most 0.0075 / cm, more preferably at most 0.007 / cm, more preferably at most 0.0065 / cm, more preferably at most 0.006 / cm, more preferably at most 0.0055 / cm, more preferably at most 0.005 / cm, more preferably at most 0.0045 / cm, more preferably at most 0.004 / cm, more preferably at most 0.003 / cm, more preferably at most 0.002 / cm, more preferably at most 0.0015 / cm, more preferably at most 0.001 / cm, more preferably at most 0.0005 / cm. In some embodiments, Ext1(644nm) is at least 0.0001 / cm, at least 0.0002 / cm, at least 0.0003 / cm, or at least 0.0005 / cm.

[0062] Preferably, Ext1(436nm), Ext1(546nm) and Ext1(644nm) are less than 0.009 / cm, more preferably at most 0.0085 / cm, more preferably at most 0.008 / cm, more preferably at most 0.0075 / cm, more preferably at most 0.007 / cm, more preferably at most 0.0065 / cm, more preferably at most 0.006 / cm, more preferably at most 0.0055 / cm, more preferably at most 0.005 / cm, more preferably at most 0.0045 / cm, more preferably at most 0.004 / cm, more preferably at most 0.0035 / cm. In some embodiments, Ext1(436nm), Ext1(546nm) and Ext1(644nm) are at least 0.0001 / cm, at least 0.0002 / cm, at least 0.0003 / cm, or at least 0.0005 / cm.

[0063] It is particularly advantageous, especially for use in projectors, if the absorbances induced in the blue, green and red spectral regions are low in total. Preferably, Ext1(RGB)=Ext1(436 nm)+Ext1(546 nm)+Ext1(644 nm)<0.0310 / cm. More preferably, Ext1(RGB) is less than 0.03 / cm, more preferably at most 0.0275 / cm, more preferably at most 0.025 / cm, more preferably at most 0.0225 / cm, more preferably at most 0.02 / cm, more preferably at most 0.0175 / cm, more preferably at most 0.0153 / cm, more preferably at most 0.015 / cm, more preferably at most 0.0125 / cm, more preferably at most 0.01 / cm, more preferably at most 0.009 / cm, more preferably at most 0.008 / cm, more preferably at most 0.007 / cm, more preferably at most 0.0061 / cm, more preferably at most 0.006 / cm, more preferably at most 0.0057 / cm, more preferably at most 0.005 / cm, more preferably at most 0.004 / cm, more preferably at most 0.003 / cm, more preferably at most 0.0025 / cm, more preferably at most 0.002 / cm. In some embodiments, Ext1(RGB) is at least 0.0001 / cm, at least 0.0002 / cm, at least 0.0003 / cm, at least 0.0005 / cm, or at least 0.001 / cm.

[0064] Another important quantity is the thermal conductivity k. The thermal conductivity is the product of density, specific heat capacity, and thermal conductivity. The density is preferably determined according to Archimedes' principle (in particular ASTM C693:1993). To calculate the temperature dependence of the density, the expansion behavior is determined, preferably by dilatometry, as described in DIN 51045-1:2005-08 and DIN ISO 7991:1998-02. The specific heat capacity is preferably determined by DSC (dynamic differential scanning calorimetry) according to DIN 51007:2019-04. The thermal conductivity is preferably determined by flash analysis according to ASTM E1461:2013.

[0065] A high thermal conductivity k limits the steady-state temperature rise of the optical glass in the beam path. Preferably, the thermal conductivity k is greater than 0.005 W / (cm·K), more preferably at least 0.006 W / (cm·K), more preferably at least 0.007 W / (cm·K), more preferably at least 0.008 W / (cm·K), e.g., at least 0.009 W / (cm·K), or at least 0.010 W / (cm·K). In some embodiments, the thermal conductivity k is at most 0.050 W / (cm·K), at most 0.040 W / (cm·K), at most 0.030 W / (cm·K), at most 0.020 W / (cm·K), or at most 0.015 W / (cm·K).

[0066] As mentioned above, the beam guide element is made of glass that is particularly resistant to solarization under blue light irradiation. Such glass significantly reduces the occurrence of thermal lensing effects, which is advantageous for corresponding applications in projectors and material processing. Additionally, other aspects can also contribute to reducing thermal lensing effects. For example, for a given local thermal energy stored (by absorption of laser light), the steady-state temperature difference decreases as the thermal conductivity increases, and therefore the temperature-induced imaging errors also decrease. Therefore, a high thermal conductivity k is advantageous.

[0067] Depending on the application, the refractive index may also play a role. Preferably, the refractive index at wavelengths of 436 nm, 546 nm and / or 644 nm is in the range of 1.45 to 1.65.

[0068] It has been found that a variety of glass families can be used to obtain glasses having the quality factor according to the invention. The glasses are preferably selected from the group consisting of fluorophosphate glasses, silicate glasses, borosilicate glasses, niobium phosphate glasses, and aluminoborosilicate glasses. Particularly relevant factors include the fining agents used, as well as the purity of the raw materials used with respect to impurities, including MnO, as explained below.

[0069] Preferably, the beam guide element consists of glass containing the following components in the stated proportions (% by weight):

[0070] [Table 1] Here, the following condition is satisfied: (i) MnO2 content less than 1.0 ppm (by weight); (ii) at least 0.1 wt. % SnO2 component and at least 0.05 wt. % Cl component; (iii) at least 0.005 wt. % of a CeO2 component; At least one of the following is satisfied.

[0071] Preferably, at least two of the above conditions are satisfied. The glass may, for example, have an MnO2 content of less than 1.0 ppm and an SnO2 content of at least 0.1 wt% and an Cl content of at least 0.05 wt%. The glass may, for example, have an MnO2 content of less than 1.0 ppm and an CeO2 content of at least 0.005 wt%. The glass may, for example, have an SnO2 content of at least 0.1 wt% and an Cl content of at least 0.05 wt% and an CeO2 content of at least 0.005 wt%.

[0072] The glass may also have an MnO2 content of less than 1.0 ppm, an SnO2 content of at least 0.1 wt. %, a Cl content of at least 0.05 wt. %, and a CeO2 content of at least 0.005 wt. %.

[0073] The measures mentioned and combinations thereof have been found to provide advantages in terms of quality factor according to the invention.

[0074] Raw materials used in glass manufacture contain MnO as an impurity. Therefore, it is not possible to provide a glass completely free of MnO. However, the MnO impurity can be reduced by selecting raw materials. Commercially available raw materials consistently produce glasses with MnO contents exceeding 1.0 ppm. By selecting particularly pure raw materials, the MnO content can be reduced to values below 1.0 ppm. Preferably, the MnO content is at most 0.9 ppm, more preferably at most 0.8 ppm, more preferably at most 0.7 ppm, more preferably at most 0.6 ppm, more preferably at most 0.5 ppm, more preferably at most 0.4 ppm, more preferably at most 0.3 ppm, more preferably at most 0.2 ppm, more preferably at most 0.15 ppm, and more preferably at most 0.1 ppm. In embodiments of the present invention, the MnO content is at least 0.01 ppm, at least 0.02 ppm, or at least 0.05 ppm. The MnO2 component of the glass may be, for example, 0.01 ppm to less than 1.0 ppm, 0.01 ppm to 0.9 ppm, 0.01 ppm to 0.8 ppm, 0.01 ppm to 0.7 ppm, 0.01 ppm to 0.6 ppm, 0.01 ppm to 0.5 ppm, 0.01 ppm to 0.4 ppm, 0.01 ppm to 0.3 ppm, 0.01 ppm to 0.2 ppm, 0.01 ppm to 0.15 ppm, 0.01 ppm to 0.1 ppm, 0.02 ppm to less than 1.0 ppm, 0.02 ppm to 0.9 ppm, 0.02 ppm to 0.8 ppm, 0.02 ppm to 0.7 ppm, 0.02 ppm to 0.6 ppm, 0.0 It may be in the range of 2 ppm to 0.5 ppm, 0.02 ppm to 0.4 ppm, 0.02 ppm to 0.3 ppm, 0.02 ppm to 0.2 ppm, 0.02 ppm to 0.15 ppm, 0.02 ppm to 0.1 ppm, 0.05 ppm to less than 1.0 ppm, 0.05 ppm to 0.9 ppm, 0.05 ppm to 0.8 ppm, 0.05 ppm to 0.7 ppm, 0.05 ppm to 0.6 ppm, 0.05 ppm to 0.5 ppm, 0.05 ppm to 0.4 ppm, 0.05 ppm to 0.3 ppm, 0.05 ppm to 0.2 ppm, 0.05 ppm to 0.15 ppm, or 0.05 ppm to 0.1 ppm.

[0075] The quality factor can also be improved by Sn / Cl refining. A relatively high SnO2 content has proven particularly advantageous in this case. The SnO2 content of the glass is preferably at least 0.1 wt%, more preferably at least 0.15 wt%, more preferably at least 0.2 wt%, more preferably at least 0.25 wt%, more preferably at least 0.3 wt%, more preferably at least 0.35 wt%, and more preferably at least 0.4 wt%. The Cl content of the glass is preferably at least 0.05 wt%, more preferably at least 0.1 wt%. The glass preferably has at least 0.3 wt% SnO2 and at least 0.05 wt% Cl, more preferably at least 0.4 wt% SnO2 and at least 0.1 wt% Cl.

