An optical leak detector (200) for use with a cooling system is described. The optical leak detector includes a light source (203), a light detector (205), and a conversion device (215). The light source is optically coupled to the light detector by way of an optical path (210). The light detector generates an electronic signal in response to light received from the light source. The conversion device, which is attached to the light detector, generates an electronic signal in response to the amount of light received from the light source. This electronic signal can indicate if a leak has occurred in the cooling system by the traversal of a entrapped gas bubble across the optical path formed by the light source and the light detector.