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, 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 waveguide configured to direct the light reflected within the module through a plurality of channels of the waveguide to the reference detector. 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,
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 waveguide configured to direct the light reflected within the module through a plurality of channels of the waveguide to the reference detector; and
a controller configured to determine, based on an output from the reference detector, an instrument response function (IRF) of the module.
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 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 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 a portion of the waveguide is positioned inside an optical assembly of the light source.
9 . The optical measurement system of claim 8 , wherein the portion of the waveguide positioned inside the light source comprises an optical element configured to direct photons of the light through the channels of the waveguide.
10 . The optical measurement system of claim 9 , wherein the optical element comprises a facet configured to reflect the light.
11 . The optical measurement system of claim 9 , wherein the optical element comprises a beam splitter configured to partially reflect the light.
12 . The optical measurement system of claim 9 , wherein the waveguide further comprises an additional optical element at a center of the waveguide configured to deflect the photons of the light directed through the channels of the waveguide to the reference detector.
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,
a reference detector configured to detect reference photon arrival times of reference photons of the light after the light is reflected within the module, a waveguide configured to direct the light reflected within the module through
a plurality of channels of the waveguide to the reference detector; and
a controller configured to determine, based on an output from the reference detector, an instrument response function (IRF) of the module.
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 a portion of the waveguide is positioned inside an optical assembly of the light source.
17 . The wearable device of claim 16 , 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.
18 . The wearable device of claim 17 , wherein the optical element comprises a facet configured to reflect the light.
19 . The wearable device of claim 17 , wherein the optical element comprises a beam splitter configured to partially reflect the light.
20 . The wearable device of claim 16 , wherein the waveguide further comprises an additional optical element at a center of the waveguide configured to deflect the photons of the light directed through the channels of the waveguide to the reference detector.