Datasheet EMIRS200_v1-3

Microsystems

CH-6060 Sarnen

Datasheet EMIRS200

Electrically modulated IR Source

Features

Thermal black body source

Broad band IR emission

Electronically pulsed, no moving parts

Fast heating and cooling rates

Wide modulation frequency band

Low power consumption

Long term stability

Compact packaging TO39, 3 pins

Applications

Infrared spectroscopy

Non dispersive infrared detection

Photacoustic gas detection

EMIRS200

Product Summary – principle of operation

The EMIRS200 is a versatile thermal infrared light emitter. The emission can be

directly modulated by varying the electrical input signal. This device is best suited to

replace existing, mechanically chopped lamp solutions, thus eliminating moving

parts. Conventional lamps with Tungsten filaments work under vacuum and are

therefore encapsulated in glass. This protection is no longer transparent for

wavelengths exceeding 5 µm and limits their application range. The EMIRS200

exhibits a broadband IR emission from NIR to 20 µm.

The EMIRS200 is based on a silicon chip using advanced microstructure fabrication

technologies. It consists of a thin film resistor supported on a thermally and

electrically insulating membrane. The heating relies on the Joule effect in the

microfilament. The low thermal mass of the supporting membrane structure permits

to heat and cool the microfilament with very short time constants of 11 ms and 17 ms

respectively. This allows a fast direct modulation of the emitted infrared light. A

unique patented technology allows manufacturing of highly reliable modulated IR

sources with true black body characteristics and very high emissivity. Emissivity

higher than 0.9 is achieved for wavelengths up to 15 µm.

EMIRS200 Preliminary Datasheet Feb. 2004 1/8

Microsystems

CH-6060 Sarnen

Datasheet EMIRS200

The main characteristic of heat

radiation is that absorption and

emission are equal when the device is

at thermal equilibrium. This means that

the higher the absorption, the higher

the emissivity. The emissivity of the

EMIRS200 microfilament is enhanced

by creating a random surface structure

as shown in figure 1. Incoming light is

absorbed by this surface resulting in a

low reflectivity. This is the reason why

the EMIRS200 sources appear black

and exhibit an excellent emissivity

Figure 1: SEM view of the structures enhancing the

close to 1.

emissivity of the device.

Absolute maximum ratings

Characteristics

Cold resistance

Operating Temperature

Storage temperature range

Rating

55

-20/+85

-40 /+125

Unit

Ohm

°C

°C

°C

Case temperature (cw, 600 mW) 90

Electrical/Optical characteristics (Tc=25°C)

Parameter

Cold Resistance

Hot Resistance

Electrical input power

Operating voltage

Operating current

Heating time constant

Cooling time constant

Peak emission wavelength

Emissivity

Lifetime (measured)

Heating area

Case Temperature

Min

35

0.9

Typ

45

72

450

5.7

80

11

17

4.0

0.95

>40’000

2.1x1.8

47

Max

55

6.3

90

Unit Conditions

Ω

Ω

mW

V

mA

ms

ms

µm

hours

450 mW

end of heating cycle

450 mW

450 mW

450 mW

VIS to 15 µm

50% duty cycle, 30 Hz, 450 mW,

ongoing measurement

2mm

°C 50% duty cycle; 450 mW

EMIRS200 Preliminary Datasheet Feb. 2004 2/8

Microsystems

CH-6060 Sarnen

Datasheet EMIRS200

Operating conditions

The source can be operated in continuous (cw) or in pulsed mode. Its fast heating

and cooling time constants of 11 ms and 17 ms respectively make it ideal for

detection schemes that rely on a modulated light source, such as photoacoustic

detection and phase sensitive techniques for the suppression of DC components and

the reduction of 1/f noise.

The heating element exhibits a high TCR value. This means that a current flowing

through the resistor induces a self-heating of the element and therefore an increase

in the resistor value. The data in figure 2. show the typical rise in resistance with

increasing electrical power.

61

U

[V]420100

I

[mA]50

060

Resistance

[Ω]R

[Ω]40200600

403020100P

[mW]40020001.00.50.0

E

[norm.]0500600

0.00.20.40.60.81.0Electric Power [mW] Time [s]

Figure 2: Typical increase of the source

resistance as a function of the electrical heating

power in thermal equlibrium. The dashed lines

indicate the range for the specified minimum

and maximum cold resistance values.

Figure 3: Time evolution of the driving voltage (V),

current (I), resitance (R), electrical power (P) and

total IR emission (E) of a typical IR source in

pulsed mode (voltage driven).

The source can driven with a square wave in constant voltage or in constant

current mode. The time evolution of the various parameters during a square wave

modulation with constant voltage is depicted in figure 3. Due to the lower resistance

at the beginning of the heating cycle, the current and the input power exhibit an

overshoot. Therefore the constant voltage mode supports slightly faster heating rates

compared to the constant current mode.

