1.1 CoolingControl Introduction

CoolingControl is the GenICam feature set for cooling control on the Hamamatsu C15550‑22UP camera. It manages thermoelectric (Peltier) cooling for the image sensor.

The C15550‑22UP uses a Peltier thermoelectric cooler to lower the temperature of the qCMOS image sensor. Cooling the sensor significantly suppresses dark current and thermal noise, enabling long‑exposure imaging, low‑light imaging and improved quantitative accuracy. This is key to achieving the camera’s ultra‑low dark current of 0.006 e⁻/pixel/s.

The CoolingControl feature set includes two properties:

• CoolerSelector (Cooler Selector): Selects the cooler device; Peltier for this camera
• CoolerMode (Cooler Mode): Sets cooler operating mode. Valid values: Off / On(Mode1) / Max(Mode2)

Key characteristics:

• Cooling device: Peltier element. Cold side absorbs heat from sensor; hot‑side heat is dissipated by fan (air‑cooled) or circulating water (water‑cooled).
• Two cooling methods: Forced‑air cooled (factory default) / Water cooled (optional circulating chiller)
• Three cooling modes: Off / On (Mode1) / Max (Mode2) — configurable only under water‑cooled mode
• Typical achievable temperature: approx. ‑20 °C for air‑cooled or standard water‑cooled; down to ‑35 °C for water‑cooled Max mode
• Cooling method (Air/Water) must be changed via DCAM Configurator and requires a camera reboot to take effect

2.1 Peltier Cooling Principle

When powered, a Peltier element creates a cold side (heat absorption) and a hot side (heat dissipation). The CMOS image sensor is mounted on the cold side for heat removal. Heat generated on the hot side must be dissipated promptly, otherwise cooling efficiency degrades.

Built‑in thermal protection circuitry automatically cuts power to the Peltier device when internal temperature rises abnormally to protect hardware. Normal operation resumes after temperatures return to safe range.

2.2 Forced‑air Cooled (Default)

The Peltier hot side is cooled by the camera’s built‑in fan. The fan starts spinning at power‑on and cooling activates automatically; no external equipment is needed.

• Cooling performance: Sensor reaches approx. ‑20 °C at ambient +25 °C
• Advantages: Out‑of‑box, simple installation for general‑purpose imaging
• Limitation: CoolerSelector and CoolerMode show status “Not Available” and are greyed‑out within ImgGrab and cannot be modified.

2.3 Water Cooled (Optional)

Heat from the Peltier hot side is carried away by an optional circulating water chiller. Water cooling delivers superior heat dissipation, better temperature stability and lower achievable sensor temperatures.

• Cooling performance: approx. ‑20 °C (chiller / ambient +25 °C); down to ‑35 °C typical for Max mode (chiller / ambient +20 °C)
• Cooling will NOT start with camera power‑on alone: Start the circulating chiller first and confirm proper water flow before enabling camera cooling in software.
• Recommended water temperature: 25 °C, flow rate approx. 0.45 L/min. Never stop the chiller while camera is running.
• Use soft water only. Pure water or hard water may cause corrosion, scaling, flow reduction or blockage inside water lines.
• CoolerMode (Off / On / Max) becomes configurable only after switching to water‑cooled mode.

Figure 1 Connection diagram of circulating chiller and Hamamatsu C15550‑22UP camera

3.1 Core Parameters

Note: CoolerSelector is a selector‑type feature. CoolerMode values are linked to the selected cooler. Changing CoolerSelector invalidates and refreshes CoolerMode current value.

3.2 CoolerMode Operating Modes

Note: GenICam enumeration names are Mode1 / Mode2, displayed as Mode1 / Mode2 in GUI software. Under water‑cooled configuration, ImgGrab dropdown shows Off / Mode1 / Mode2.

Important Notes:

• Cooling method (Air / Water) cannot be switched within ImgGrab CoolingControl. Use DCAM Configurator to modify Cooler Type and reboot camera for changes to apply.
• CoolerMode selection between Off / Mode1 / Mode2 is available only under water‑cooled mode.

5.1 Achievable Cooling Temperature

5.2 Dark Current vs Temperature

At ‑35 °C under Max cooling mode, dark current reaches approximately 0.006 e⁻/pixel/s, well‑suited for long‑exposure measurements. Lower and more stable sensor temperature yields lower dark‑current and better quantitative repeatability.

5.3 Condensation Protection

Condensation risk increases under water‑cooled operation when ambient temperature and humidity are high. Operate within non‑condensing environmental limits; refer to official manual for temperature‑humidity envelope. Condensation risk is highest under water‑cooled Max mode (chiller set to 20 °C), strictly control ambient humidity in such scenarios.

6.1 Scenario 1: Long‑exposure & Low‑light Imaging

Settings: Cooling method = Water cooled, CoolerMode = On (or Max)

Effect: Sensor cooling drastically reduces dark‑current; background noise is suppressed for long exposure captures.

Applications: Astronomical lucky imaging, single‑molecule fluorescence, bioluminescence and other low‑light long‑exposure experiments.

6.2 Scenario 2: Minimum Dark‑Current (Max Cooling)

Settings: Water‑cooled (chiller / ambient +20 °C), CoolerMode = Max (Mode2)

Effect: Sensor cools down to approx. ‑35 °C with dark‑current ~0.006 e⁻/pixel/s.

Applications: Ultra‑low‑noise quantitative measurement, ultra‑long exposure acquisition.

6.3 Scenario 3: High Temperature Stability Requirement

Settings: Water‑cooled, CoolerMode = On

Effect: Water cooling delivers superior sensor temperature stability for extended continuous quantitative acquisition.

Applications: Long‑term experiments sensitive to thermal drift. Air‑cooled is suitable for general‑purpose use where extreme low temperature is not required.

7.1 Greyed‑out CoolerMode under Air‑cooled is Normal

When operating in Forced Air Cooling mode, CoolerSelector and CoolerMode report “Not Available” and appear greyed‑out inside ImgGrab. This is expected hardware behaviour, not a fault. Configuration access is unlocked only after switching to water‑cooled mode.

7.2 Cooling Method Change Requires Camera Reboot

Air / Water cooling mode cannot be changed inside ImgGrab CoolingControl. Open DCAM Configurator → Hardware tab → modify Cooler Type. A camera restart is mandatory for changes to take effect, applies both directions.

7.3 Water‑cooled: Start chiller BEFORE enabling camera cooling

Correct workflow: Start circulating water chiller → Verify stable water flow (~0.45 L/min) → Enable camera cooling in software. Never stop chiller while camera is running; loss of flow will disable cooling and may trigger thermal protection.

7.4 Water Quality and Flow Requirements

Soft water is required. Avoid pure water or hard water to prevent corrosion, scaling and water‑line blockage. Recommended water temperature 25 °C, flow rate ~0.45 L/min. Replace hoses if flow cannot be maintained.

7.5 Condensation Prevention

High ambient humidity combined with water‑cooled operation creates condensation hazard. Operate within non‑condensing environmental limits, refer to manual temperature‑humidity chart when necessary.

7.6 Power‑down Sequence & Ventilation

For water‑cooled setup: Disable camera cooling in software first, then shut down circulating chiller. For air‑cooled operation, keep camera ventilation openings unobstructed for proper heat exhaust.