Optical devices
An optical device is provided. The optical device includes a time-of-flight (TOF) sensor array, a photon conversion thin film, and a light source. The photon conversion thin film is disposed above the time-of-flight sensor array. The light source emits light with a first wavelength towards the photon conversion thin film to be converted into light with a second wavelength received by the time-of-flight sensor array. The second wavelength is longer than the first wavelength.
1. An optical device, comprising:
a time-of-flight (TOF) sensor array;
a photon conversion thin film disposed above the time-of-flight sensor array;
a light source which emits light with a first wavelength towards the photon conversion thin film to be converted into light with a second wavelength received by the time-of-flight sensor array, wherein the second wavelength is longer than the first wavelength; and
an optical component group disposed on the time-of-flight sensor array, wherein the optical component group comprises a pinhole-type collimator and a filter, and the filter comprises a longpass (LP) filter or a narrow bandpass (NBP) filter.
2. The optical device as claimed in claim 1 , wherein the time-of-flight sensor array comprises a silicon time-of-flight sensor, a germanium (Ge) time-of-flight sensor, an indium gallium arsenide (InGaAs) time-of-flight sensor, an organic photodiode (OPD) time-of-flight sensor or a perovskite time-of-flight sensor.
3. The optical device as claimed in claim 1 , further comprising a plurality of microlenses disposed on the optical component group.
4. The optical device as claimed in claim 1 , wherein the photon conversion thin film comprises organic materials, inorganic materials or organic-inorganic-hybrid materials forming a zero-dimensional, a one-dimensional, a two-dimensional or a bulk structure, wherein the photon conversion thin film absorbs short-wavelength photons and emits long-wavelength photons, and has a temperature-dependent photoluminescence lifetime.
5. The optical device as claimed in claim 1 , wherein the photon conversion thin film is pixelated with different color conversion materials or with a same color conversion material, and when the photon conversion thin film is pixelated with the same color conversion material, there is an air gap between the adjacent pixelated photon conversion thin film.
6. The optical device as claimed in claim 1 , wherein the light source is disposed adjacent to the time-of-flight sensor array.
7. The optical device as claimed in claim 1 , wherein the light source is disposed between the time-of-flight sensor array and the photon conversion thin film.
8. The optical device as claimed in claim 7 , further comprising a waveguide connected to the light source.
9. The optical device as claimed in claim 7 , further comprising a light guide plate (LGP) connected to the light source.
10. The optical device as claimed in claim 1 , further comprising a diffuser disposed on the light source, wherein the light source is disposed in the time-of-flight sensor array.
11. The optical device as claimed in claim 7 , wherein the light source comprises a semi-transparent organic light-emitting diode (OLED) or a semi-transparent Perovskite light-emitting diode.
12. The optical device as claimed in claim 1 , further comprising a longpass filter disposed on the photon conversion thin film, wherein the longpass filter allows light with a wavelength longer than 7,000 nm to pass through, and blocks ambient light.
13. The optical device as claimed in claim 1 , further comprising a module lens disposed above the photon conversion thin film, wherein the module lens allows light with a wavelength longer than 7,000 nm to pass through and focuses heat on the photon conversion thin film.
14. The optical device as claimed in claim 7 , further comprising a thermal insulator disposed between the light source and the photon conversion thin film.
15. The optical device as claimed in claim 8 , wherein the light source comprises a light-emitting diode (LED) or a laser diode connected to the waveguide, and the light-emitting diode (LED) and the laser diode emit periodic pulse light or modulated sine wave light.
16. The optical device as claimed in claim 1 , further comprising an optical spacer with λ/4n±0.2 μm optical path inserted between a long-wavelength infrared (LWIR) reflection mirror and the photon conversion thin film to make an optical electric field of IR light located on the photon conversion thin film, wherein λ, is a wavelength of the IR light, and n is a refractive index of the optical spacer, wherein the LWIR reflection mirror comprises a stack of a first dielectric layer, a metal layer and a second dielectric layer, and the metal layer is sandwiched between the first dielectric layer and the second dielectric layer, wherein the first dielectric layer and the second dielectric layer have a refractive index greater than 1.3 and a thickness ranging from 5 nm to 200 nm, and the metal layer has a refractive index less than 1 in a visible region and a thickness ranging from 1 nm to 50 nm.
17. The optical device as claimed in claim 1 , further comprising a LWIR absorber layer with a thickness ranging from 5 nm to 500 nm disposed on the photon conversion thin film to enhance IR absorption, wherein the LWIR absorber layer comprises TiO 2 , SiO 2 or Al 2 O 3 .
18. The optical device as claimed in claim 15 , wherein emission of signals of the periodic sine wave light is synchronized with operation of a readout circuit, and the signals are read at various times by the readout circuit and converted into digital signals via an A/D converter, and a photoluminescence lifetime of the photon conversion thin film is calculated using equation (I) and converted into a temperature map, wherein
τ
=
-
t
ln
(
I
(
t
)
/
I
(
0
)
)
(
I
)
in equation (I), t represents time, I(0) represents initial signal intensity, I(t) represents signal intensity at time t, and τ represents the photoluminescence lifetime.
19. The optical device as claimed in claim 15 , wherein emission of signals of the modulated sine wave light is synchronized with operation of a readout circuit, and the signals are read at various phase delays by the readout circuit and converted into digital signals via an A/D converter, and a photoluminescence lifetime of the photon conversion thin film is calculated using equations (II) and (III) and converted into a temperature map, wherein
Δϕ
=
arc
tan
(
I
0
-
I
2
I
3
-
I
1
)
(
II
)
in equation (II), I 0 represents signal intensity at 0° phase delay, I 1 represents signal intensity at 90° phase delay, I 2 represents signal intensity at 180° phase delay, I 3 represents signal intensity at 270° phase delay, and Δφ represents phase difference between the light source and photon emitted from the photon conversion thin film, and
τ
=
tan
(
Δ
ϕ
)
2
π
v
(
III
)
in equation (III), Δφ represents the phase difference between the light source and photon emitted from the photon conversion thin film, ν represents light source modulation frequency, and τ represents the photoluminescence lifetime.