Search

CN-121995552-A - Imaging system comprising a light beam guiding element with high sun resistance

CN121995552ACN 121995552 ACN121995552 ACN 121995552ACN-121995552-A

Abstract

The invention relates to an imaging system comprising at least one laser light source having a wavelength in the visible spectral range and a beam guiding element having a high resistance to insolation at a high beam power density. The invention also relates to the use of the imaging system, in particular in projectors and material processing.

Inventors

  • R Da Da Ke
  • P. NASS
  • S. Roy Kerr
  • V - haagman
  • U. Pechold

Assignees

  • 肖特股份有限公司

Dates

Publication Date
20260508
Application Date
20210524
Priority Date
20200528

Claims (13)

  1. 1. A glass having a quality factor F (436 nm) =s (436 nm) (Ext 0 (436nm)+Ext 1 (436 nm))/k, wherein S (436 nm) is the heat at a wavelength of 436nm, ext 1 (436 nm) is the further absorbance at a wavelength of 436nm after 15 hours of irradiation of a sample having a thickness of 10mm with a HOK 4 lamp compared to Ext 0 (436 nm), ext 0 (436 nm) is the absorbance at a wavelength of 436nm of a sample having no thickness of 10mm irradiated with a HOK 4 lamp, wherein F (436 nm) <700ppm/W, and the glass comprises the following components (wt%): 。
  2. 2. the glass of claim 1, wherein the glass is a borosilicate glass comprising the following composition (in weight%): 。
  3. 3. the glass of claim 1, wherein the glass is a silicate glass comprising the following components (in weight%): 。
  4. 4. the glass of claim 1, wherein the glass is a fluorophosphate glass comprising the following ingredients (in weight%): 。
  5. 5. a beam guiding element consisting of a glass according to any one of claims 1 to 4.
  6. 6. The light beam directing element of claim 5, wherein the light beam directing element is a prism.
  7. 7. An imaging system comprising the beam directing element of claim 5 or 6 and at least one laser light source selected from the group consisting of a laser light source B having a wavelength lambda B in the spectral range of 380nm to 490nm, a laser light source G having a wavelength lambda G in the spectral range of >490nm to 585nm, and a laser light source R having a wavelength lambda R in the spectral range of >585nm to 750nm, Wherein the laser light source is adapted to produce an average surface power density of greater than 10W/cm 2 in at least one point of the beam directing element, and the beam directing element consists of a glass having a quality factor F (436 nm) =s (436 nm) × (Ext 0 (436nm)+Ext 1 (436 nm))/k, wherein S (436 nm) is the heat at wavelength 436nm, ext 1 (436 nm) is the further absorbance at 436nm wavelength after irradiating a sample having a thickness of 10mm with a HOK 4 lamp for 15 hours compared to Ext 0 (436 nm), ext 0 (436 nm) is the absorbance at 436nm wavelength without irradiating a sample having a thickness of 10mm with a HOK 4 lamp, k is the thermal conductivity, and wherein F (436 nm) <700 ppm/W.
  8. 8. The imaging system of claim 7, comprising a laser light source B having a wavelength λ B in a spectral range of 380nm to 490nm, a laser light source G having a wavelength λ G in a spectral range of >490nm to 585nm, and a laser light source R having a wavelength λ R in a spectral range of >585nm to 750nm, wherein the laser light source B, the laser light source G, and the laser light source R are adapted to produce an average surface power density of greater than 10W/cm 2 in at least one point of the beam directing element, and the beam directing element consists of glass having a quality factor F(RGB)=F(436nm)+F(546nm)+F(644nm)=S(436nm)*(Ext 0 (436nm)+Ext 1 (436nm))/k+S(546nm)*(Ext 0 (546nm)+Ext 1 (546nm))/k+S(644nm)*(Ext 0 (644nm)+Ext 1 (644nm))/k, wherein F (RGB) <1000 ppm/W, or wherein F (RGB) is at most 800ppm/W.
  9. 9. The imaging system of claim 7, wherein the laser light source is a diode laser.
  10. 10. The imaging system of claim 7, wherein the laser light source is adapted to produce an average surface power density of 15 to 60W/cm 2 in at least one point of the beam directing element.
  11. 11. The imaging system of claim 7, wherein S (436 nm), S (546 nm), and S (644 nm) are at most 50ppm/K, or Wherein Ext 0 (436nm)、Ext 0 (546 nm) and Ext 0 (644 nm) are less than 0.01/cm, or Wherein Ext 0 (436nm)、Ext 0 (546 nm) and Ext 0 (644 nm) are less than 0.3/cm, or Wherein the thermal conductivity K is higher than 0.005W/(cm K).
  12. 12. The imaging system of claim 7, wherein an average dn/dT at a temperature range of 20 to 40 ℃ at 436nm, 546nm, and/or 644nm wavelength is in a range of 0.1 to 8.0ppm/K, wherein dn/dT represents a change in refractive index with temperature.
  13. 13. A projector comprising an imaging system according to any one of claims 7 to 12.

