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Through the photovoltaic effect, detectors provide a means of transforming light energy to an electrical current. The root of the theory behind this phenomenon is a small energy gap between the valence and conduction bands of the detector. When light, with enough energy to excite an electron from the valence to the conduction band, is incident upon the detector, the resulting accumulation of charge leads to a flow of current in an external circuit. Since light is not the only source of energy that can excite an electron, detectors will have some amount of current that is not representative of incident light. For example, fluctuations in thermal energy can easily be mistaken for light intensity changes. A variety of these “non-light” contributions are present and, when summed up, make up the total noise within the detector.
The ratio of the overall signal output to the noise level is known as the signal to noise ratio (S/N) and can be used to determine if noise will be a concern within a particular application. While noise is certainly a key means of characterizing detectors, it is only one of the characteristics which should be considered when selecting a detector. Some key issues regarding detectors are outlined in the terms and definitions box to the left.
Different Operation Modes
Photovoltaic (Unbiased): During PV operation, no external bias is applied to the photodiode. Since Dark Current is a function of bias magnitude, PV operation eliminates Dark Current as a source of noise. In this case, the NEP will be lower, thereby allowing greater sensitivity at lower wavelengths. This makes it ideal for low signal detection. One disadvantage is the slightly lower responsivity at higher wavelengths (see graph).
Photoconductive (Biased): During PC operation, a reverse bias on the photodiode results in a number of response advantages, such as a faster rise time. This makes this type of operation more suitable for high frequency applications. One inconvenience is that the dark current increases with this applied biased current, so noise is introduced into the system.
For #57-511 and #57-512: Housing is smaller than standard TO-5 mount. Maximum housing outer diameter is 0.187", whereas typical TO-5 is 0.36".
For #53-374: Housing is larger than standard BNC mount. Maximum housing outer diameter is 1.675", whereas typical BNC is 0.975".
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| Description | Stock No. | Price | In Stock | |||||||||||
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Showing 1-20 of 25 Items | Show All Items
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Silicon Detector, Normal Response, 0.20mm Sq
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NT57-506 | $19.00 |
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Silicon Detector, Normal Response, 0.81mm Sq
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NT57-507 | $19.00 |
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Silicon Detector, Normal Response, 3.2mm Sq
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NT53-372 | $19.00 |
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Silicon Detector, Normal Response, 5.1mm Sq
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NT53-371 | $31.00 |
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Silicon Detector, Normal Response, 16.4mm Sq
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NT54-034 | $34.00 |
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Silicon Detector, Normal Response, 44.0mm Sq
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NT54-035 | $49.00 |
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Silicon Detector, Normal Response, 100.0mm Sq
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NT53-373 | $99.00 |