[0076] In embodiments of the present invention, the SnO content is at most 1.0 wt. % or at most 0.5 wt. % and / or the Cl content is at most 1.0 wt. % or at most 0.5 wt. The SnO content may be, for example, in the range of 0.1 wt. % to 1.0 wt. % and / or the Cl content may be in the range of 0.05 wt. % to 1.0 wt. Preferably, the SnO content is at most 1.0 wt. %, e.g., at most 0.75 wt. %, at most 0.5 wt. %, or at most 0.45 wt. If the SnO content is too high, the tendency to crystallize may increase. Preferably, the Cl content is at most 1.0 wt. %, e.g., at most 0.75 wt. %, at most 0.5 wt. %, at most 0.45 wt. If the Cl content is too high, corrosion of the vessel or instability of the glass may occur.

[0077] The ratio of the weight fraction of SnO2 to the weight fraction of Cl is preferably in the range of 1:5 to 5:1, for example, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, or 1:1.5 to 1.5:1. Thus, a particularly good quality factor can be achieved. Particularly preferably, the proportion of SnO2 is lower than the proportion of Cl.

[0078] CeO2 can also be used to improve the quality factor. CeO2 undesirably increases the Ext0 value. However, it has surprisingly been found that a low proportion of CeO2 improves solarization resistance by more than compensating for the increase in Ext0 value, thereby improving the quality factor. Preferably, the CeO2 content is at least 0.005 wt.%, more preferably at least 0.01 wt.%. Preferably, the CeO2 content is at most 0.05 wt.% or at most 0.04 wt.%. Preferably, the CeO2 content is in the range of 0.005 wt.% to 0.05 wt.%, for example, 0.01 wt.% to 0.04 wt.%.

[0079] In particular, in embodiments in which the glass contains at least 0.005% by weight or at least 0.01% by weight of CeO2, the glass preferably contains less than 0.3% by weight, more preferably at most 0.2% by weight, more preferably at most 0.1% by weight of TiO2, or particularly preferably is substantially free of TiO2.

[0080] The glass of the present invention may be, for example, a fluorophosphate glass. Particularly preferred fluorophosphate glasses of the present invention contain the following components in the stated proportions (by weight):

[0081] [Table 2] Here, the following condition is satisfied: (i) MnO2 content less than 1.0 ppm (by weight); (ii) at least 0.1 wt. % SnO2 component and at least 0.05 wt. % Cl component; (iii) at least 0.005 wt. % of a CeO2 component; At least one of the following is satisfied.

[0082] Preferably, at least two of the above conditions are satisfied. The fluorophosphate glass may, for example, have an MnO2 content of less than 1.0 ppm, an SnO2 content of at least 0.1 wt%, and an Cl content of at least 0.05 wt%. The fluorophosphate glass may, for example, have an MnO2 content of less than 1.0 ppm, and an CeO2 content of at least 0.005 wt%. The fluorophosphate glass may, for example, have an SnO2 content of at least 0.1 wt%, an Cl content of at least 0.05 wt%, and an CeO2 content of at least 0.005 wt%.

[0083] The fluorophosphate glass may also have an MnO2 content of less than 1.0 ppm, an SnO2 content of at least 0.1 wt. %, a Cl content of at least 0.05 wt. %, and a CeO2 content of at least 0.005 wt. %.

[0084] The measures mentioned and combinations thereof have been found to provide advantages in terms of quality factor according to the invention.

[0085] Raw materials used in glass manufacture contain MnO as an impurity. Therefore, it is not possible to provide a fluorophosphate glass completely free of MnO. However, the MnO impurity can be reduced by selecting the raw materials. Commercially available raw materials consistently produce glasses with an MnO content greater than 1.0 ppm. By selecting particularly pure raw materials, the MnO content can be reduced to values less than 1.0 ppm. Preferably, the MnO content is at most 0.9 ppm, more preferably at most 0.8 ppm, more preferably at most 0.7 ppm, more preferably at most 0.6 ppm, more preferably at most 0.5 ppm, more preferably at most 0.4 ppm, more preferably at most 0.3 ppm, more preferably at most 0.2 ppm, more preferably at most 0.15 ppm, and more preferably at most 0.1 ppm. In embodiments of the present invention, the MnO content is at least 0.01 ppm, at least 0.02 ppm, or at least 0.05 ppm. The MnO2 component of the fluorophosphate glass may be, for example, 0.01 ppm to less than 1.0 ppm, 0.01 ppm to 0.9 ppm, 0.01 ppm to 0.8 ppm, 0.01 ppm to 0.7 ppm, 0.01 ppm to 0.6 ppm, 0.01 ppm to 0.5 ppm, 0.01 ppm to 0.4 ppm, 0.01 ppm to 0.3 ppm, 0.01 ppm to 0.2 ppm, 0.01 ppm to 0.15 ppm, 0.01 ppm to 0.1 ppm, 0.02 ppm to less than 1.0 ppm, 0.02 ppm to 0.9 ppm, 0.02 ppm to 0.8 ppm, 0.02 ppm to 0.7 ppm, 0.02 ppm to 0.6 ppm, It may be in the range of 0.02 ppm to 0.5 ppm, 0.02 ppm to 0.4 ppm, 0.02 ppm to 0.3 ppm, 0.02 ppm to 0.2 ppm, 0.02 ppm to 0.15 ppm, 0.02 ppm to 0.1 ppm, 0.05 ppm to less than 1.0 ppm, 0.05 ppm to 0.9 ppm, 0.05 ppm to 0.8 ppm, 0.05 ppm to 0.7 ppm, 0.05 ppm to 0.6 ppm, 0.05 ppm to 0.5 ppm, 0.05 ppm to 0.4 ppm, 0.05 ppm to 0.3 ppm, 0.05 ppm to 0.2 ppm, 0.05 ppm to 0.15 ppm, or 0.05 ppm to 0.1 ppm.

[0086] The quality factor can also be improved by Sn / Cl refining. A relatively high SnO content has proven particularly advantageous in this case. The SnO content of the fluorophosphate glass is preferably at least 0.1 wt%, more preferably at least 0.15 wt%, more preferably at least 0.2 wt%, more preferably at least 0.25 wt%, more preferably at least 0.3 wt%, more preferably at least 0.35 wt%, and more preferably at least 0.4 wt%. The Cl content of the fluorophosphate glass is preferably at least 0.05 wt%, more preferably at least 0.1 wt%. The fluorophosphate glass preferably has at least 0.3 wt% SnO and at least 0.05 wt%, more preferably at least 0.4 wt% SnO and at least 0.1 wt% Cl. In embodiments of the present invention, the SnO content is at most 1.0 wt% or at most 0.5 wt%, and / or the Cl content is at most 1.0 wt% or at most 0.5 wt%. The SnO2 content may be, for example, in the range of 0.1 wt% to 1.0 wt%, and / or the Cl content may be in the range of 0.05 wt% to 1.0 wt%. Preferably, the SnO2 content is up to 1.0 wt%, e.g., up to 0.75 wt%, up to 0.5 wt%, or up to 0.45 wt%. If the SnO2 content is too high, the tendency to crystallize may increase. Preferably, the Cl content is up to 1.0 wt%, e.g., up to 0.75 wt%, up to 0.5 wt%, up to 0.45 wt%, or up to 0.4 wt%. If the Cl content is too high, corrosion of the bath may occur or the glass may become unstable.

[0087] The ratio of the proportion of SnO2 to the proportion of Cl is preferably in the range of 1:5 to 5:1, for example, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, or 1:1.5 to 1.5:1. Thus, a particularly good quality factor can be achieved. Particularly preferably, the proportion of SnO2 is lower than the proportion of Cl.

[0088] CeO2 can also be used to improve the quality factor. CeO2 undesirably increases the Ext0 value. However, it has surprisingly been found that a low proportion of CeO2 improves solarization resistance by more than compensating for the increase in Ext0 value, thereby improving the quality factor. Preferably, the CeO2 content is at least 0.005 wt.%, more preferably at least 0.01 wt.%. Preferably, the CeO2 content is at most 0.05 wt.% or at most 0.04 wt.%. Preferably, the CeO2 content is in the range of 0.005 wt.% to 0.05 wt.%, for example, 0.01 wt.% to 0.04 wt.%.

[0089] The fluorophosphate glasses of the present invention preferably contain less than 0.3 wt. %, more preferably at most 0.2 wt. %, and more preferably at most 0.1 wt. % of each of the components SiO2, BO3, Li2O, Na2O, KO, ZnO, TiO2, ZrO2, La2O3, Sb2O3, and As2O3, or are particularly preferably free of these components. In particular in embodiments in which the fluorophosphate glass contains at least 0.005 wt. % or at least 0.01 wt. % CeO2, the glass preferably contains less than 0.3 wt. %, more preferably at most 0.2 wt. %, more preferably at most 0.1 wt. % TiO2, or is particularly preferably substantially free of TiO2.

[0090] Preferably, the fluorophosphate glass contains 7.5 to 22.5% by weight of Al2O3, more preferably 10 to 20% by weight, and even more preferably 14 to 19% by weight. The Al2O3 content can be, for example, at least 7.5%, at least 10%, or at least 14% by weight. The Al2O3 content can be, for example, up to 22.5%, up to 20%, or up to 19% by weight.

[0091] Preferably, the fluorophosphate glass contains 1.5 to 7.5% by weight of MgO, more preferably 2 to 5% by weight, and even more preferably 2.5 to 3.5% by weight. The MgO content can be, for example, at least 1.5%, at least 2%, or at least 2.5% by weight. The MgO content can be, for example, up to 7.5%, up to 5%, or up to 3.5% by weight.

