A non-contact temperature measurement system for calculating estimated core body temperature is disclosed. The temperature measurement system can include a sensor that can detect temperature of a patient and temperature of ambient surrounding. The temperature of the patient and the ambient temperature can then be used to determine a core body temperature. The temperature measurement system includes an optical module having a light emitter and a light detector. The light emitter emits a beam of light towards the patient and the light detector detects a beam of light reflected by the patient. The reflected beam is analyzed to determine a distance between the temperature measurement system and the patient.