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Silicon Detector, Normal Response, 613.0mm Sq
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NT53-374 | $335.00 |
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Silicon Detector, High Speed Response, 0.85mm Sq
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NT57-512 | $48.00 |
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Silicon Detector, High Speed Response, 5.1mm Sq
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NT54-520 | $51.00 |
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Silicon Detector, High Speed Response, 15.0mm Sq
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NT55-338 | $69.00 |
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Silicon Detector, Blue Enhanced Response, 0.81mm Sq
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NT57-508 | $22.00 |
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Silicon Detector, Blue Enhanced Response, 5.1mm Sq
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NT53-378 | $28.00 |
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Silicon Detector, Blue Enhanced Response, 100.0mm Sq
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NT53-379 | $99.00 |
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Silicon Detector, Low Noise Response, 5.1mm Sq
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NT54-522 | $51.00 |
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Silicon Detector, Low Noise Response, 100.0mm Sq
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NT57-513 | $130.00 |
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Silicon Detector, UV Enhanced Response, 0.8mm Sq
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NT57-509 | $39.00 |
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Silicon Detector, UV Enhanced Response, 5.1mm Sq
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NT53-375 | $49.00 |
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Silicon Detector, UV Enhanced Response, 15mm Sq
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NT57-510 | $50.00 |
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Silicon Detector, UV Enhanced Response, 20.0mm Sq
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NT54-036 | $47.00 |
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| Type of Reponse | Characteristics | Window Material | Applications |
| Normal | Biased, fast response time, low capacitance | Borosilicate | High light levels, pulse detectors, AC light measurement |
| UV/Blue Enhanced | Unbiased, high shunt resistance, low noise, long term stability | Quartz | Low light levels, wide spectral bandwidth response |
| Low Noise | Unbiased, low dark current, high shunt resistance | Borosilicate | Low light levels, long integration times |
| High Speed | Biased, low capacitance, >10MHz response | Borosilicate | Medium light levels, high pulse response detection |
| Terms | Definitions |
| Responsivity (R) | A measure of the effectiveness of a detector inp roducing an electrical signal. The product of the light input in Watts and the responsivity result in the predicted out-put of the detector in amps. Varies wth temperature. |
| Noise Equivalent Power (NEP) | The incident light power required to produce a signal on the detector that is equal to the noise. In this case, the signal to noise ratio is equal to one. |
| Detectivity (D) | D is a measure of the detecting ability of the photodiode. |
| Capacitance (C) | Also called the junction capacitance, is related to the rise time of the photodiode. The smaller the capacitance, the shorter the rise time, and vice versa. |
| Dark Current (Id) | The current associated with a detector during operation in the dark with an applied reverse bias. Increased temperature and reverse bias will result in increased dark current. Also, larger active areas will generally have a higher dark current. |