[0092] Preferably, the fluorophosphate glass contains 7.5 to 15 weight percent CaO, more preferably 9 to 14 weight percent CaO, and even more preferably 10 to 13 weight percent CaO. The CaO content can be, for example, at least 7.5 weight percent, at least 9 weight percent, or at least 10 weight percent. The MgO content can be, for example, at most 15 weight percent, at most 14 weight percent, or at most 13 weight percent.

[0093] Preferably, the fluorophosphate glass contains BaO in a proportion of 11 to 25% by weight, more preferably 12 to 20% by weight, and even more preferably 13 to 17% by weight. The BaO content may be, for example, at least 11% by weight, at least 12% by weight, or at least 13% by weight. The BaO content may be, for example, at most 25% by weight, at most 20% by weight, or at most 17% by weight.

[0094] Preferably, the fluorophosphate glass contains 15 to 24 weight percent SrO, more preferably 16 to 23 weight percent SrO, and even more preferably 16.5 to 22 weight percent SrO. The SrO content can be, for example, at least 15 weight percent, at least 16 weight percent, or at least 16.5 weight percent. The SrO content can be, for example, at most 24 weight percent, at most 23 weight percent, or at most 22 weight percent.

[0095] Preferably, the fluorophosphate glass contains 6 to 12 weight percent P2O5, more preferably 7 to 11 weight percent, and even more preferably 8 to 10 weight percent. The P2O5 content can be, for example, at least 6 weight percent, at least 7 weight percent, or at least 8 weight percent. The P2O5 content can be, for example, at most 12 weight percent, at most 11 weight percent, or at most 10 weight percent.

[0096] Preferably, the fluorophosphate glass contains 20 to 40% by weight of F, more preferably 25 to 35% by weight, and even more preferably 27.5 to 32.5% by weight. The F content may be, for example, at least 20% by weight, at least 25% by weight, or at least 27.5% by weight. The F content may be, for example, at most 40% by weight, at most 35% by weight, or at most 32.5% by weight.

[0097] The glass of the invention may be, for example, a silicate glass. Particularly preferred silicate glasses of the invention comprise the following components in the stated proportions (% by weight):

[0098] [Table 3] Here, the following condition is satisfied: (i) MnO2 content less than 1.0 ppm (by weight); (ii) at least 0.1 wt. % SnO2 component and at least 0.05 wt. % Cl component; (iii) at least 0.005 wt. % of a CeO2 component; At least one of the following is satisfied.

[0099] Preferably, at least two of the above conditions are satisfied. The silicate glass may, for example, have an MnO2 content of less than 1.0 ppm, an SnO2 content of at least 0.1 wt%, and an Cl content of at least 0.05 wt%. The silicate glass may, for example, have an MnO2 content of less than 1.0 ppm, and an CeO2 content of at least 0.005 wt%. The silicate glass may, for example, have an SnO2 content of at least 0.1 wt%, an Cl content of at least 0.05 wt%, and an CeO2 content of at least 0.005 wt%.

[0100] The silicate glass may also have an MnO2 content of less than 1.0 ppm, an SnO2 content of at least 0.1 wt. %, a Cl content of at least 0.05 wt. %, and a CeO2 content of at least 0.005 wt. %.

[0101] The measures mentioned and combinations thereof have been found to provide advantages in terms of quality factor according to the invention.

[0102] Raw materials used in glass production contain MnO as an impurity. Therefore, it is impossible to provide silicate glass completely free of MnO. However, the MnO impurity can be reduced by selecting raw materials. Commercially available raw materials consistently produce glasses with an MnO content greater than 1.0 ppm. By selecting particularly pure raw materials, the MnO content can be reduced to values less than 1.0 ppm. Preferably, the MnO content is at most 0.9 ppm, more preferably at most 0.8 ppm, more preferably at most 0.7 ppm, more preferably at most 0.6 ppm, more preferably at most 0.5 ppm, more preferably at most 0.4 ppm, more preferably at most 0.3 ppm, more preferably at most 0.2 ppm, more preferably at most 0.15 ppm, and more preferably at most 0.1 ppm. In embodiments of the present invention, the MnO content is at least 0.01 ppm, at least 0.02 ppm, or at least 0.05 ppm. The MnO2 component of silicate glass may be, for example, 0.01 ppm to less than 1.0 ppm, 0.01 ppm to 0.9 ppm, 0.01 ppm to 0.8 ppm, 0.01 ppm to 0.7 ppm, 0.01 ppm to 0.6 ppm, 0.01 ppm to 0.5 ppm, 0.01 ppm to 0.4 ppm, 0.01 ppm to 0.3 ppm, 0.01 ppm to 0.2 ppm, 0.01 ppm to 0.15 ppm, 0.01 ppm to 0.1 ppm, 0.02 ppm to less than 1.0 ppm, 0.02 ppm to 0.9 ppm, 0.02 ppm to 0.8 ppm, 0.02 ppm to 0.7 ppm, 0.02 ppm to 0.6 ppm, 0. The concentration may be in the range of 0.02 ppm to 0.5 ppm, 0.02 ppm to 0.4 ppm, 0.02 ppm to 0.3 ppm, 0.02 ppm to 0.2 ppm, 0.02 ppm to 0.15 ppm, 0.02 ppm to 0.1 ppm, 0.05 ppm to less than 1.0 ppm, 0.05 ppm to 0.9 ppm, 0.05 ppm to 0.8 ppm, 0.05 ppm to 0.7 ppm, 0.05 ppm to 0.6 ppm, 0.05 ppm to 0.5 ppm, 0.05 ppm to 0.4 ppm, 0.05 ppm to 0.3 ppm, 0.05 ppm to 0.2 ppm, 0.05 ppm to 0.15 ppm, or 0.05 ppm to 0.1 ppm.

[0103] The quality factor can also be improved by Sn / Cl refining. A relatively high SnO content has proven particularly advantageous in this case. The SnO content of the silicate glass is preferably at least 0.1 wt.%, more preferably at least 0.15 wt.%, more preferably at least 0.2 wt.%, more preferably at least 0.25 wt.%, more preferably at least 0.3 wt.%, more preferably at least 0.35 wt.%, and more preferably at least 0.4 wt.%. The Cl content of the silicate glass is preferably at least 0.05 wt.%, more preferably at least 0.1 wt.%. The silicate glass preferably has at least 0.3 wt.% SnO and at least 0.05 wt.% Cl, more preferably at least 0.4 wt.% SnO and at least 0.1 wt.% Cl. In embodiments of the present invention, the SnO content is at most 1.0 wt.% or at most 0.5 wt.% and / or the Cl content is at most 1.0 wt.% or at most 0.5 wt.%. The SnO2 content may be, for example, in the range of 0.1 wt% to 1.0 wt%, and / or the Cl content may be in the range of 0.05 wt% to 1.0 wt%. Preferably, the SnO2 content is up to 1.0 wt%, e.g., up to 0.75 wt%, up to 0.5 wt%, or up to 0.45 wt%. If the SnO2 content is too high, the tendency to crystallize may increase. Preferably, the Cl content is up to 1.0 wt%, e.g., up to 0.75 wt%, up to 0.5 wt%, up to 0.45 wt%, or up to 0.4 wt%. If the Cl content is too high, corrosion of the bath may occur or the glass may become unstable.

[0104] The ratio of the weight fraction of SnO2 to the weight fraction of Cl is preferably in the range of 1:5 to 5:1, for example, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, or 1:1.5 to 1.5:1. Thus, a particularly good quality factor can be achieved. Particularly preferably, the proportion of SnO2 is lower than the proportion of Cl.

[0105] CeO2 can also be used to improve the quality factor. CeO2 undesirably increases the Ext0 value. However, it has surprisingly been found that a low proportion of CeO2 improves solarization resistance by more than compensating for the increase in Ext0 value, thereby improving the quality factor. Preferably, the CeO2 content is at least 0.005 wt.%, more preferably at least 0.01 wt.%. Preferably, the CeO2 content is at most 0.05 wt.% or at most 0.04 wt.%. Preferably, the CeO2 content is in the range of 0.005 wt.% to 0.05 wt.%, for example, 0.01 wt.% to 0.04 wt.%.

[0106] The silicate glass of the present invention preferably contains less than 0.3 wt. %, more preferably at most 0.2 wt. %, more preferably at most 0.1 wt. % of each of the components B2O3, Al2O3, MgO, CaO, SrO, TiO2, P2O5, F, Sb2O3, and As2O3, or is particularly preferably free of these components. In particular in embodiments where the silicate glass contains at least 0.005 wt. % or at least 0.01 wt. % CeO2, the glass preferably contains less than 0.3 wt. %, more preferably at most 0.2 wt. %, more preferably at most 0.1 wt. % TiO2, or is particularly preferably substantially free of TiO2.

[0107] Preferably, the silicate glass contains 35 to 50% by weight of SiO2, more preferably 37.5 to 47.5% by weight, and even more preferably 40 to 45% by weight. The SiO2 content can be, for example, at least 35% by weight, at least 37.5% by weight, or at least 40% by weight. The SiO2 content can be, for example, up to 50% by weight, up to 47.5% by weight, or up to 45% by weight.

[0108] Preferably, the silicate glass contains 0.2 to 4 weight percent LiO, more preferably 0.4 to 2 weight percent LiO, and even more preferably 0.5 to 1.5 weight percent LiO. The LiO content can be, for example, at least 0.2 weight percent, at least 0.4 weight percent, or at least 0.5 weight percent. The LiO content can be, for example, up to 4 weight percent, up to 2 weight percent, or up to 1.5 weight percent.

[0109] Preferably, the silicate glass contains 2 to 15% by weight of NaO, more preferably 3 to 10% by weight, and even more preferably 4 to 7.5% by weight. The NaO content can be, for example, at least 2%, at least 3%, or at least 4% by weight. The NaO content can be, for example, up to 15%, up to 10%, or up to 7.5% by weight.

