Instrument response function monitor on an optical measurement device
An illustrative optical measurement system may include a module comprising a light source configured to emit light directed at a target, a plurality of detectors configured to detect target photon arrival times of target photons of the light after the light is scattered by the target, and a reference detector configured to detect reference photon arrival times of reference photons of the light after the light is reflected within the module. The system may further include a controller configured to determine, based on an output from the reference detector, an instrument response function (IRF) of the module.
1 . An optical measurement system comprising:
a module comprising:
a light source configured to emit light directed at a target,
a plurality of detectors configured to detect target photon arrival times of target photons of the light after the light is scattered by the target, and
a reference detector configured to detect reference photon arrival times of reference photons of the light after the light is reflected within the module; and
a controller configured to determine, based on an output from the reference detector, an instrument response function (IRF) of the module, wherein:
the module comprises a lower layer of components and an upper layer of components stacked above the lower layer of components within the module,
the plurality of detectors is positioned on the upper layer,
the reference detector is positioned on the lower layer, and
the light reflected within the module comprises light reflected in between the upper layer and the lower layer.
2 . The optical measurement system of claim 1 , wherein the controller is further configured to:
generate, based on the target photon arrival times and the reference photon arrival times, histogram data associated with the target; and
determine, based on the histogram data, a property of the target.
3 . The optical measurement system of claim 1 , wherein the reference detector is substantially identical to the plurality of detectors and shielded from the target photons.
4 . The optical measurement system of claim 1 , wherein:
the module comprises an additional light source configured to emit light directed at the target; and
the light source and the additional light source are positioned equidistant from the reference detector.
5 . The optical measurement system of claim 1 , wherein:
the light reflected within the module comprises light reflected off of an underside of the upper layer.
6 . The optical measurement system of claim 1 , further comprising:
an enclosure configured for the reference detector; and
an aperture in a wall of the enclosure configured to allow the light reflected within the module to reach the reference detector.
7 . The optical measurement system of claim 6 , wherein the aperture is configured to be adjustable to control an amount of the light reflected within the module to reach the reference detector.
8 . The optical measurement system of claim 1 , wherein the module further comprises a waveguide configured to direct the light reflected within the module to the reference detector.
9 . The optical measurement system of claim 8 , wherein a portion of the waveguide is positioned inside an optical assembly of the light source.
10 . The optical measurement system of claim 9 , wherein the portion of the waveguide positioned inside the light source comprises an optical element configured to direct photons of the light through the waveguide.
11 . The optical measurement system of claim 10 , wherein the optical element comprises a facet configured to reflect the light.
12 . The optical measurement system of claim 10 , wherein the optical element comprises a beam splitter configured to partially reflect the light.
13 . A wearable device comprising:
a wearable assembly;
a plurality of modules each configured to be selectively inserted into the wearable assembly, each module included in the plurality of modules comprising:
a light source configured to emit light directed at a target,
a plurality of detectors configured to detect target photon arrival times of target photons of the light after the light is scattered by the target, and
a reference detector configured to detect reference photon arrival times of reference photons of the light after the light is reflected within the module; and
a controller configured to determine, based on an output from the reference detector, an instrument response function (IRF) of the module, wherein:
the module comprises a lower layer of components and an upper layer of components stacked above the lower layer of components within the module,
the plurality of detectors is positioned on the upper layer,
the reference detector is positioned on the lower layer, and
the light reflected within the module comprises light reflected in between the upper layer and the lower layer.
14 . The wearable device of claim 13 , wherein the controller is further configured to:
generate, based on the target photon arrival times and the reference photon arrival times, histogram data associated with the target; and
determine, based on the histogram data, a property of the target.
15 . The wearable device of claim 13 , wherein the reference detector is substantially identical to the plurality of detectors and shielded from the target photons.
16 . The wearable device of claim 13 , wherein:
the module comprises an additional light source configured to emit light directed at the target; and
the light source and the additional light source are positioned equidistant from the reference detector.
17 . The wearable device of claim 13 , wherein:
the light reflected within the module comprises light reflected off of an underside of the upper layer.
18 . The wearable device of claim 13 , further comprising:
an enclosure configured for the reference detector; and
an aperture in a wall of the enclosure configured to allow the light reflected within the module to reach the reference detector.
19 . The wearable device of claim 18 , wherein the aperture is configured to be adjustable to control an amount of the light reflected within the module to reach the reference detector.
20 . The wearable device of claim 13 , wherein the module further comprises a waveguide configured to direct the light reflected within the module to the reference detector.
21 . The wearable device of claim 20 , wherein a portion of the waveguide is positioned inside an optical assembly of the light source.
22 . The wearable device of claim 21 , wherein the portion of the waveguide positioned inside the light source comprises an optical element configured to direct photons of the light through the waveguide.
23 . The wearable device of claim 22 , wherein the optical element comprises a facet configured to reflect the light.
24 . The wearable device of claim 22 , wherein the optical element comprises a beam splitter configured to partially reflect the light.