| CPC H04R 1/1041 (2013.01) [A61B 5/0059 (2013.01); A61B 5/441 (2013.01); A61B 5/681 (2013.01); A61B 5/6817 (2013.01); G02B 5/281 (2013.01); H04R 1/1016 (2013.01); A61B 2503/12 (2013.01)] | 16 Claims |

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1. A skin sensor configured to detect a presence of skin using reflectance measurements from a target at a first wavelength and at a second wavelength at which skin reflects less than at the first wavelength, comprising:
a first light-emitting device configured to emit light at the first wavelength;
a second light-emitting device configured to emit light at the second wavelength;
a first bandpass filter that has a first pass band at the first wavelength and that overlaps the first light-emitting device;
a second bandpass filter that has a second pass band at the second wavelength and that overlaps the second light-emitting device, wherein the second bandpass filter meets the first bandpass filter at a seam, and wherein the emitted light at the first and second wavelengths that has passed respectively through the first and second bandpass filters is characterized by an angular spread of less than +/−30°;
an opaque masking layer that overlaps a portion of the first bandpass filter, a portion of the second bandpass filter, and the seam; and
a photodetector configured to measure the emitted light at the first wavelength after passing through the first bandpass filter and reflecting from the target and configured to measure the emitted light at the second wavelength after passing through the second bandpass filter and reflecting from the target.
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