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High-speed gated image intensifier units (hereafter gated I.I. units) are able to capture an "instantaneous image" of high-speed phenomena oc- curring within extremely short time durations by means of "gate operation (shutter operation)". Gate operation is basically the same function as a camera shutter, but gated I.I. units perform this operation electronically in a minimum gate time of 1/300 000 000th of a second. Another feature is that background light and excitation light outside the measurement time can be eliminated by synchronizing the gate opera- tion with a laser pulse or other signal.
Gated I.I. units have an internal image enhancement function that al- lows visualizing low-level light images invisible to the human eye. As the gate time becomes faster, less light is available so this image enhancement function is essential for gate operation. Image enhancement is achieved by the built-in MCP (microchannel plate) which is available in 1-stage and 2-stage types to meet application needs.
Image intensifiers used in gated I.I. units cover a wide spectral range to allow imaging at desired wavelengths over a broad range from the UV to infrared.
Use the following guidelines to select a high-speed gated image intensifier unit having features and specifications ideal for your measurements. The six items listed below are very important for selecting the right product. Select the product you need by using a combination of these six items.
Item | Description | Selection Method | |
---|---|---|---|
Image Intensifier (I.I.) | Photocathode sensitivity | The higher the quantum efficiency (conversion efficien- cy from input light into photoelectrons), the smaller the flicker that appears in the obtained image. It is important to select the photocathode with spectral response that matches the emission wavelengths to be measured. |
What is the spectral range to be detected. -UV to near IR range Use a multialkali photocathode. -Near IR range Use a GaAs photocathode. -Visible range Use a GaAsP photocathode |
Stage of MCPs | This is the factor which determines the image intensifi- cation level and the resulting detection limit. With ordi- nary CCD cameras, the limit for imaging is around 0.1 lux. The intensifier unit may have either a 1-stage or a 2-stage MCP. With the 1-stage MCP type, the image is enhanced around 10,000 times, enabling images to be captured at low-light-levels of 1 10-5 lux. With the 2- stage MCP type, images are enhanced approximately one million times, and can be captured at even lower light levels of 1 10-7 lux. The 2-stage MCP type offers sensitivity that enables detection at single-photon level. The light levels noted above are for a gate time of 1 second. The relative quantity of light decreases as the gate time shortens, so it is necessary to increase the quantity of incident light. |
●Single molecule fluorescence imaging .... 2-MCP type When monitoring candlelight: ●Gate time: less than 1 ..... 2-MCP type more than 5 ... 1-MCP type The above numeric values are general guides, and are affected by conditions such as the light level, gate time, image intensification (gain), lens, imaging device, and other factors. Please consult Hamamatsu regarding details. |
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Effective output size | This is the factor which determines the resolution. The size of the effective input surface is determined by the desired resolution* of the output image and the size of the incident image. The image resolution de- grades as the quantity of incident light decreases. | ||