| Breakdown Voltage (BDV) | The voltage at which the detector begins to behave as a conductor. |
| Saturation Current (Isat) | Maximum level, above which the output current deviates 10% from linearity. |
| Shunt Resistance (Rsh) | Is the effective resistance of the photodiode. It represents the slope of the I-V curve at the origin (V=0). |
| Rise Time (TR) | The time necessary for a detectors output to go from 10% to 90% of its final value. |
| Biased: Normal Response (VBIAS = -10V) | ||||||||||
| Stock No. | Area (mm2) | R (A/W) @ 970nm |
NEP (with Hz1/2) @ -10V, 970nm |
D (cm*Hz1/2/W) @ -10V, 970nm |
C (pF) @ 0V |
C (pF) @ 10V |
Id (nA) @ 10V |
BDV max (V) |
TR (nsec) -10V/50O, 632nm |
Mount |
| #57-506 | 0.20 | 0.65 | 2.8 x 10-15 | 1.6 x 1013 | 4 | 1 | 0.01 | 30 | 6 | TO-18 |
| #57-507 | 0.81 | 0.65 | 6.2 x 10-15 | 1.45 x 1013 | 8 | 2 | 0.05 | 30 | 8 | TO-18 |
| #53-372 | 3.2** | 0.65 | 1.1 x 10-14 | 1.63 x 1013 | 45 | 12 | 0.15 | 30 | 10 | TO-18 |
| #53-371 | 5.1 | 0.65 | 1.4 x 10-14 | 1.61 x 1013 | 85 | 15 | 0.25 | 30 | 12 | TO-5 |
| #54-034 | 16.4 | 0.65 | 1.9 x 10-14 | 2.13 x 1013 | 330 | 60 | 0.5 | 30 | 17 | TO-8 |
| #54-035 | 44.0* | 0.65 | 2.8 x 10-14 | 2.37 x 1013 | 700 | 130 | 1 | 30 | 24 | TO-8 |
| #53-373 | 100.0 | 0.65 | 3.9 x 10-14 | 2.56 x 1013 | 1500 | 300 | 2 | 30 | 43 | BNC |
| #53-374 | 613.0 | 0.65 | 1.1 x 10-13 | 2.25 x 1013 | 9500 | 1800 | 15 | 30 | 250 | View |
*Square Sensor Size
**Rectangular Sensor Size
| Biased: High Speed Response (VBIAS = -50V) | ||||||||||
| Stock No. | Area (mm2) | R (A/W) @ 900nm |
NEP (with Hz1/2) @ -50V, 950nm |
D (cm*Hz1/2/W) @ -50V, 950nm |
C (pF) @ 0V |
C (pF) @ 50V |
Id (nA) @ 50V |
BDV (V) @ 10µA |
TR (nsec) 60V/50O, 670nm |
Mount |
| #57-512 | 0.85** | 0.62 | 4.8 x 10-14 | 1.9 x 1012 | 5.6 | 0.5 | 2 | 75 | 2 | View |
| #54-520 | 5.1 | 0.62 | 1.3 x 10-13 | 1.74 x 1012 | 28 | 3.5 | 12 | 75 | 2 | TO-5 |
| #55-338 | 15.0** | 0.62 | 2.0 x 10-13 | 1.94 x 1012 | 82 | 10 | 35 | 75 | 2 | TO-5 |
**Rectangular Sensor Size
| Unbiased: Blue Enhanced Response (VBIAS = OV) | |||||||||
| Stock No. | Area (mm2) | R (A/W) @ 410nm |
NEP (with Hz1/2) @ OV, 410nm |
D (cm*Hz1/2/W) @ OV, 410nm |
C (pF) @ 0V |
Isat max (mA) |
Rsh min (MO) |
TR (µsec) 0V/50O |
Mount |
| #57-508 | 0.81 | 0.2 | 2.0 x 10-14 | 4.5 x 1012 | 60 | 0.5 | 600 | 0.02 | TO-18 |
| #53-378 | 5.1 | 0.2 | 5.2 x 10-14 | 4.34 x 1012 | 450 | 2 | 150 | 0.2 | TO-5 |
| #53-379 | 100.0 | 0.2 | 2.0 x 10-13 | 5.0 x 1012 | 8800 | 10 | 10 | 2.0 | BNC |
| Biased: Low Noise Response (VBIAS = -5V) | ||||||||||
| Stock No. | Area (mm2) | R (A/W) @ 900nm |
NEP (with Hz1/2) @ -5V, 950nm |
D (cm*Hz1/2/W) @ -5V, 950nm |
C (pF) @ 0V |
C (pF) @ 5V |
Isat (mA) | Rsh min (MO) |
TR (nsec) 5V/50O, 670nm |
Mount |
| #54-522 | 5.1 | 0.62 | 1.8 x 10-14 | 1.25 x 1013 | 87 | 26 | 0.51 | 600 | 15 | TO-5 |
| #57-513 | 100.0* | 0.62 | 8.6 x 10-14 | 1.2 x 1013 | 1700 | 500 | 10.0 | 30 | 200 | View |
*Square Sensor Size
**Rectangular Sensor Size
| Unbiased: UV Enhanced Response (VBIAS = OV) | |||||||||
| Stock No. | Area (mm2) | R (A/W) @ 254nm |
NEP (with Hz1/2) @ 0V, 254nm |
D (cm*Hz1/2/W) @ 0V, 254nm |
C (pF) @ 0V |
Isat (mA) @ 10V |
Rsh (MO) @-10mV |
TR (µsec) 0V/50O, 254nm |
Mount |
| #57-509 | 0.8 | 0.14 | 6.4 x 10-14 | 1.4 x 1012 | 60 | 0.1 | 500 | 0.2 | TO-5 |
| #53-375 | 5.1 | 0.14 | 1.0 x 10-13 | 2.26 x 1012 | 300 | 0.1 | 200 | 0.9 | TO-5 |
| #57-510 | 15** | 0.14 | 1.4 x 10-13 | 2.8 x 1012 | 800 | 0.1 | 100 | 2.0 | TO-5 |
| #54-036 | 20.0 | 0.14 | 2.0 x 10-13 | 2.24 x 1012 | 1000 | 0.1 | 50 | 2.0 | TO-8 |
| #54-037 | 35.0** | 0.14 | 1.7 x 10-13 | 3.48 x 1012 | 1600 | 0.1 | 30 | 3.0 | TO-8 |
| #53-376 | 50.0 | 0.14 | 2.6 x 10-13 | 2.72 x 1012 | 2500 | 0.1 | 20 | 3.5 | BNC |
| #53-377 | 100.0 | 0.14 | 4.5 x 10-13 | 2.22 x 1012 | 4500 | 0.1 | 10 | 5.9 | BNC |