[0110] Preferably, the silicate glass contains KO in an amount of 1 to 10% by weight, more preferably 1.5 to 7.5% by weight, and even more preferably 2 to 5% by weight. The KO content may be, for example, at least 1% by weight, at least 1.5% by weight, or at least 2% by weight. The KO content may be, for example, at most 10% by weight, at most 7.5% by weight, or at most 5% by weight.

[0111] The total amount of alkali metal oxide (RO) components in the silicate glass is preferably in the range of 1 wt. % to 20 wt. %, more preferably 2 wt. % to 15 wt. %, and more preferably 5 wt. % to 12.5 wt. The RO component can be, for example, at least 1 wt. %, at least 2 wt. %, or at least 5 wt. The RO component can be, for example, up to 20 wt. %, up to 15 wt. %, or up to 12.5 wt. The glass preferably does not contain any other alkali metal oxides other than LiO, NaO, and / or KO.

[0112] Preferably, the silicate glass contains BaO in a proportion of 2 to 25% by weight, more preferably 5 to 20% by weight, and even more preferably 7.5 to 15% by weight. The BaO content may be, for example, at least 2% by weight, at least 5% by weight, or at least 7.5% by weight. The BaO content may be, for example, at most 25% by weight, at most 20% by weight, or at most 15% by weight.

[0113] Preferably, the silicate glass contains ZnO in a proportion of 5 to 30% by weight, more preferably 10 to 27.5% by weight, and even more preferably 15 to 25% by weight. The ZnO content may be, for example, at least 5% by weight, at least 10% by weight, or at least 15% by weight. The ZnO content may be, for example, up to 30% by weight, up to 27.5% by weight, or up to 25% by weight.

[0114] Preferably, the silicate glass contains 1.5 to 10 weight percent ZrO2, more preferably 2 to 8.5 weight percent ZrO2, and even more preferably 3 to 7 weight percent ZrO2. The ZrO2 content can be, for example, at least 1.5 weight percent, at least 2 weight percent, or at least 3 weight percent. The ZrO2 content can be, for example, up to 10 weight percent, up to 8.5 weight percent, or up to 7 weight percent.

[0115] Preferably, the silicate glass contains La2O3 in a proportion of 2 to 20 wt%, more preferably 5 to 15 wt%, and even more preferably 7.5 to 12.5 wt%. The La2O3 component can be, for example, at least 2 wt%, at least 5 wt%, or at least 7.5 wt%. The La2O3 component can be, for example, up to 20 wt%, up to 15 wt%, or up to 12.5 wt%.

[0116] The glass of the present invention may be, for example, a borosilicate glass. Particularly preferred borosilicate glasses of the present invention comprise the following components in the stated proportions (by weight):

[0117] [Table 4] Here, the following condition is satisfied: (i) MnO2 content less than 1.0 ppm (by weight); (ii) at least 0.1 wt. % SnO2 component and at least 0.05 wt. % Cl component; (iii) at least 0.005 wt. % of a CeO2 component; At least one of the following is satisfied.

[0118] Preferably, at least two of the above conditions are satisfied. The borosilicate glass may, for example, have an MnO2 content of less than 1.0 ppm, an SnO2 content of at least 0.1 wt%, and an Cl content of at least 0.05 wt%. The borosilicate glass may, for example, have an MnO2 content of less than 1.0 ppm, and an CeO2 content of at least 0.005 wt%. The borosilicate glass may, for example, have an SnO2 content of at least 0.1 wt%, an Cl content of at least 0.05 wt%, and an CeO2 content of at least 0.005 wt%.

[0119] The borosilicate glass may also have an MnO2 content of less than 1.0 ppm, an SnO2 content of at least 0.1 wt. %, a Cl content of at least 0.05 wt. %, and a CeO2 content of at least 0.005 wt. %.

[0120] The measures mentioned and combinations thereof have been found to provide advantages in terms of quality factor according to the invention.

[0121] Raw materials used in glass production contain MnO as an impurity. Therefore, it is not possible to provide borosilicate glass completely free of MnO. However, the MnO impurity can be reduced by selecting raw materials. Commercially available raw materials consistently produce glasses with MnO contents exceeding 1.0 ppm. By selecting particularly pure raw materials, the MnO content can be reduced to values below 1.0 ppm. Preferably, the MnO content is at most 0.9 ppm, more preferably at most 0.8 ppm, more preferably at most 0.7 ppm, more preferably at most 0.6 ppm, more preferably at most 0.5 ppm, more preferably at most 0.4 ppm, more preferably at most 0.3 ppm, more preferably at most 0.2 ppm, more preferably at most 0.15 ppm, and more preferably at most 0.1 ppm. In embodiments of the present invention, the MnO content is at least 0.01 ppm, at least 0.02 ppm, or at least 0.05 ppm. The MnO2 component of borosilicate glass may be, for example, 0.01 ppm to less than 1.0 ppm, 0.01 ppm to 0.9 ppm, 0.01 ppm to 0.8 ppm, 0.01 ppm to 0.7 ppm, 0.01 ppm to 0.6 ppm, 0.01 ppm to 0.5 ppm, 0.01 ppm to 0.4 ppm, 0.01 ppm to 0.3 ppm, 0.01 ppm to 0.2 ppm, 0.01 ppm to 0.15 ppm, 0.01 ppm to 0.1 ppm, 0.02 ppm to less than 1.0 ppm, 0.02 ppm to 0.9 ppm, 0.02 ppm to 0.8 ppm, 0.02 ppm to 0.7 ppm, 0.02 ppm to 0.6 ...5 ppm, 0.01 ppm to 0.6 ppm, 0.01 ppm to 0.5 ppm, 0.01 ppm to 0.6 ppm, 0.01 ppm to 0.5 ppm, 0.01 ppm to 0.6 ppm, 0.01 ppm to 0.5 ppm, 0.0 The concentration may be in the range of 0.02 ppm to 0.5 ppm, 0.02 ppm to 0.4 ppm, 0.02 ppm to 0.3 ppm, 0.02 ppm to 0.2 ppm, 0.02 ppm to 0.15 ppm, 0.02 ppm to 0.1 ppm, 0.05 ppm to less than 1.0 ppm, 0.05 ppm to 0.9 ppm, 0.05 ppm to 0.8 ppm, 0.05 ppm to 0.7 ppm, 0.05 ppm to 0.6 ppm, 0.05 ppm to 0.5 ppm, 0.05 ppm to 0.4 ppm, 0.05 ppm to 0.3 ppm, 0.05 ppm to 0.2 ppm, 0.05 ppm to 0.15 ppm, or 0.05 ppm to 0.1 ppm.

[0122] The quality factor can also be improved by Sn / Cl refining. A relatively high SnO content has proven particularly advantageous in this case. The SnO content of the borosilicate glass is preferably at least 0.1 wt.%, more preferably at least 0.15 wt.%, more preferably at least 0.2 wt.%, more preferably at least 0.25 wt.%, more preferably at least 0.3 wt.%, more preferably at least 0.35 wt.%, and more preferably at least 0.4 wt.%. The Cl content of the borosilicate glass is preferably at least 0.05 wt.%, more preferably at least 0.1 wt.%. The borosilicate glass preferably has at least 0.3 wt.% SnO and at least 0.05 wt.% Cl, more preferably at least 0.4 wt.% SnO and at least 0.1 wt.% Cl. In embodiments of the present invention, the SnO content is at most 1.0 wt.% or at most 0.5 wt.% and / or the Cl content is at most 1.0 wt.% or at most 0.5 wt.%. The SnO2 content may be, for example, in the range of 0.1 wt% to 1.0 wt%, and / or the Cl content may be in the range of 0.05 wt% to 1.0 wt%. Preferably, the SnO2 content is up to 1.0 wt%, e.g., up to 0.75 wt%, up to 0.5 wt%, or up to 0.45 wt%. If the SnO2 content is too high, the tendency to crystallize may increase. Preferably, the Cl content is up to 1.0 wt%, e.g., up to 0.75 wt%, up to 0.5 wt%, up to 0.45 wt%, or up to 0.4 wt%. If the Cl content is too high, corrosion of the bath may occur or the glass may become unstable.

[0123] The ratio of the weight fraction of SnO2 to the weight fraction of Cl is preferably in the range of 1:5 to 5:1, for example, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, or 1:1.5 to 1.5:1. Thus, a particularly good quality factor can be achieved. Particularly preferably, the proportion of SnO2 is lower than the proportion of Cl.

[0124] CeO2 can also be used to improve the quality factor. CeO2 undesirably increases the Ext0 value. However, it has surprisingly been found that a low proportion of CeO2 improves solarization resistance by more than compensating for the increase in Ext0 value, thereby improving the quality factor. Preferably, the CeO2 content is at least 0.005 wt.%, more preferably at least 0.01 wt.%. Preferably, the CeO2 content is at most 0.05 wt.% or at most 0.04 wt.%. Preferably, the CeO2 content is in the range of 0.005 wt.% to 0.05 wt.%, for example, 0.01 wt.% to 0.04 wt.%.

[0125] The borosilicate glass of the present invention preferably contains less than 0.3 wt. %, more preferably at most 0.2 wt. %, more preferably at most 0.1 wt. % of each of the components Al2O3, Li2O, MgO, ZnO, SrO, ZrO2, La2O3, P2O5, and As2O3, or is particularly preferably free of these components. In particular in embodiments where the borosilicate glass contains at least 0.005 wt. % or at least 0.01 wt. % CeO2, the glass preferably contains less than 0.3 wt. %, more preferably at most 0.2 wt. %, more preferably at most 0.1 wt. % TiO2, or is particularly preferably substantially free of TiO2.

