Optical isolation apparatus

An apparatus comprising:

• an optical emitter mounted to a substrate;
• a transparent emitter housing portion enclosing the optical emitter and having an emitter housing sloped side wall extending from the substrate with a first emitter housing slope to a further emitter housing sloped side wall extending to an upper surface of the transparent emitter housing portion with a second emitter housing slope, wherein the first emitter housing slope is a constant slope and the second emitter housing slope is a constant slope less than the first emitter housing slope;
• a sensor for detecting light, the sensor mounted to the substrate;
• and
• a transparent sensor housing portion enclosing the sensor and having a sensor housing sloped side wall extending from the substrate with a first sensor housing slope to a further sensor housing sloped side wall extending to an upper surface of the transparent sensor housing portion with a second sensor housing slope, wherein the first sensor housing slope is a constant slope and the second sensor housing slope is a constant slope less than the first sensor housing slope, and wherein the transparent emitter housing portion and the transparent sensor housing portion are horizontally separated on the substrate by an air gap.