Optical sensor

An optical sensor comprising:

• two light emitters with a same or substantially a same temperature dependence of luminous intensity of the light;
• a light receiver;
• a reflector to reflect and diffuse light emitted by the light emitters and provided such that a portion of the reflected light is incident on the light receiver;
• an elastic support to support the reflector with respect to the two light emitters and the light receiver and deformable due to an external force to change a relative position of the reflector with respect to the two light emitters and the light receiver;
• and
• a processor configured or programmed to calculate a physical quantity that depends on an amount of deformation of the elastic support based on a ratio between two amounts of light received by the light receiver when respective ones of the two light emitters emit light at different timings;
• wherein
• the two light emitters and the light receiver are fixed relative to each other;
• and
• a distance from one of the two light emitters to the light receiver is different from a distance from another light emitter of the two light emitters to the light receiver.