Optical filters
An optical filter may include a monolithic substrate. The optical filter may include a first component filter disposed onto a first region of the monolithic substrate. The first component filter may be a near infrared (NIR) bandpass filter. The optical filter may include a second component filter disposed onto a second region of the monolithic substrate. The second component filter may include a red-green-blue (RGB) bandpass filter. A separation between the first component filter and the second component filter may be less than approximately 50 micrometers (μm).
1. An optical filter, comprising:
a monolithic substrate;
a first component filter integrated onto a first region of the monolithic substrate,
the first component filter comprising a near infrared (NIR) bandpass filter, and
the first component filter being associated with a spectral range from approximately 700 nm to approximately 1100 nm; and
a second component filter integrated onto a second region of the monolithic substrate,
the second component filter comprising a red-green-blue (RGB) bandpass filter, and
a separation between the first component filter and the second component filter being less than approximately 50 micrometers (μm).
2. The optical filter of claim 1 , further comprising:
an absorber disposed at a transition zone of the optical filter,
the transition zone being at an edge of the first component filter and the second component filter.
3. The optical filter of claim 2 , where the first component filter and the second component filter are disposed between the absorber and the monolithic substrate.
4. The optical filter of claim 2 , where the absorber is disposed between the first component filter and the second component filter.
5. The optical filter of claim 2 , where the absorber is disposed between the first component filter and the monolithic substrate and between the second component filter and the monolithic substrate.
6. The optical filter of claim 1 , further comprising:
an anti-reflectance coating disposed onto a surface of the monolithic substrate, such that the monolithic substrate is disposed between the anti-reflectance coating and the first component filter and between the anti-reflectance coating and the second component filter.
7. The optical filter of claim 1 , where the monolithic substrate is a glass substrate or a silica substrate.
8. The optical filter of claim 1 , where the first component filter and the second component filter are disposed onto the monolithic substrate using a sputter deposition procedure.
9. The optical filter of claim 1 , where the first component filter and the second component filter are disposed onto the monolithic substrate using a photolithography procedure.
10. The optical filter of claim 1 , where the first component filter is associated with a first spectral range and the second component filter is associated with a second, different spectral range.
11. The optical filter of claim 1 , where the second component filter is associated with a spectral range of from approximately 400 nm to approximately 700 nm.
12. The optical filter of claim 1 , where the second component filter is associated with a spectral range of from approximately 420 nm to approximately 630 nm.
13. The optical filter of claim 1 , where the separation between the first component filter and the second component filter is less than approximately 30 μm.
14. The optical filter of claim 1 ,
wherein the first component filter includes one or more first filter layers,
wherein the second component filter includes one or more second filter layers, and
wherein a first thickness associated with at least one layer of the one or more first filter layers is different from a second thickness associated with at least one layer of the one or more second filter layers.
15. An optical system, comprising:
an optical filter including a plurality of component filters configured to filter an input optical signal and provide a filtered input optical signal,
the plurality of component filters being associated with two or more spectral ranges,
the plurality of component filters including:
a first component filter that includes a first set of filter layers and a second set of filter layers, and
a second component filter that includes a third set of filter layers and a fourth set of filter layers, and
a first thickness associated with at least one layer of the first set of filter layers or the second set of filter layers is different from a second thickness associated with at least one layer of the third set of filter layers or the fourth set of filter layers; and
an optical sensor configured to receive the filtered input optical signal and provide an output electrical signal.
16. The optical system of claim 15 , where the filtered input optical signal includes two or more component filtered input optical signals corresponding to the two or more spectral ranges.
17. The optical system of claim 15 , where the output electrical signal is related to performing at least one of:
an iris detection functionality,
an iris recognition functionality, or
an low-light security photography functionality.
18. A bandpass filter, comprising:
a first patterned component filter, comprising:
a first set of filter layers associated with a first refractive index and deposited using a sputter deposition technique, and
a second set of filter layers associated with a second refractive index that is less than the first refractive index and deposited using the sputter deposition technique; and a second patterned component filter, comprising:
a third set of filter layers associated with a third refractive index and deposited using the sputter deposition technique, and
a fourth set of filter layers associated with a fourth refractive index and deposited using the sputter deposition technique,
where the first patterned component filter is separated from the second patterned component filter by less than approximately 30 micrometers (μm),
where the second patterned component filter comprises a red-green-blue (RGB) bandpass filter,
where the first patterned component filter is associated with a first bandpass and the second patterned component filter is associated with a second bandpass that is different from the first bandpass, and
where a first thickness associated with at least one of the first set of filter layers or the second set of filter layers is different from a second thickness associated with at least one of the third set of filter layers or the fourth set of filter layers.
19. The bandpass filter of claim 18 , where at least one filter layer of the first set of filter layers, the second set of filter layers, the third set of filter layers, or the fourth set of filter layers is one of:
a silicon based material,
a hydrogenated silicon based material,
a germanium based material,
a hydrogenated germanium based material,
a silicon dioxide (SiO 2 ) material,
an aluminum oxide (Al 2 O 3 ) material,
a titanium dioxide (TiO 2 ) material,
a niobium pentoxide (Nb 2 O 5 ) material,
a tantalum pentoxide (Ta 2 O 5 ) material, or
a magnesium fluoride (MgF 2 ) material.
20. The bandpass filter of claim 18 , where at least one filter layer of the first set of filter layers, the second set of filter layers, the third set of filter layers, or the fourth set of filter layers is annealed.