Gate | Gate time | This is the time required to capture one image. “Instantaneous images” of phenomena occurring within this gate time can be captured. If the gate time is short- ened, images with little movement can still be captured, but there is less light, so that a darker image results. (A unit with a gate time appropriate for the measurement target should be selected.) | Select the disired gate time according to the time period during which im- ages are to be captured. |
Gate repetition frequency | This is the number of gate operations in 1 second. This also depends on the repetition frequency of the object being meas- ured and the number of frames of the camera being used. | Select the disired gate time according to the time period during which im- ages are to be captured. | |
Frame rate of readout camera | This is the factor determining whether or not an image booster is required. As the camera frame rate is increased, the output light level only from the proximity focused image intensifier becomes too low to acquire images with enough brightness. An image booster is required in this case to obtain a higher output light level. |
Camera frame rate • 1000 frames/second or more: A booster is required. Select the C10880 series. • 300 to 1000 frames/second: Use of a booster and the C10880 series is recommended. |
Type No. |
⑴ Photo- cathode |
⑵ Spectral Response (nm) |
Input / Output Area (mm) | Phosphor Screen / Output Window | Stage of MCPs |
⑻ Luminous Gain (lm/m2)/lx Typ. |
⑻ EBI Radiant (W/cm2) Typ. |
⑻ Limiting Resolution (Lp/mm) Typ. |
Gate Time | Maximum Repetition Frequency (kHz) |
PC Control |
Power Supply | Operating Ambient Temperature / Humidity |
⑶ Dimen- sions No. |
C9016-01 | GaAsP | 280 to 720 | 17 ⑷ | P43 / FOP | 1 | 2.2x104 | 8.0 ´ 10-15 | 64 | 10 ms to 100 ms | 0.2 | USB |
USB ⑹ ro AC100 V to 240 V ⑺ |
0 °C to +40 °C / Less than 70 % (No condensation) |
① |
C9016-02 | 2 | 5.0x106 | 40 | |||||||||||
C9016-03 | Multialkali | 185 to 900 | 1 | 1.2x104 | 3.0 ´ 10-14 | 64 | ||||||||
C9016-04 | 2 | 5.0x106 | 32 | |||||||||||
C9016-05 | GaAs | 370 to 920 | 1 | 4.0x104 | 4.0 ´ 10-14 | 64 | ||||||||
C9016-06 | 2 | 9.6x106 | 40 | |||||||||||
C9016-21 | GaAsP | 280 to 720 | 17 ⑷ | P43 / FOP | 1 | 2.2x104 | 8.0x10-15 | 64 | 20 ns to DC | 2 | USB | AC100 V to 240 V ⑺ | ① | |
C9016-22 | 2 | 5.0x106 | 40 | |||||||||||
C9016-23 | Multialkali | 185 to 900 | 1 | 1.1x104 | 3.0x10-14 | 64 | ||||||||
C9016-24 | 2 | 4.0x106 | 32 | |||||||||||
C9016-25 | GaAs | 370 to 920 | 1 | 4.0x104 | 4.0x10-14 | 64 | ||||||||
C9016-26 | 2 | 9.6x106 | 40 | |||||||||||
C9546-01 | GaAsP | 280 to 720 | 17 ⑷ | P43 / FOP | 1 | 2.0x104 | 8.0x10-15 | 64 | 3 ns to DC | 30 | USB | AC100 V to 240 V ⑺ | ② | |
C9546-02 | 2 | 3.0x106 | 40 | |||||||||||
C9546-03 | Multialkali | 185 to 900 | 1 | 1.0x104 | 3.0x10-14 | 64 | ||||||||
C9546-04 | 2 | 2.4x106 | 32 | |||||||||||
C9546-05 | GaAs | 370 to 920 | 1 | 3.6x104 | 4.0x10-14 | 64 | ||||||||
C9546-06 | 2 | 5.8x106 | 40 | |||||||||||
C9547-01 | GaAsP | 280 to 720 | 25 ⑸ | P43 / FOP | 1 | 1.8x104 | 8.0x10-15 | 50 | 5 ns to DC | 30 | USB | AC100 V to 240 V ⑺ | ③ | |
C9547-02 | 2 | 3.0x106 | 32 | |||||||||||
C9547-03 | Multialkali | 185 to 900 | 1 | 1.0x104 | 3.0x10-14 | 64 | 10 ns to DC | |||||||
C9547-04 | 2 | 2.4x106 | 32 | |||||||||||
C9547-05 | GaAs | 370 to 920 | 1 | 3.0x104 | 4.0x10-14 | 50 | 5 ns to DC | |||||||
C9547-06 | 2 | 5.3x106 | 32 | |||||||||||
C9548-01 | GaAsP | 280 to 720 | 25 ⑸ | P46 / FOP | 1 | 6.6x103 | 2.0x10-14 | 45 | 10 ns to 9.99 ms | 200 | RS-232C | AC100 V to 240 V ⑺ | ④ | |
C9548-02 | 2 | 1.5x106 | 32 | |||||||||||
C9548-03 | Multialkali | 185 to 900 | 1 | 3.3x103 | 3.0x10-14 | 57 | ||||||||
C9548-04 | 2 | 1.0x106 | 28 | |||||||||||
C9548-05 | GaAs | 370 to 920 | 1 | 9.9x103 | 4.0x10-14 | 45 | ||||||||
C9548-06 | 2 | 2.6x106 | 28 |
●High-speed Gated Image Intensifier Unit for High-speed Camera
Type No. (Input mount) |
⑴ Photo- cathode |
⑵ Spectral Response (nm) |
Input / Output Area (mm) | Phosphor Screen / Output Window | Stage of MCPs |
⑻ Luminous Gain (lm/m2)/lx Typ. |