[0126] Preferably, the borosilicate glass contains 52.5 to 77.5% by weight of SiO2, more preferably 55 to 75% by weight, and even more preferably 57.5 to 72.5% by weight. The SiO2 content can be, for example, at least 52.5% by weight, at least 55% by weight, or at least 57.5% by weight. The SiO2 content can be, for example, up to 77.5% by weight, up to 75% by weight, or up to 72.5% by weight.

[0127] Preferably, the borosilicate glass contains 5 to 25% by weight of B2O3, more preferably 7.5 to 20% by weight, and even more preferably 9 to 19% by weight. The B2O3 content can be, for example, at least 5% by weight, at least 7.5% by weight, or at least 9% by weight. The B2O3 content can be, for example, up to 25% by weight, up to 20% by weight, or up to 19% by weight.

[0128] Preferably, the borosilicate glass contains 0 to 17.5% by weight of NaO, more preferably 0 to 15% by weight, and even more preferably 9 to 12.5% by weight. In certain embodiments, the glass contains at least 2%, at least 5%, or at least 8% by weight of NaO. The NaO content can be, for example, up to 17.5%, up to 15%, or up to 12.5% by weight.

[0129] Preferably, the borosilicate glass contains 2 to 24% by weight of K2O, more preferably 4 to 23% by weight, and even more preferably 6 to 22% by weight. The K2O content may be, for example, at least 2% by weight, at least 4% by weight, or at least 6% by weight. The K2O content may be, for example, up to 24% by weight, up to 23% by weight, or up to 22% by weight.

[0130] Preferably, the total amount of alkali metal oxide (RO) components in the borosilicate glass is in the range of 5 wt% to 30 wt%, more preferably 10 wt% to 25 wt%, and more preferably 15 wt% to 22 wt%. The RO component can be, for example, at least 5 wt%, at least 10 wt%, or at least 15 wt%. The RO component can be, for example, up to 30 wt%, up to 25 wt%, or up to 22 wt%. The glass preferably does not contain any other alkali metal oxides other than NaO and / or KO.

[0131] Preferably, the borosilicate glass contains 0 to 5 wt. % CaO, more preferably 0 to 2 wt. % CaO, and even more preferably 0 to 1 wt. % CaO. In certain embodiments, the glass contains at least 0.1 wt. % CaO or at least 0.2 wt. % CaO. The CaO content can be, for example, up to 5 wt. %, up to 2 wt. %, or up to 1 wt. % CaO.

[0132] Preferably, the borosilicate glass contains 0 to 5 wt. % BaO, more preferably 0 to 3.5 wt. % BaO, and even more preferably 0 to 2 wt. In certain embodiments, the glass contains at least 0.1 wt. % BaO. The BaO content can be, for example, up to 5 wt. %, up to 3.5 wt. %, or up to 2 wt. % BaO.

[0133] Preferably, the borosilicate glass contains 0 to 2 wt. % TiO2, more preferably 0 to 1 wt. % TiO2, and even more preferably 0 to 0.5 wt. % TiO2. In certain embodiments, the glass contains at least 0.1 wt. % TiO2. The TiO2 content can be, for example, up to 2 wt. %, up to 1 wt. %, or up to 0.5 wt. % TiO2.

[0134] Preferably, the borosilicate glass contains 0 to 15 wt. % F, more preferably 0 to 12.5 wt. % F, and even more preferably 0 to 10 wt. % F. In certain embodiments, the glass contains at least 1 wt. %, at least 2 wt. % F, or at least 5 wt. % F. The F content can be, for example, up to 15 wt. %, up to 12.5 wt. % F, or up to 10 wt. % F.

[0135] The borosilicate glass may contain Sb2O3 in a proportion of 0.01% to 0.45% by weight, more preferably 0.01% to 0.4% by weight, and more preferably 0.01% to 0.35% by weight.

[0136] The glass of the present invention may be, for example, an aluminoborosilicate glass. Particularly preferred aluminoborosilicate glasses of the present invention comprise the following components in the stated proportions (by weight):

[0137] [Table 5] Here, the following condition is satisfied: (i) MnO2 content less than 1.0 ppm (by weight); (ii) at least 0.1 wt. % SnO2 component and at least 0.05 wt. % Cl component; (iii) at least 0.005 wt. % of a CeO2 component; At least one of the following is satisfied.

[0138] Preferably, at least two of the above conditions are satisfied. The aluminoborosilicate glass may, for example, have an MnO content of less than 1.0 ppm, and at least 0.1 wt. % SnO content and at least 0.05 wt. % Cl content. The aluminoborosilicate glass may, for example, have an MnO content of less than 1.0 ppm, and at least 0.005 wt. % CeO content. The aluminoborosilicate glass may, for example, have an SnO content of at least 0.1 wt. % SnO content, at least 0.05 wt. % Cl content, and at least 0.005 wt. % CeO content.

[0139] The aluminoborosilicate glass may also have an MnO2 content of less than 1.0 ppm, an SnO2 content of at least 0.1 wt. %, a Cl content of at least 0.05 wt. %, and a CeO2 content of at least 0.005 wt. %.

[0140] The measures mentioned and combinations thereof have been found to provide advantages in terms of quality factor according to the invention.

[0141] Raw materials used in glass manufacture contain MnO as an impurity. Therefore, it is not possible to provide aluminoborosilicate glass completely free of MnO. However, the MnO impurity can be reduced by selecting raw materials. Commercially available raw materials consistently produce glasses with MnO contents exceeding 1.0 ppm. By selecting particularly pure raw materials, the MnO content can be reduced to values below 1.0 ppm. Preferably, the MnO content is at most 0.9 ppm, more preferably at most 0.8 ppm, more preferably at most 0.7 ppm, more preferably at most 0.6 ppm, more preferably at most 0.5 ppm, more preferably at most 0.4 ppm, more preferably at most 0.3 ppm, more preferably at most 0.2 ppm, more preferably at most 0.15 ppm, and more preferably at most 0.1 ppm. In embodiments of the present invention, the MnO content is at least 0.01 ppm, at least 0.02 ppm, or at least 0.05 ppm. The MnO2 component of the aluminoborosilicate glass may be, for example, 0.01 ppm to less than 1.0 ppm, 0.01 ppm to 0.9 ppm, 0.01 ppm to 0.8 ppm, 0.01 ppm to 0.7 ppm, 0.01 ppm to 0.6 ppm, 0.01 ppm to 0.5 ppm, 0.01 ppm to 0.4 ppm, 0.01 ppm to 0.3 ppm, 0.01 ppm to 0.2 ppm, 0.01 ppm to 0.15 ppm, 0.01 ppm to 0.1 ppm, 0.02 ppm to less than 1.0 ppm, 0.02 ppm to 0.9 ppm, 0.02 ppm to 0.8 ppm, 0.02 ppm to 0.7 ppm, 0.02 ppm to 0.6 ppm. , 0.02 ppm to 0.5 ppm, 0.02 ppm to 0.4 ppm, 0.02 ppm to 0.3 ppm, 0.02 ppm to 0.2 ppm, 0.02 ppm to 0.15 ppm, 0.02 ppm to 0.1 ppm, 0.05 ppm to less than 1.0 ppm, 0.05 ppm to 0.9 ppm, 0.05 ppm to 0.8 ppm, 0.05 ppm to 0.7 ppm, 0.05 ppm to 0.6 ppm, 0.05 ppm to 0.5 ppm, 0.05 ppm to 0.4 ppm, 0.05 ppm to 0.3 ppm, 0.05 ppm to 0.2 ppm, 0.05 ppm to 0.15 ppm, or 0.05 ppm to 0.1 ppm.

[0142] The quality factor can also be improved by Sn / Cl refining. A relatively high SnO content has proven particularly advantageous in this case. The SnO content of the aluminoborosilicate glass is preferably at least 0.1 wt%, more preferably at least 0.15 wt%, more preferably at least 0.2 wt%, more preferably at least 0.25 wt%, more preferably at least 0.3 wt%, more preferably at least 0.35 wt%, and more preferably at least 0.4 wt%. The Cl content of the aluminoborosilicate glass is preferably at least 0.05 wt%, more preferably at least 0.1 wt%. The aluminoborosilicate glass preferably has at least 0.3 wt% SnO and at least 0.05 wt%, more preferably at least 0.4 wt% SnO and at least 0.1 wt% Cl. In embodiments of the present invention, the SnO content is at most 1.0 wt% or at most 0.5 wt%, and / or the Cl content is at most 1.0 wt% or at most 0.5 wt%. The SnO2 content may be, for example, in the range of 0.1 wt% to 1.0 wt%, and / or the Cl content may be in the range of 0.05 wt% to 1.0 wt%. Preferably, the SnO2 content is up to 1.0 wt%, e.g., up to 0.75 wt%, up to 0.5 wt%, or up to 0.45 wt%. If the SnO2 content is too high, the tendency to crystallize may increase. Preferably, the Cl content is up to 1.0 wt%, e.g., up to 0.75 wt%, up to 0.5 wt%, up to 0.45 wt%, or up to 0.4 wt%. If the Cl content is too high, corrosion of the bath may occur or the glass may become unstable.

[0143] The ratio of the weight fraction of SnO2 to the weight fraction of Cl is preferably in the range of 1:5 to 5:1, for example, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, or 1:1.5 to 1.5:1. Thus, a particularly good quality factor can be achieved. Particularly preferably, the proportion of SnO2 is lower than the proportion of Cl.

