ORIEL PRODUCT LINE 150 Long Beach Boulevard Stratford, CT 06615 Phone (203) 377-8282 (800) 714-5393 Fax: (203) 378-2457 E-MAIL: oriel.sales@newport.com MODEL 71887 USER MANUAL Please read these instructions completely before operating this equipment. The specification and operating instructions apply only to the model(s) covered by this manual. If there are any questions or problems regarding the use of this equipment, please contact Newport or the representative from whom this equipment was purchased.
TABLE OF CONTENTS I. INTRODUCTION... 3 II. DESCRIPTION... 4 III. CALIBRATION... 9 IV. WARRANTY AND RETURNS... 10
I. INTRODUCTION The ORIEL Model 71887 is a cooled InGaAs detector head that features 3 mm diameter InGaAs photodetector with a low noise transimpedance amplifier. The 71887 covers the detection range of 0.8 to 1.7 µm. The detectors operate in the unbiased (photovoltaic) mode for lowest noise and highest linearity. Switches allow transimpedance gain (10 4 to 10 9 ) and time constant selection. The detector has a 2 stage TEC (thermoelectric cooler) which can cool the detector to approximately 50C below ambient. This cooling provides a stable responsivity, especially at the extremes of the spectral range, and reduces the noise resulting from the small bandgap. These detectors are general purpose devices that will typically be run with a laboratory power supply like the Oriel models 70703/09. Therefore, a power cable is supplied as well as a BNC cable to connect to your measuring device. An additional cable, incorporating both power and signal is provided so that the detector can be run with an Oriel OPM (model 70310) or Merlin (models 70100 et al.). A calibration option is available. This package you have received should contain: Cooled InGaAs Detector Head. Oriel part number 70328. Cable, Detector Head Power; 5 pin mini-dip to triple banana plug. Oriel part number 70055. Cable, Detector Head Cooler; 4 pin LEMO to 9 pin D-sub. Oriel P/N 70062. Cable, low noise BNC. Oriel part number 70016. Table of thermistor resistance versus temperature for setting up the cooler controller. This manual. Optional Calibration. Calibration data is provided in several forms. 3
II. DESCRIPTION SPECTRAL RESPONSE Figure 1: Shows the spectral response of our Cooled InGaAs Detector Head. Cooling the detector ensures stable long term response. These Cooled InGaAs Detector Heads include JFET operational amplifiers and selectable precision feedback resistors for matching the output voltage level to the input power range. 4
SETTING GAIN AND TIME CONSTANT The switches for setting gain and time constant are located on the detector cover. The gain should be set as high as practical to give the best signal resolution. For a given gain, the time constant may be set to a higher value to reduce noise, especially in DC systems, although response time will suffer. With chopped systems care must be taken so that the amplifier bandwidth limitation does not significantly affect the chopped signal wave shape: the bandwidth of the amplifier should be at least 5 times the chopper frequency. Consult the following table for the gain/bandwidth limitations. To assist in setting the gain, connect a voltage measuring device - an oscilloscope or a meter - to the BNC on the detector and monitor the output voltage while changing the gain settings. When setting the gain for DC, or slowly varying, measurements you want to be sure that the output voltage is at least 2 volts away from the power supply rail (the power supply from the model 70310 OPM is ± 5 volts, the 70703 power supply and Merlin provide ±15 volts) with maximum input signal. Some margin is advisable. For purposes of setting the gain, you probably do not want to use the MAX time constant setting because of the resultant slow change of the output voltage. You should also pay attention to the dark output voltage generated by the detector/amplifier and reference your DC measurements to that level. For AC, or chopped, signals you must be wary of DC saturation problems associated with high levels of background light. In this case the output will be asymmetrical with respect to ground and, although this offset should not affect most AC measuring systems, you need to insure that the peak light voltage stays at least 2 volts away from the power supply rail as stated above. For Merlin, the peak signal should not be greater than 10 volts. This check can be done easily with an oscilloscope. With a meter it may be necessary to either stop the chopper in the open position or remove it entirely from the system in order to verify the peak voltage reading. Bandwidth (BW) Gain and Time Constants Time Constant Setting MIN MED MAX BW -3dB BW -3dB BW -3dB GAIN, V/A 10 4 10 5 10 6 10 7 10 8 10 9 100 khz 10 khz* 3 khz* 1 khz* 100 Hz 10 Hz 100 khz 10 khz 1 khz 100 Hz 10 Hz 1 Hz 1 khz 100 Hz 10 Hz 1 Hz 0.1 Hz 0.01 Hz * There is significant bandwidth above these frequencies, but peaking in the amplifier circuit affects the absolute gain value. 5
CONVENIENT MOUNTING Each detector head has a tapped hole for rod mounting and an ORIEL 1.5 inch Series Female Flange. This flange mounts the detector head to ORIEL Monochromators and accepts a variety of filter holders and other optical accessories. CABLES There are four cables supplied with the detector. For general purpose usage, a power cable and separate BNC cable for signal are provided. Another cable is included for OPM/Merlin applications where the power for the detector amplifier and the detector output signal are carried in one cable. The fourth cable connects the detector head to the Oriel model 77057/58 TE Cooler Controller. Typically the 6 ft. (1.8 m) screened cable connects the head to a ± 15 V dc power supply (± 5 V is OK if the reduced output voltage swing is acceptable) for the preamplifier power. The power cable is terminated with a triple banana plug which mates with the Oriel model 70703/09 power supply and many others. At the banana plug the red wire is +15 volts, the orange wire is ground and the yellow wire is -15 volts. RED ORANGE G N D YELLOW BRAID +15VDC 2 RED 1 COMMON 3 ORANGE 2-15VDC SIGNAL 4 1 YELLOW BROWN NC TAB 3 RETURN 5 BLUE NC Figure 2: Cable, Detector Head power A BNC connector on the rear panel provides a convenient place for monitoring the signal out of the head. The output signal from the detector head is also carried in the power cable; the brown wire is the signal and the blue wire is signal return. These two wires and the cable shield have been cut back at the banana plug because of the convenience of the BNC. The power cable may be re-terminated to meet your specific needs. 6
