4 Channel Relay Module Breakout Board (5V) motor drivers or simply the photocell

or simply the photocell

MLX90614ESF-BAA-000-TU-ND is a non-contact infrared thermometer for Arduino

In terms of still images

TTL/CMOS/PMOS/DTL compatible inputs

4 Channel Relay Module Breakout Board (5V) motor drivers or simply the photocellThis quad (4) channel Relay Module operates at 5V TTL signal and is perfect for common Arduino Raspberry Pi control applications. This is a 5V 4 Channel Relay interface board which can switch up to 10Amps. Relays terminals (C, NC, NO) are accessible through screw terminals which makes wiring up the board very easy. The relay is safely driven by transistor BC547 hence your input device, such as Arduino, is protected from relay circuit. There is flyback