[0144] CeO2 can also be used to improve the quality factor. CeO2 undesirably increases the Ext0 value. However, it has surprisingly been found that a low proportion of CeO2 improves solarization resistance by more than compensating for the increase in Ext0 value, thereby improving the quality factor. Preferably, the CeO2 content is at least 0.005 wt.%, more preferably at least 0.01 wt.%. Preferably, the CeO2 content is at most 0.05 wt.% or at most 0.04 wt.%. Preferably, the CeO2 content is in the range of 0.005 wt.% to 0.05 wt.%, for example, 0.01 wt.% to 0.04 wt.%.

[0145] The aluminoborosilicate glass of the present invention preferably contains less than 0.3 wt. %, more preferably at most 0.2 wt. %, more preferably at most 0.1 wt. % of each of the components LiO, MgO, CaO, SrO, TiO, ZrO, LaO, P0, and AsO, or is particularly preferably free of these components. In particular in embodiments in which the aluminoborosilicate glass contains at least 0.005 wt. % or at least 0.01 wt. % CeO, the glass preferably contains less than 0.3 wt. %, more preferably at most 0.2 wt. %, more preferably at most 0.1 wt. % TiO, or is particularly preferably substantially free of TiO.

[0146] Preferably, the aluminoborosilicate glass contains 62.5 to 77.5% by weight of SiO, more preferably 65 to 75% by weight, and even more preferably 67.5 to 72.5% by weight. The SiO content can be, for example, at least 62.5% by weight, at least 65% by weight, or at least 67.5% by weight. The SiO content can be, for example, up to 77.5% by weight, up to 75% by weight, or up to 72.5% by weight.

[0147] Preferably, the aluminoborosilicate glass contains 7.5 to 25% by weight of B2O3, more preferably 10 to 20% by weight, and even more preferably 12.5 to 17.5% by weight. The B2O3 content can be, for example, at least 7.5% by weight, at least 10% by weight, or at least 12.5% by weight. The B2O3 content can be, for example, up to 25% by weight, up to 20% by weight, or up to 17.5% by weight.

[0148] Preferably, the aluminoborosilicate glass contains 0.2 to 10% by weight of NaO, more preferably 0.5 to 5% by weight, and even more preferably 1 to 3% by weight. The NaO content may be, for example, at least 0.2% by weight, at least 0.5% by weight, or at least 1% by weight. The NaO content may be, for example, up to 10% by weight, up to 5% by weight, or up to 3% by weight.

[0149] Preferably, the aluminoborosilicate glass contains 2 to 17.5% by weight of K2O, more preferably 5 to 15% by weight, and even more preferably 10 to 14% by weight. The K2O content may be, for example, at least 2% by weight, at least 5% by weight, or at least 10% by weight. The K2O content may be, for example, up to 17.5% by weight, up to 15% by weight, or up to 14% by weight.

[0150] Preferably, the total amount of alkali metal oxide (RO) components in the aluminoborosilicate glass is in the range of 2 wt% to 25 wt%, more preferably 5 wt% to 20 wt%, and more preferably 10 wt% to 15 wt%. The RO component can be, for example, at least 2 wt%, at least 5 wt%, or at least 10 wt%. The RO component can be, for example, up to 25 wt%, up to 20 wt%, or up to 15 wt%. The glass preferably does not contain any other alkali metal oxides other than NaO and / or KO.

[0151] Preferably, the aluminoborosilicate glass contains BaO in an amount of 0.02 to 5% by weight, more preferably 0.05 to 2% by weight, and even more preferably 0.1 to 1% by weight. The BaO content may be, for example, at least 0.02% by weight, at least 0.05% by weight, or at least 0.1% by weight. The BaO content may be, for example, at most 5% by weight, at most 2% by weight, or at most 1% by weight.

[0152] Preferably, the aluminoborosilicate glass contains ZnO in a proportion of 0.05 to 5 weight percent, more preferably 0.1 to 2 weight percent, and even more preferably 0.15 to 1 weight percent. The ZnO content may be, for example, at least 0.05 weight percent, at least 0.1 weight percent, or at least 0.15 weight percent. The ZnO content may be, for example, at most 5 weight percent, at most 2 weight percent, or at most 1 weight percent.

[0153] Preferably, the aluminoborosilicate glass contains 0.1 to 5% by weight of F, more preferably 0.2 to 2% by weight, and even more preferably 0.5 to 1.5% by weight. The F content may be, for example, at least 0.1% by weight, at least 0.2% by weight, or at least 0.5% by weight. The F content may be, for example, at most 5%, at most 2%, or at most 1.5% by weight.

[0154] The aluminoborosilicate glass may contain Sb2O3 in a proportion of 0.02 to 0.45% by weight, more preferably 0.05 to 0.4% by weight, and even more preferably 0.1 to 0.35% by weight.

[0155] The fining agent used is of particular importance, regardless of the glass system used, so the following statements apply to all glass families.

[0156] Sn / Cl refining is preferred. It has been found that particularly good quality factors can be achieved with Sn / Cl refining. The ratio of the weight percentage of SnO2 to the weight percentage of Cl is preferably in the range of 1:5 to 5:1, for example, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, or 1:1.5 to 1.5:1. Particularly preferably, the percentage of SnO2 is less than the percentage of Cl. The respective values given here refer to the percentages in the glass, not the composite. In the case of Cl, its percentage in the composite composition is generally higher than its percentage in the glass, because Cl evaporates during production. Particularly important with respect to the quality factor is the ratio of the percentage of SnO2 to the percentage of Cl in the glass. This can be adjusted, in particular, depending on the Cl content in the composite composition and the implementation of the method.

[0157] Preferably, the proportion of As2O3 in the glass according to the invention is less than 0.3% by weight, preferably at most 0.2% by weight, more preferably at most 0.1% by weight. Even more preferably, the glass is free of As2O3, which makes it possible to achieve particularly low Ext1 values.

[0158] Preferably, the proportion of Sb2O3 in the glass of the invention is at most 0.5% by weight, preferably at most 0.4% by weight, more preferably at most 0.3% by weight, for example at most 0.2% by weight, or at most 0.1% by weight. The glass may be substantially free of Sb2O3. This allows particularly low Ext1 values to be achieved.

[0159] Preferably, the total proportion of As2O3 + Sb2O3 is at most 0.5% by weight, preferably at most 0.4% by weight, more preferably at most 0.3% by weight, for example at most 0.2% by weight or at most 0.1% by weight. The glass may be substantially free of As2O3 and Sb2O3. This allows particularly low Ext1 values to be achieved.

[0160] The glass can contain, for example, 0 to 45% by weight, particularly 0.5 to 42.5% by weight or 5 to 40% by weight, of F. This makes it possible to achieve a particularly low Ext1 value.

[0161] The glass may also contain Cl, particularly based on Cl refinement. The Cl content is preferably less than 2 wt. %, preferably less than 1.5 wt. %, more preferably less than 1 wt. Too much Cl may cause undesirable salt precipitation on the glass.

[0162] As used herein, when a glass is said to be free of a component or to be free of a particular component, this means that the component may be present in the glass at most as an impurity. This means that the component is not added in a substantial amount. In the context of the present invention, an insubstantial amount is, in each case, less than 500 ppm, preferably less than 300 ppm, preferably less than 100 ppm, more preferably less than 50 ppm, and most preferably less than 10 ppm, by weight.

[0163] The present invention also relates to a beam guiding element made of a glass having a quality factor according to the invention and / or an induced absorbance Ext1 according to the invention. In particular, the present invention relates to a beam guiding element made of a glass having a quality factor F(436 nm) = S(436 nm) x (Ext0(436 nm) + Ext1(436 nm)) / k, where F(436 nm) < 15 ppm / W. The invention also relates to a beam guiding element made of glass having a quality factor F(RGB)=F(436 nm)+F(546 nm)+F(644 nm)=S(436 nm)×(Ext0(436 nm)+Ext1(436 nm)) / k+S(546 nm)×(Ext0(546 nm)+Ext1(546 nm)) / k+S(644 nm)×(Ext0(644 nm)+Ext1(644 nm)) / k and F(RGB)<40 ppm / W. The invention also relates to a beam guiding element made of glass having an induced absorbance Ext1(436 nm)<0.01 / cm. The invention also relates to a beam-guiding element made of glass having an induced absorbance Ext1(RGB)=Ext1(436 nm)+Ext1(546 nm)+Ext1(644 nm), where Ext1(RGB)<0.03 / cm.

[0164] The present invention also has the following properties: Quality factor F(436nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k, where F(436nm) < 15 ppm / W, Quality factor F(RGB) = F(436nm) + F(546nm) + F(644nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k + S(546nm) × (Ext0(546nm) + Ext1(546nm)) / k + S(644nm) × (Ext0(644nm) + Ext1(644nm)) / k, where F(RGB)<40ppm / W, Induced absorbance Ext1 (436 nm) < 0.01 / cm, Induced absorbance Ext1(RGB) = Ext1(436nm) + Ext1(546nm) + Ext1(644nm), where Ext1(RGB)<0.03 / cm; The present invention also relates to a beam-guiding element made of glass having one or more of these properties, for example at least two or at least three of these properties.

[0165] The present invention also has the following properties: Quality factor F(436nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k, where F(436nm) < 15 ppm / W, Quality factor F(RGB) = F(436nm) + F(546nm) + F(644nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k + S(546nm) × (Ext0(546nm) + Ext1(546nm)) / k + S(644nm) × (Ext0(644nm) + Ext1(644nm)) / k, where F(RGB)<40ppm / W, Induced absorbance Ext1 (436 nm) < 0.01 / cm, The present invention relates to a beam guiding element made of glass having one or more of these properties, for example at least two of these properties.