Description

Imaging system comprising a light beam guiding element with high sun resistance The present application is a divisional application of patent application 202110564050.2, titled "imaging system comprising a beam guiding element with high sun resistance", filed on the date 2021, 5, 24. Technical Field The invention relates to an imaging system comprising at least one laser light source having a wavelength in the visible spectral range and a beam guiding element having a high resistance to insolation at a high beam power density. The invention also relates to the use of the imaging system, in particular in projectors and material processing. Background Currently, light sources for projectors are undergoing a change from xenon to light-emitting laser substances and pure RGB laser light sources, with increasing luminous flux and power density. Current motion picture projectors with laser light sources achieve luminous fluxes of, for example, up to 75000 lumens and surface power densities of up to 50W/cm 2 or higher. As luminous flux and power density increase, the thermal load of the optical assembly increases, thereby compromising the quality and long-term stability of the projection. The optical system of a cinematic projector is usually composed of a large-volume arrangement of prisms and projection objectives. In particular, the arrangement of prisms is subject to high thermal loads. Thus, there is an increasing demand for optical glasses with respect to low absorption losses, i.e. a tendency towards maximum transmittance and low insolation, i.e. low induced absorption losses in applications. Conventional xenon-based cinema projectors have a maximum luminous flux of up to 45000 lumens. However, in the latest laser-based projectors, luminous fluxes of up to 75000 lumens and surface power densities of up to 50W/cm 2 or higher are achieved. The intense blue laser excites the emission of yellow light in the converter. Green and yellow channels are extracted from the yellow light by means of a dichroic filter. A portion of the blue light is used for the blue channel. All three channels are then used for projection. Projection systems typically consist of a complex arrangement of prisms that are used to direct a single color channel to a DLP chip and mix the signals to generate an image. The optical path length may be greater than 100 to 200mm. Any light absorption within the prism arrangement results in a temperature gradient and thermal lens effects. Therefore, the prism glass should have as high transmittance as possible in the visible wavelength range. An additional effect that becomes more and more important as the luminous flux of the projector increases is the sun exposure effect in glass. The creation of defect centers induced by the absorption of the prism glass may lead to a decrease in transmittance, which in turn co-exists with the thermal lens effect. However, this sun effect is not only relevant to the latest projector optical systems. This phenomenon plays an increasingly important role also in material handling applications. Disclosure of Invention It is therefore an object of the present invention to provide an imaging system with a beam guiding element, which is characterized by a high resistance to insolation in the visible spectral range, in particular in the blue spectral range, and which can therefore be used not only excellently in projectors, but also in material processing applications. The imaging system is in particular a system with at least one light source and at least one beam guiding element, in particular a lens, a prism, an aspherical mirror and/or a light guiding rod. Such light-guiding rods use total reflection at interface glass/air and typically their length does not exceed 300mm. Such imaging systems are used, for example, in projectors, especially film projectors. In this case, an image is generated (guided by the target beam of light of the light source) on the screen, for example, using an imaging system, the image being identifiable to the observer. In general, the highest power densities occur in prisms, in particular prisms responsible for color channel mixing. It is therefore particularly important to provide such prism-beam directing elements which are made of materials capable of withstanding these power densities without the associated sun effects. Imaging systems are also used in material processing. By means of the target beam guidance, the light of the light source can be focused onto the material to be processed, so that the energy input of the light radiation can be used for material processing. This object is achieved by the subject matter of the claims. This object is achieved in particular by an imaging system comprising: a) At least one laser light source selected from the group consisting of a laser light source B having a wavelength lambda B in a spectral range of 380nm to 490nm, a laser light source G having a wavelength lambda G in a spectral range of >