Pololu 38 kHz IR Proximity Sensor, Fixed Gain, Low Brightness
circuit to make a tiny proximity sensor. This low-brightness version draws an average of 8 mA at 5 V and has a typical sensing range up to approximately 12 inches (30 cm).
These sensor modules are based on Vishay’s TSSP77038 modulated infrared receivers. Unlike most IR receiver modules designed for remote control of appliances like televisions, the TSSP77038 has a fixed gain (sensitivity) that makes the sensor more predictable when used in proximity or reflectance sensors. The Pololu carrier module combines the TSSP77038 with an IR LED driven by a 555 timer-based circuit to make a complete sensor module that requires only a 3.3 V to 5 V power connection. An enable input allows control of whether or not the IR LED is on, and a digital output indicates whether or not an object is detected. The module is available in low-brightness and high-brightness versions, which provide detection ranges of up to approximately 12 inches (30 cm) and 24 inches (60 cm), respectively. The actual performance depends on many factors, including object size, reflectivity, and ambient lighting conditions.
more info: https://www.pololu.com/product/2579