[0166] The present invention also has the following properties: Quality factor F(436nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k, where F(436nm) < 15 ppm / W, Induced absorbance Ext1 (436 nm) < 0.01 / cm, The present invention relates to a beam guiding element made of glass having one or more of the following:

[0167] Preferably, the beam guiding element is a lens, a light guiding rod, a prism, a freeform or aspherical surface, particularly preferably a prism.

[0168] The present invention also relates to glasses having a quality factor according to the invention and / or an induced absorbance Ext1 according to the invention. In particular, the present invention relates to glasses having a quality factor F(436 nm) = S(436 nm) x (Ext0(436 nm) + Ext1(436 nm)) / k, where F(436 nm) < 15 ppm / W. The present invention also relates to glasses having a quality factor F(RGB) = F(436 nm) + F(546 nm) + F(644 nm) = S(436 nm) x (Ext0(436 nm) + Ext1(436 nm)) / k + S(546 nm) x (Ext0(546 nm) + Ext1(546 nm)) / k + S(644 nm) x (Ext0(644 nm) + Ext1(644 nm)) / k, where F(RGB) < 40 ppm / W. The present invention also relates to glasses having an induced absorbance Ext1(436 nm), where Ext1(436 nm)<0.01 / cm. The present invention also relates to glasses having an induced absorbance Ext1(RGB)=Ext1(436 nm)+Ext1(546 nm)+Ext1(644 nm), where Ext1(RGB)<0.03 / cm.

[0169] The present invention also has the following properties: Quality factor F(436nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k, where F(436nm) < 15 ppm / W, Quality factor F(RGB) = F(436nm) + F(546nm) + F(644nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k + S(546nm) × (Ext0(546nm) + Ext1(546nm)) / k + S(644nm) × (Ext0(644nm) + Ext1(644nm)) / k, where F(RGB)<40ppm / W, Induced absorbance Ext1 (436 nm) < 0.01 / cm, Induced absorbance Ext1(RGB) = Ext1(436nm) + Ext1(546nm) + Ext1(644nm), where Ext1(RGB)<0.03 / cm; The present invention also relates to glasses having one or more of these properties, such as at least two or at least three of these properties.

[0170] The present invention also has the following properties: Quality factor F(436nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k, where F(436nm) < 15 ppm / W, Quality factor F(RGB) = F(436nm) + F(546nm) + F(644nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k + S(546nm) × (Ext0(546nm) + Ext1(546nm)) / k + S(644nm) × (Ext0(644nm) + Ext1(644nm)) / k, where F(RGB)<40ppm / W, Induced absorbance Ext1 (436 nm) < 0.01 / cm, The present invention also relates to glasses having one or more of these properties, for example at least two of these properties.

[0171] The present invention also has the following properties: Quality factor F(436nm) = S(436nm) × (Ext0(436nm) + Ext1(436nm)) / k, where F(436nm) < 15 ppm / W, Induced absorbance Ext1 (436 nm) < 0.01 / cm, The present invention also relates to a glass having one or more of the following:

[0172] The invention also relates to the use of the imaging system, the beam guiding element and / or the glass according to the invention, in particular in a projector or in material processing.

[0173] The invention also relates to projectors, in particular DLP projectors, comprising the imaging system, beam guiding elements and / or glass of the invention. [Brief explanation of the drawings]

[0174] [Figure 1] 1 is a schematic diagram of an embodiment of the present invention. An exemplary configuration of the imaging system as a DLP projector is shown. Three colors (arrows 5) generated by laser light source 1, blue, green, and red, leave laser light source 1 and reach beam guiding element 2. Beam guiding element 2 deflects the light toward image generation chip 3 (arrow 6). Images generated by image generation chip 3 (specifically, one image each of blue, green, and red) then reach beam guiding element 2, as indicated by arrows 7. Beam guiding element 2 controls the color composite image to reach projection optics 4, as indicated by arrow 8. [Figure 2] 1 is a bar graph showing the quality factor F(436 nm) and the quality factor F(RGB) for Examples 1 to 8 of the present invention and Comparative Example A, which is not of the present invention. The values shown on the y-axis are expressed in "ppm / W." [Figure 3] 1 is a bar graph showing induced absorbance Ext1 (436 nm) and Ext1 (RGB) for Examples 1 to 8 of the present invention and Comparative Example A, which is not of the present invention. The values shown on the y-axis are expressed in "1 / cm".

[0175] Example In Examples 1 to 8 of the present invention and Comparative Example A, exemplary glass samples having a sample thickness of 100 mm were irradiated with laser light having a wavelength of 455 nm at 345 W / cm. 2The samples were irradiated for 72 hours at a power density of 1000 psig (1000 psig). To achieve both a high power density and uniform irradiation of the samples, the samples were polished on all sides and measured in 4 × 4 mm diameter. 2 The laser beam was irradiated at an angle of total internal reflection (TIR) on the incident surface of the sample with a size of 345 W / cm using a 55 W laser. 2 The power density in the volume was approximately 331 W / cm. 2 It was.

[0176] The sample size was 100 mm x 4 mm x 4 mm.

[0177] The glass composition is shown in Table 1 below (% by weight).

[0178] [Table 6]

[0179] These glasses differed with respect to their MnO content as follows: In Example 2, the MnO content was 0.7 ppm (by weight); In Comparative Example A, the MnO content was 1.1 ppm (by weight); and for the remaining Exemplary Glass 1 and Glasses 3-8, the MnO content was each 0.1 ppm (by weight).

[0180] The quality factors F(436 nm), F(546 nm), F(644 nm) and F(RGB) were calculated according to the above formula. For this purpose, the corresponding values of the degree of heating S, the uninduced absorbance Ext0 and the induced absorbance Ext1, as well as the thermal conductivity k of the glass for wavelengths of 436 nm, 546 nm and 644 nm were determined. The results are shown in Figures 2 and 3. The measured and calculated values are summarized in Table 2 below.

[0181] [Table 7]

[0182] It can be seen that inventive glasses 1 to 8 have quality factors F(436 nm)<15 ppm / W, F(546 nm)<12 ppm / W, F(644 nm)<10 ppm / W, and F(RGB)<40 ppm / W, in contrast to comparative example A. Furthermore, inventive glasses 1 to 8 have induced absorbances Ext1 of Ext1(436 nm)<0.01 / cm, Ext1(546 nm)<0.01 / cm, Ext1(644 nm)<0.009 / cm, and Ext1(RGB)<0.03 / cm, in contrast to comparative example A.

[0183] Examples 1-7 and Comparative Example A have very similar compositions. Each is a borosilicate glass. The main difference is that Examples 1, 5, and 7, as well as Comparative Example A, are refined using SbO, while Examples 2, 3, 4, and 6 are refined using Sn / Cl. Comparative Example A was produced using conventional raw materials, resulting in a relatively high MnO content of over 1.0 ppm. Examples 2, 3, 5, and 7 used CeO. Examples 1, 4, and 7, as well as Comparative Example A, further contained a small amount of TiO. Example 8 is a silicate glass refined using SnO.

[0184] Particularly good results were obtained with Example 6, which is characterized by Sn / Cl purification and the absence of TiO2. [Explanation of symbols]

[0185] 1 laser light source 2 beam guide elements 3. Image generation chip 4 Projection optical system 5 Light reaching the beam guide element from the laser source 6. Light is deflected from the beam guide element towards the image generating chip 7 The image generated by the imaging chip reaches the beam guide element The 8-color composite image reaches the projection optics.

Claims

1. 1. An imaging system, comprising: a) wavelength λ in the spectral range of 380 nm to 490 nm Ｂ At least one laser light source B having b) a beam guiding element; Equipped with The laser source B has an output of 10 W / cm at at least one point of the beam guiding element. ２ Suitable for generating average surface power densities of The beam guide element is configured to １ (436 nm), and Ext １ (436 nm) < 0.01 / cm; the glass comprises Nb 2 O 5 in a proportion of 0 to 50% by weight and TiO 2 in a proportion of 0 to 0.3% by weight, The following conditions, namely (i) less than 1.0 ppm (by weight) of MnO 2 content; (ii) at least 0.1 wt. % of an SnO 2 component and at least 0.05 wt. % of a Cl component; (iii) at least 0.005 wt. % and at most 0.05 wt. % of a CeO 2 component; At least one of the following is satisfied: Imaging system.

2. 1. An imaging system, comprising: a) wavelength λ in the spectral range of 380 nm to 490 nm Ｂ At least one laser light source B having b) a beam guiding element; Equipped with The laser source B has an output of 10 W / cm at at least one point of the beam guiding element. ２ Suitable for generating average surface power densities of The beam guiding element has a quality factor F(436 nm)=S(436 nm)×(Ext ０ (436nm)+Ext １ (436 nm)) / k, where S(436 nm) is the heating degree at a wavelength of 436 nm, and Ext １ (436 nm) is obtained by irradiating a 100 mm thick sample with a 455 nm laser beam for 72 hours at 345 W / cm ２ After irradiation with a power density of ０ is the absorbance at a wavelength of 436 nm added relative to (436 nm), and Ext ０ (436 nm) is the absorbance at a wavelength of 436 nm in the absence of corresponding illumination in a 100 mm thick sample, k is the thermal conductivity, and F(436 nm)<15 ppm / W; the glass comprises Nb 2 O 5 in a proportion of 0 to 50% by weight and TiO 2 in a proportion of 0 to 0.3% by weight, The following conditions, namely (i) less than 1.0 ppm (by weight) of MnO 2 content; (ii) at least 0.1 wt. % of an SnO 2 component and at least 0.05 wt. % of a Cl component; (iii) at least 0.005 wt. % and at most 0.05 wt. % of a CeO 2 component; an imaging system in which at least one of the following is satisfied.

