System Use and Description

The EOI series of primary standard blackbodies are pure elemental freezing point blackbody radiation sources for use as primary standards of spectral radiance. The ITS90 temperature scale is defined by the freezing points of pure elements. EOI freeze point blackbodies provide known spectral radiance at the ITS90 defined temperatures for gallium, indium, tin, zinc, aluminum, silver, gold and copper.

Configuration

The Multi-Point Primary Standard Blackbody system features interchangeable freeze point crucibles which minimizes the investment required to cover the entire ITS90 range of freeze point temps.

The system consists of an award winning EOI temperature controller, crucible holder and one or more of the interchangeable crucibles. The temperature controller provides automatic sequencing of melt and freeze, and a temperature display with freeze indicator. The crucible holder allows the use of interchangeable freeze point crucibles and provides for an optional gas curtain. The crucibles are easily interchanged, allowing testing at multiple freeze point temperatures with one economical system.

Variable Temperature Mode

The MPPS system can also be used as a variable temperature blackbody. In the variable temperature mode temperatures can be selected from 50°C to just below the melt temperature of the pure metal. Each crucible is calibrated over this range with traceability to . In this mode performance is the same as the EOI Secondary Standards series of blackbodies.

Emissivity

Each freeze point blackbody has a 0.25" diameter reverse cone cavity. The reverse cone configuration provides a highest effective emissivity, especially when compared to the more common straight cavity freezing. The cavity configuration and graphite material yield a 0.9997 ±0.0003 effective emissivity.

The graphite reverse conical cavity is surrounded by the pure melt material and takes on the temperature of the metal as it transitions from the liquid to frozen state. This transition or plateau remains constant at ±0.02°C or less. Freeze times are 20 to 40 minutes depending on the melt material, providing the time required to perform testing and calibration of the most sensitive infrared sensors, thermometers, imaging systems and radiometric devices.

EOI primary standard infrared sources have set the performance standard in the most demanding laboratories worldwide since 1964.

Controller

Each MPPS Series blackbody is supplied with a digital 19" rack mount controller.   In the variable temperature mode, the temperature of the blackbody can be set with 0.1°C resolution and actual temperature is displayed to 0.01°C on the front panel of the controller.

Menu Selections Include:

• Temperature Setting
• Display Resolution
• Remote/Local Control
• K, °C, or °F
• Ready Window Tolerance
• Interface Parameters
• Power On Configuration
• Self Test
• Calibration -- Accessed by User Assigned Password

Complete computerized control of the system is available through built-in interfaces.

• IEEE 488
• RS-232
• RS-422
• RS-485 

All four interfaces are resident in controller. The IEEE 488 and any one of the RS formats may be used at the same time.

Analog Output

An analog output is provided to interface to strip chart recorders or other analog recording devices.

Calibration

Each MPPS blackbody is calibrated over the vaiable operating range at EOI prior to shipment. Recommended calibration cycle is 6 months. Calibration is traceable to . The calibration table is stored in memory and is easily updated via the front panel keypad.

Case Temperature

The case temperature will never exceed 10°C above ambient.

Operating Ambient

The MPPS blackbody is designed to operate over an ambient temperature range of –40 to +60°C. The MPPS temperature controller will operate over an ambient temperature range of 0 to 50°C.

Note: A gas curtain is recommended when operating a graphite cavity above 500 °C.