⑻ EBI Radiant (W/cm2) Typ. |
⑻ Limiting Resolution (Lp/mm) Typ. |
Gate Time | Maximum Repetition Frequency (kHz) |
PC Control |
Power Supply | Operating Ambient Temperature / Humidity |
⑶ Dimen- sions No. |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
C10880-03C (C-Mount) |
Multialkali | 185 to 900 |
24 / 16 |
P46 + P46 / Borosiricate glass |
1 | 1.0x105 | 2x10-9 | 38 | 10 ns to 9.99 ms | 200 | RS-232C | AC100 V to 240 V ⑺ |
0 °C to +40 °C / Less than 70 % (No condensation) |
⑤ |
C10880-03F (F-Mount) |
⑥ |
This makes it easy to replace the relay lens with one of a different magnification, or to attach the lens to a different camera. The transmission efficiency is not as high as that of fiber coupling, however, and the optics system as a whole is less compact.
The output image from the gated I.I. unit is transferred directly to the CCD with a fiber coupling, for highly efficient readout. Higher efficiency means that the quantity of incident light can be suppressed, which in turn extends the lifetime of the image intensifier. In addition, a more compact optics system can be used. The only drawback to this construction is that the readout system is difficult to replace.
The C10054 series have internal fiber coupling.
The FOP is an optical device consisting of millions of glass fibers of 6 micrometers in diameter, bundled parallel to one another.
Since light is transmitted through each fiber, an image can be transferred from one end of the fiber to the other without any distorion. FOPs are widely used as optical devices that replace optical lens.
The C9018 series CCD cameras have a restart / reset function and are designed to read out images from C9016 and C9546 series image intensifier units. Fiber coupling allows more highly efficient image readout than lens coupling.
The ORCA-Flash4.0 V2 is a sophisticated camera using a CMOS image sensor designed for scientific measurement. Coupling this camera to a high-speed gated image intensifier unit of the C9016 series or C9546 series or C9547 series via a relay lens allows high-speed image readout with even higher sensitivity and resolution.
● High quantum efficiency: 70 % or more (at 600 nm wavelength)
● Low noise: 1.3 electrons median (at 100 frames per second)
● High resolution: 4 million pixels (6.5 x 6.5 image format)
● High-speed readout: 100 frames per second
The photo shows the C9546 series connected to the ORCA-Flash4.0 V2 digital camera via a relay lens adapter A9017, and relay lens A11669. The output surface of the image intensifier is projected onto the input surface of the digital camera with a reduction ratio of 2/3.
The effective imaging area of the C9016 and C9546 series when used with a relay lens A4539 is as follows:
(1) Image intensifier output surface (photocathode) size : 17 mm diameter
(2) Effective area of the ORCA-Flash4.0 V2 digital camera : 13.3 mm x 13.3 mm
(3) Effective photocathode area of the image intensifier : 13.5 mm x 10 mm
The product catalog for the ORCA-Flash4.0 V2 digital camera is available. Feel free to contact us or access our website to download it.
The C10054 series is a family of high sensitivity cameras that integrate a proximity type image intensifier with a CCD camera for readout, which are coupled by a fiber optic plate. The image intensifier operates with a high- speed electronic shutter to perform high-speed imaging.
●Photocathode: GaAsP, GaAs, multialkali
●Shutter time: 5 ns to DC
●Maximum shutter repetition rate: 2 kHz
●Signal format: EIA, CCIR, full pixel readout
This is what pulsed laser light passing through an optical fiber looks like when observed with a high-speed gated image intensifier. This allows verifying the distance that the light pulse travels after emission per the gate time.
* Unsheathed optical fiber was used to observe light pulse from external side.