3. 1. An imaging system, comprising: a) wavelength λ in the spectral range of 380 nm to 490 nm Ｂ and at least one laser light source B having a wavelength λ in the spectral range from greater than 490 nm to 585 nm. Ｇ and at least one laser light source G having a wavelength λ in the spectral range from greater than 585 nm to 750 nm. Ｒ At least one laser light source R having b) a beam guiding element; Equipped with The laser source B, the laser source G and the laser source R have an output of 10 W / cm at least at one point of the beam guiding element. ２ Suitable for generating average surface power densities of The beam guide element is configured to １ (RGB)=Ext １ (436nm)+Ext １ (546nm)+Ext １ (644 nm), and Ext １ (RGB)<0.03 / cm; the glass comprises Nb 2 O 5 in a proportion of 0 to 50% by weight and TiO 2 in a proportion of 0 to 0.3% by weight, The following conditions, namely (i) less than 1.0 ppm (by weight) of MnO 2 content; (ii) at least 0.1 wt. % of an SnO 2 component and at least 0.05 wt. % of a Cl component; (iii) at least 0.005 wt. % and at most 0.05 wt. % of a CeO 2 component; At least one of the following is satisfied: Imaging system.

4. 1. An imaging system, comprising: a) wavelength λ in the spectral range of 380 nm to 490 nm Ｂ and at least one laser light source B having a wavelength λ in the spectral range from greater than 490 nm to 585 nm. Ｇ and at least one laser light source G having a wavelength λ in the spectral range from greater than 585 nm to 750 nm. Ｒ At least one laser light source R having b) a beam guiding element; Equipped with The laser source B, the laser source G and the laser source R have an output of 10 W / cm at least at one point of the beam guiding element. ２ Suitable for generating average surface power densities of The beam guiding element has a quality factor F(RGB)=F(436 nm)+F(546 nm)+F(644 nm)=S(436 nm)×(Ext ０ (436nm)+Ext １ (436nm)) / k+S(546nm)×(Ext ０ (546nm)+Ext １ (546nm)) / k+S(644nm)×(Ext ０ (644nm)+Ext １ (644 nm)) / k and F(RGB)<40 ppm / W, where k is thermal conductivity; the glass comprises Nb 2 O 5 in a proportion of 0 to 50% by weight and TiO 2 in a proportion of 0 to 0.3% by weight, The following conditions, namely (i) less than 1.0 ppm (by weight) of MnO 2 content; (ii) at least 0.1 wt. % of an SnO 2 component and at least 0.05 wt. % of a Cl component; (iii) at least 0.005 wt. % and at most 0.05 wt. % of a CeO 2 component; At least one of the following is satisfied: Imaging system.

5. The laser light source is a diode laser. The imaging system according to any one of claims 1 to 4.

6. the beam guiding element is a prism; The imaging system according to any one of claims 1 to 5.

7. The laser light source has an output of 20 W / cm at at least one point of the beam guiding element. ２ ~300 W / cm ２ suitable for generating an average surface power density of The imaging system according to any one of claims 1 to 6.

8. S (436 nm), S (546 nm) and S (644 nm) are up to 50 ppm / K; The imaging system according to any one of claims 1 to 7.

9. Ext ０ (436nm), Ext. ０ (546 nm) and Ext ０ (644 nm) is less than 0.01 / cm; The imaging system according to any one of claims 1 to 8.

10. Ext １ (436nm), Ext. １ (546 nm) and Ext １ (644 nm) is less than 0.009 / cm; The imaging system according to any one of claims 1 to 9.

11. The thermal conductivity k is greater than 0.005 W / (cm K); 5. The imaging system according to claim 2 or 4.

12. The average dn / dT at a wavelength of 436 nm, a wavelength of 546 nm, and / or a wavelength of 644 nm in a temperature range of 20°C to 40°C is in a range of 0.1 ppm / K to 8.0 ppm / K. The imaging system according to any one of claims 1 to 11.

13. A beam guiding element, said beam guiding element having the following properties: Quality factor F(436 nm) = S(436 nm) × (Ext ０ (436nm)+Ext １ (436nm)) / k, F(436nm)<15ppm / W, ・Quality factor F(RGB) = F(436 nm) + F(546 nm) + F(644 nm) = S(436 nm) × (Ext ０ (436 nm) + Ext １ (436 nm)) / k + S(546 nm) × (Ext ０ (546 nm) + Ext １ (546 nm)) / k + S(644 nm) × (Ext ０ (644 nm) + Ext １ (644 nm)) / k, F(RGB) < 40 ppm / W, Induced absorbance Ext １ (436nm)<0.01 / cm, Induced absorbance Ext １ (RGB)=Ext １ (436nm)+Ext １ (546nm)+Ext １ (644 nm), where Ext １ (RGB)<0.03 / cm, wherein k is the thermal conductivity; the glass comprises Nb 2 O 5 in a proportion of 0 to 50% by weight and TiO 2 in a proportion of 0 to 0.3% by weight, The following conditions, namely (i) less than 1.0 ppm (by weight) of MnO 2 content; (ii) at least 0.1 wt. % of an SnO 2 component and at least 0.05 wt. % of a Cl component; (iii) at least 0.005 wt. % and at most 0.05 wt. % of a CeO 2 component; At least one of the following is satisfied: Beam guiding elements.

14. A beam guiding element, The beam guiding element has a quality factor F(436 nm)=S(436 nm)×(Ext ０ (436nm)+Ext １ (436 nm)) / k and F(436 nm)<15 ppm / W; the glass comprises Nb 2 O 5 in a proportion of 0 to 50% by weight and TiO 2 in a proportion of 0 to 0.3% by weight, The following conditions, namely (i) less than 1.0 ppm (by weight) of MnO 2 content; (ii) at least 0.1 wt. % of an SnO 2 component and at least 0.05 wt. % of a Cl component; (iii) at least 0.005 wt. % and at most 0.05 wt. % of a CeO 2 component; A beam guiding element, wherein at least one of the following is satisfied:

15. the beam guiding element is selected from a lens, a prism, an aspheric surface, a flat plate, a freeform, a fast axis collimator and / or a light guiding rod; A beam guiding element according to any one of claims 13 and 14.

16. A glass, said glass having the following properties: Quality factor F(436 nm) = S(436 nm) × (Ext ０ (436nm)+Ext １ (436nm)) / k, F(436nm)<15ppm / W, ・Quality coefficient F(RGB) = F(436 nm) + F(546 nm) + F(644 nm) = S(436 nm) × (Ext ０ (436 nm) + Ext １ (436 nm)) / k + S(546 nm) × (Ext ０ (546 nm) + Ext １ (546 nm)) / k + S(644 nm) × (Ext ０ (644 nm) + Ext １ (644 nm)) / k, F(RGB) < 40 ppm / W, Induced absorbance Ext １ (436nm)<0.01 / cm, Induced absorbance Ext １ (RGB)=Ext １ (436nm)+Ext １ (546nm)+Ext １ (644 nm), where Ext １ (RGB)<0.03 / cm, where k is the thermal conductivity; the glass comprises Nb 2 O 5 in a proportion of 0 to 50% by weight and TiO 2 in a proportion of 0 to 0.3% by weight, The following conditions, namely (i) less than 1.0 ppm (by weight) of MnO 2 content; (ii) at least 0.1 wt. % of an SnO 2 component and at least 0.05 wt. % of a Cl component; (iii) at least 0.005 wt. % and at most 0.05 wt. % of a CeO 2 component; At least one of the following is satisfied: Glass.

17. It is glass, The glass has a quality factor F(436 nm)=S(436 nm)×(Ext ０ (436nm)+Ext １ (436 nm)) / k, where F(436 nm)<15 ppm / W, and k is the thermal conductivity; the glass comprises Nb 2 O 5 in a proportion of 0 to 50% by weight and TiO 2 in a proportion of 0 to 0.3% by weight, The following conditions, namely (i) less than 1.0 ppm (by weight) of MnO 2 content; (ii) at least 0.1 wt. % of an SnO 2 component and at least 0.05 wt. % of a Cl component; (iii) at least 0.005 wt. % and at most 0.05 wt. % of a CeO 2 component; At least one of the following is satisfied: Glass.

18. Use of an imaging system according to any one of claims 1 to 12 in a projector or in material processing.

19. A projector comprising an imaging system according to any one of claims 1 to 12.

20. The glass comprising the following components in the stated weight percents: 【Table 1】 The imaging system according to any one of claims 1 to 12.

21. The glass contains SiO 2 in a proportion of 30% to 80% by weight, or in a proportion of 43% to 80% by weight. The imaging system according to any one of claims 1 to 12.

22. The glass comprising the following components in the stated weight percents: 【Table 2】 16. The beam guiding element according to any one of claims 13 to 15.

23. The glass contains SiO 2 in a proportion of 30% to 80% by weight, or in a proportion of 43% to 80% by weight.

16. The beam guiding element according to any one of claims 13 to 15.

24. The glass comprising the following components in the stated weight percents: 【Table 3】 18. The glass of claim 16 or 17.

25. The glass contains SiO 2 in a proportion of 30% to 80% by weight, or in a proportion of 43% to 80% by weight.

18. The glass of claim 16 or 17.

Images