Thermoelectrically cooled photodiode for low-light-level detection in UV to near IR S2592/S3477 series sensors combine a UV to near infrared Si photodiode with a thermoelectric cooler. A thermistor is also included in the same package to sense the Si photodiode chip temperature. This allows stable operation over long periods of time, making these sensors suitable for low-light-level detection where a high S/N is required. S2592 series is hermetically sealed in a TO-8 package, and S3477 series in a TO-66 package. A dedicated temperature controller (C1103-04) and heatsink (A3179 series) are also available as options (sold separately).