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US 2021/0231847 A1Published application
Band-pass near-infrared (nir) filter, method of production of a band-pass nir filter and uses thereof
AssigneeSCHOTT Glass Technologies (Suzhou) Co. Ltd.
InventorsWei XIAO, Yigang LI, Guangjun ZHANG
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Abstract
The present disclosure relates to a band-pass near-infrared (NIR) filter and to a method of production of a band-pass NIR filter. The disclosure further relates to the use of such band-pass NIR filter, in particular in an infrared sensor, such as for object recognition, in particular facial recognition.
Claims21
A method of producing a band-pass near-infrared (NIR) filter, the method comprising the following steps:
- a) providing a glass substrate having a length L0,GL at a temperature T0 and having a scale factor I that is smaller than 1500 kPa/K, wherein I is defined by the equation
- I
- =
- E
- 1
- -
- υ
- ·
- α
- ,
- wherein E is the Young's modulus of the glass substrate, ν is the Poisson's ratio of the glass substrate, and α is the coefficient of thermal expansion (CTE) of the glass substrate in the range of 20° C. to 300° C.,
- b) depositing a band-pass NIR coating comprising alternating layers of high refractive index material and low refractive index material on at least one side of the glass substrate to form a coated glass substrate, so that the high refractive index material is in direct contact with the glass substrate and has a length LCT,HRF, wherein the glass substrate reaches a maximum temperature TCT and a maximum length LCT,GL during deposition of the coating,
- c) letting the coated glass substrate cool to the temperature T0, wherein T0 is lower than 30° C., and wherein the glass has a length L0,GL−LTS,GL when reaching T0, and wherein LTS,GL accounts for length reduction due to a decrease of fictive temperature,
- wherein the coated glass substrate has the properties:
- that the glass has a length LOT,GL−LTS,GL when being heated to an operating temperature TOT subsequent to step c) with T0<TOT<TCT, and
- that the high refractive index material being in direct contact with the glass substrate has a length LOT,HRF at temperature TOT, wherein the difference
- L
- OT
- ,
- HRF
- L
- CT
- ,
- HRF
- -
- L
- O
-
- T
- ,
- G
-
- L
- -
- L
- T
-
- S
- ,
- G
-
- L
- L
- C
-
- T
- ,
- G
-
- L
- is smaller than 0.05.
48 more elements
A band-pass near-infrared (NIR) filter comprising:
- a glass substrate;
- and
- at least one coating,
- wherein the glass substrate has a scale factor I that is smaller than 1500 kPa/K, wherein I is defined by the equation
- I
- =
- E
- 1
- -
- υ
- ·
- α
- ,
- wherein E is the Young's modulus of the glass substrate, ν is the Poisson's ratio of the glass substrate, and α is the coefficient of thermal expansion (CTE) of the glass substrate in the range of 20° C. to 300° C., and
- wherein the maximum internal stress of the glass substrate at operating temperature TOT is smaller than 300 MPa.
12 more elements
Dependencies are inferred from the claim text.