For OPM/Merlin applications the one cable services both power and signal. Just connect the cable between the detector and the measuring device. The cooler cable connects the detector to the Oriel 77057/77058 Cooler Controller providing power to TEC in the head and returning temperature information from the thermistor sensor. The resistance versus temperature data for the temperature sensor is included with the detector documentation. The current limit for the cooler should be set for approximately 1 amp. Figure 3: Cable, Detector Head to Cooler Control 7
Figure 4: Dimensional Drawing of Cooled InGaAs Detector Head 8
III. CALIBRATION If the detector is calibrated, the dc responsivity data in amps/watt is provided. This data can be used in conjunction with the gain setting of the amplifier to relate the voltage output of the detector head to the power impinging on the detector element or the source power. power [watts] = voltage measured [volts] / (responsivity [amps/watt] x amplifier gain [volts/amp]). If the signal being measured is ac, the calibration factors should be adjusted to reflect the measuring technique. For example, if the source is dc but there is a chopper between the source and detector, the energy that reaches the detector might be a square wave. In this case, an rms measurement of the detector output voltage will be reduced from the dc value (the dc value divided by the square root of 2) and a lock-in responding to the rms of the fundamental (chop) frequency will measure even lower ({the square root of 2 over pi} times the dc value). The responsivity values have to be reduced proportionately if the measurement is meant to reflect the value at the dc source - Merlin calibration data has this correction applied. The data is loaded into a calibration PROM which is part of the OPM/Merlin cable provided. If the detector is being used with the OPM, the data is loaded at power on and the dc responsivity is applied to the reading at the selected wavelength when WATTS is selected. Transimpedance gain and any other measurement factors have to be applied through the ATTENUATION menu. 9
IV. WARRANTY AND RETURNS Newport warrants that all goods described in this manual (except consumables such as lamps, bulbs, filters, ellipses, etc.) shall be free from defects in material and workmanship. Such defects become apparent within the following period: 1. All products described here, except spare parts: one (1) year or 3000 hours of operation, whichever comes first, after delivery of the goods to the buyer. 2. Spare parts: ninety (90) days after delivery of goods to the buyer. Newport s liability under this warranty is limited to the adjustment, repair and/or replacement of the defective part(s). During the above listed warranty period, Newport shall provide all materials to accomplish the repaired adjustment, repair or replacement. Newport shall provide the labor required during the above listed warranty period to adjust, repair and/or replace the defective goods at no cost to the buyer ONLY IF the defective goods are returned, freight prepaid, to a Newport designated facility. If goods are not returned to Newport, and the user chooses to have repairs made at their premises, Newport shall provide labor for field adjustment, repair and/or replacement at prevailing rates for field service, on a portal-to-portal basis. Newport shall be relieved of all obligations and liability under this warranty of: 1. The user operates the device with any accessory, equipment or part not specifically approved or manufactured or specified by Newport unless buyer furnishes reasonable evidence that such installations were not the cause of the defect. This provision shall not apply to any accessory, equipment or part which does not affect the safe operation of the device. 2. The goods are not operated or maintained in accordance with Newport s instructions and specifications. 3. The goods have been repaired, altered or modified by other than authorized Newport personnel. 4. Buyer does not return the defective goods, freight prepaid, to a Newport facility within the applicable warranty period. IT IS EXPRESSLY AGREED THAT THIS WARRANTY SHALL REPLACE ALL WARRANTIES OF FITNESS AND MERCHANTABILITY. BUYER HEREBY WAIVES ALL OTHER WARRANTIES, GUARANTEES, CONDITIONS OR LIABILITIES, EXPRESSED OR IMPLIED, ARRISING BY LAW OR OTHERWISE, WHETHER OR NOT OCCASIONED BY NEWPORT S NEGLIGENCE. This warranty shall not be extended, altered or varied except by a written document signed by both parties. If any portion of this agreement is invalidated, the remainder of the agreement shall remain in full force and effect. CONSEQUENTIAL DAMAGES Newport shall not be responsible for consequential damages resulting from misfunctions or malfunctions of the goods described in this manual. Newport s total responsibility is limited to repairing or replacing the misfunctioning or malfunctioning goods under the terms and conditions of the above described warranty. INSURANCE Persons receiving goods for demonstrations, demo loan, temporary use or in any manner in which title is not transferred from Newport, shall assume full responsibility for any and all damage while in their care, custody and control. If damage occurs, unrelated to the proper and warranted use and performance of the goods, recipient of the goods accepts full responsibility for restoring the goods to their condition upon original delivery, and for assuming all costs and charges. RETURNS Before returning equipment to Newport for repair, please call the Customer Service Department at (203) 377-8282. Have your purchase order number available before calling Newport. The Customer Service Representative will give you a Return Material Authorization number (RMA). Having an RMA will shorten the time required for repair, because it ensures that your equipment will be properly processed. Write the RMA on the returned equipment s box. Equipment returned without a RMA may be rejected by the Newport Receiving Department. Equipment returned under warranty will be returned with no charge for the repair or shipping. Newport will notify you of any repairs not covered by the warranty, with the cost of the repair, before starting the work. Please return equipment in the original (or equivalent) packaging. You will be responsible for damage incurred from inadequate packaging, if the original packaging is not used. Include the cables, connector caps and antistatic materials sent and/or used with the equipment, so that Newport can verify correct operation of these accessories. 10