Takemi Inoue

Automatic Calorimeter System for the Effective Efficiency Measurement of a Bolometer Mount in 35-GHz Band

An automated calorimetric measurement system using a microcomputer has been developed for determining the effective efficiency of a bolometer mount in the millimeter-wave region. This system consists of a calorimetric measurement part, a bolometric measurement part, and a control/data processing part. The system has been constructed and experimented in 35-GHz band. The accuracy of the system has been estimated within ±0.37 percent.

Highly sensitive calorimeter for microwatt-level laser power measurements

A sensitive calorimeter using an isothermal temperature control technique was developed for an accurate measurement of microwatt-level laser power in the visible and infrared spectral region. The standard deviation of the measured value on 1-mW-1-μW laser power is 0.06–2 percent corresponding to the level. The systematic error is evaluated to be within ±0.23 percent for the 10 μW level.

Advanced Control Method for Calorimetric Power Measurement

An advanced temperature control system has been developed for calorimetric method of electromagnetic wave power measurement. The temperature deviation can be reduced by repeatedly substituting the controlled variable through a DA converter and an adder. The system has been applied to a calorimeter for laser power with experimental results yielding good agreement with analytical predictions.

A power measurement standard for W-band at 94 GHz

A dry monoload microcalorimeter and standard barretter mounts with effective efficiencies exceeding 85% have been used in the development of a 94-GHz power standard. The effective efficiencies of the standard barretter mounts are measured by a calorimeter with an uncertainty of 0.16%. A bolometer mount under test is calibrated to the standard barretter mounts with an uncertainty of 0.23%. Measurements and calibrations are fully automated using a desk-top computer. >

Newly Developed Bolometer Mounts for the Short Millimeter Wave Region

Two kinds of bolometer mounts have been recently developed at the Electrotechnical Laboratory (ETL) that are suitable for the millimeter wave region, especially for the short millimeter waves. They are 1) a matched-load-type bolometer mount and 2) a rising-sun-type bolometer mount. The former is the mount for measuring the rectangular waveguide power and the latter is for the circular TE01 mode waveguide power. Experimental mounts of both kinds have been designed and examined at 100 GHz. These mounts have demonstrated superior performance compared to those commercially available.

Automatic Calibration System for a Laser Power Meter

A microprocessor-based calibration system for a CW laser power meter has been developed. The system consists of an isothermal calorimeter with a thermopile unit, an electrical, and an optical subsystem. Temperature control of the thermopile unit is achieved through a digital technique. The calibration of a power meter is performed using the effective efficiency of the unit as measured by a calorimeter. From error analyses, an overall accuracy has been obtained as ±1 percent in root mean square for a power level of 1 ~ 200 mW.

A calorimeter for optical fiber power standard and advantages in calibration of optical fiber power meters

A calorimeter for optical fiber power measurement is developed. It has a compensative absorber to stabilize environmental disturbance, and two types of adapters for optical fibers and light beams. The uncertainty in measurements of 1-mW and 10- mu W optical fiber power was evaluated as +or-0.18% and +or-0.45% respectively, expressed as two standard deviations. The calibration uncertainty of an optical fiber power meter using the calorimeter as a primary standard is reduced by more than one half compared to that of the conventional method using a laser beam calorimeter and photodiode-type transfer standard. >

A Matched-Load Type PVF2 Pyroelectric Detector for Millimeter Waves

A practical pyroelectric detector for rectangular waveguide at 100 GHz has been constructed. This detector has the matched-load type structure and employs PVF2 as the pyroelectric material. The noise equivalent power of 8 nW/¿Hz has been obtained.

Automatic Bolometer Bridge Using an Adaptive Control Technique for RE Power Measurement

When RF power is measured using a bolometer bridge, generally its accuracy depends on the power level to be measured and the sensitivity of the bolometer mount in use. The former is principally due to the accuracy of bridge current measurement and the latter is due to an imperfection of bridge control. These are the dominant errors of the bridge measurement system. The objective of this paper is to design a bolometer bridge which offers an effective reduction of these errors and simplify its automation. As a result, a system introducing a digital control technique is proposed and tested.

Laser power meter with an integral alignment module

A reliable, fast‐beam alignment method for a thermal‐type laser‐power meter is proposed. The thermopile‐type power meter that has been developed and manufactured consists of a main‐sensor and a pinhole on the target, and a fast‐response sub‐sensor behind it. The alignment can quickly be performed by monitoring the beam‐power density of the incident‐laser beam. The method has been found to be very effective for beam alignment.