The frequency response of the total IR emission in figure 4 has been measured with

a driving square wave voltage of constant amplitude. The modulation depth is

EMIRS200 Preliminary Datasheet Feb. 2004 3/8

Microsystems

CH-6060 Sarnen

Datasheet EMIRS200

defined as the amplitude of the sine component at the fundamental frequency of the

driving square wave. A modulation depth of 50% is achieved at 24 Hz. The

modulation depth can be further enhanced significantly in a constant temperature

mode, i.e. the drive voltage is increased for higher frequencies to maintain the same

peak temperature at the end of the heating cycle. This mode works best for

asymmetric duty cycles with shorter heating periods.

Relative

Signal-Amplitude10.1110100Modulation Frequency [Hz]

Figure 4: Signal modulation depth of the total IR emission as a function of modulation frequency

(square wave voltage with constant amplitude, 50:50 duty cycle).

Emission spectrum

Figure 5: Typical emission spectra of the EMIRS200 for different electrical input powers.

The EMIRS200 exhibits true black-body characteristics. The emission spectra in

figure 5 have been measured with a Fourier transform IR spectrometer for different

electrical power levels. The measured curves have been fitted with a Planck

distribution function. The spectra show excellent agreement with the theoretical black

body emission. The extracted source temperature varies from 350°C to 550°C, the

peak wavelengths are situated at about 3.5 µm to 4.5 µm.

EMIRS200 Preliminary Datasheet Feb. 2004 4/8

Microsystems

CH-6060 Sarnen

600550

Datasheet EMIRS200

3.5Temperature

[°C]5505504.555.56600Electrical Power [mW]Figure 6: Source temperature and corresponding peak wavelength λmax versus electrical power as

extracted from the emission spectra.

λmax

[µm]4504

Lifetime

Lifetime tests are permanently ongoing. These are performed for square modulation

with 30 Hz frequency and 50 : 50 duty cycle at electrical power levels of 350 mW,

400 mW and 450 mW. Over the measured 40’000 h, no degradation has been

observed. The measured intensity variation was within the accuracy of the optical

detector (± 5%). The sources have been operated at ambient atmosphere, which

indicates that a hermetic sealing of the TO package is not required. The use of the

source at maximum ratings may result in a shorter life than operation at lower

temperatures.

110IR-Emission

in

%

of

Starting

Value1441200350 mW400 mW450mWTime [days]Figure 7: Long-term stability test lasting since more than 40’000 hours with power levels of 350 mW,

400 mW and 450 mW (30 Hz, 50:50 duty cycle).

EMIRS200 Preliminary Datasheet Feb. 2004 5/8

Microsystems

CH-6060 Sarnen

Datasheet EMIRS200

Case temperature

The temperature of the TO39 header has been measured at different power levels in

cw and pulsed mode.

100Temperature

[°C]806040cw50:50 duty cycle20500600Electrical Power [mW]Figure 8: Typical housing temperature (Tc=21°C) versus electrical power for cw and pulsed operation

(50:50 duty cycle).

EMIRS200 Preliminary Datasheet Feb. 2004 6/8

Microsystems

CH-6060 Sarnen

Datasheet EMIRS200

Packaging information

The device is supplied in a TO 39 header

type package with 3 pins. Pin 1 and 2 are

isolated and pin 3 is grounded. A cap with

round opening protects the silicon chip.

Standard executions are delivered

without protective window. Various

windows and filters are available on

request.

The typical weight of an EMIRS200 is

900 mg.

Soldering

The terminations of the TO39 package

consist of Nickel-plated Kovar and gold

finish. Hand soldering is mandatory.

Cleaning procedures are not

recommended as they might reduce the

emitting efficiency or even destroy the

device.

Pin-Out

Pin

1

2

3

Function

Heating resistor Rh

Heating resistor Rh

Ground

3

2

1

Figure 9: Package outline dimensions (in mm).

EMIRS200 Preliminary Datasheet Feb. 2004 7/8

Microsystems

CH-6060 Sarnen

Datasheet EMIRS200

ESD (Electrostatic discharge)

Electrostatic discharge and other current surges can cause deterioration and damage

of the IR source. Handling of the device has to be done according ESD rules.

Electronic circuitry should be designed to avoid the generation of excessive current

spikes when the power is turned on and the device should be protected against

electrostatic discharges.

Liability Policy

Technical data and specifications contained herein are subject to change without

prior notice.

As any semiconductor device, LEISTER Process Technologies micro-machined

devices have inherently a certain rate of failure. It is the responsibility of the buyer to

comply with the standards of safety in making a safe design for the entire system, to

protect against injury, damage or loss from such failures.

The products listed in this document are neither intended nor warranted for special

applications where failure or malfunction may affect human life or cause physical

injury or damage to property. LEISTER Process Technologies will not be responsible

for damage arising from such use.

USA Headquarter

LEISTER Process Technologies LEISTER Technologies LLC

Microsystems Division 1253 Hamilton Parkway

CH-6060 Sarnen/Switzerland Itasca, IL 60143/USA

phone (630) 760 1000 Phone + 41 41 662 74 74

Fax (630) 760 1001 Fax + 41 41 660 20 61

e-mail: microsystems@ e-mail: sales@

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Copyright © 2004 LEISTER Process Technologies, Microsystems Division, CH-6060

Sarnen

EMIRS200 Preliminary Datasheet Feb. 2004 8/8