* Optical fiber refractive index: 1.5
Image at 3 ns gate time: Image shows light moved 60 cm.
Image at 100 ns gate time: Light has moved 20 m, so entire fiber is emitting light.
Pulsed laser light is guided into the fiber optic cable wound around a glass pipe. A high-speed gated image intensifier is used to capture an image of pulsed light passing through to optical fiber optic. The image cap- tured with the gated image intensifier is then read out with a camera.
To control the gate time (shutter speed), pulsed light is split by a beamsplitting mirror into two paths. A PIN photodiode detects light on one path and generates a trigger signal for input to a pulse generator. This pulse generator provides a TTL signal output for the high-speed gated image intensifier power supply.
The image intensifier unit allows observing weak fluorescence emitted from cells. The images below show the process by which nuclear fission progresses in aspergillus oryzae stained with GFP. These images were viewed through a fluorescence microscope and confocal unit and were taken with an AP Imager Camera after being optically amplified by the C9016-01 image intensifier unit.
These images clearly show that the number of cells increased during nuclear division occurring in the up- ward direction on the images.
Using an image intensifier unit allows observing these cellular activities with minimum laser input power. This prevents damaging the cells under observation.
The cells under observation are irradiated with a laser beam and the resulting fluorescence then observed through a fluorescence microscope and confocal unit. After being amplified by the C9016-01 image intensifi- er unit, the fluorescence image is then read out by the high-resolution AP Imager Camera that produces almost no signal multiplication noise.
The degree of soot clouds produced in a diesel flame was monitored using the laser sheet method and a gated I.I. unit. Using the gated I.I. unit, it was possible to measure faint scattered light at high sensitivity. Also, by using gating at a high repetition rate, it was possible to capture kinetic changes in the amount of soot being produced. Images of the flame taken directly with a high-speed camera were compared with simultaneous photographs of the scattered image, enabling changes in the degree of soot being produced from the diesel combustion to be observed over time, and showing the relationship between soot conditions and the flame.
Scattered soot image (photographed with high-speed gated image intensifier unit)
ATDC: After top dead center TDC: Top dead center
: Crank angle based on ATDC as reference
The YAG laser is directed into a sheet configuration and the interior of the combustion chamber is irradiated with the laser sheet. Scattered light from the soot particles is detected using the gated I.I. unit. The gate operation of the gated I.I. unit is synchronized to the light source, enabling moving images of the scattered light to be captured. To further clarify the flame conditions, a half-mirror is introduced and the direct flame image captured with a high- speed camera.
Photo and information: Courtesy of professer M. Shioji from Kyoto University.
REFERENCES
* M. Shioji, et al.: 1992 JSAE Autumn Convention Proceedings, 924, 41-44(1992). (Published in Japanese)
Changes in a micro-discharge phenomenon were observed by connecting a gated image intensifier unit to a high-speed camera that captures images at 500,000 frames per second.
Capturing a high-speed phenomenon at faint light emissions is usually impossible with a camera operating at a low frame rate, because low frame rates do not provide enough time resolution. However, merely in- creasing the frame rate (less exposure time) reduces the input light level and makes the acquired images darker and unsatisfactory. We succeeded in capturing clear images of very weak light emission at a high frame rate by combining a high-speed camera with a high-speed gated image intensifier unit that contains a proximity focused image intensifier coupled to an inverter type intensifier and provides high brightness output.
The camera is synchronized based on a trigger signal generated just prior to a discharge phenomenon, and the trigger signal is input to the gated image intensifier unit so that the gate opens only during the time the discharge phenomenon occurs.
ICCD cameras are ideal for observing the low-level light emitted (sonoluminescence) when cavitations occur in ultrasonic washers.
The image on the left shows a boat sailing at sea on a rainy night captured with the ICCD camera and a laser. The boast is clearly visible due to use of a near infrared laser and high-speed gating of the image intensifier. The image on the right captured with a floodlight camera is not clear since the illuminating light reflects off the raindrops.
The data below shows the results from time-resolved photoluminescence imaging (TRI) measured when a polycrystalline silicon wafer was irradiated with light at different excitation frequencies having an intensity of 2.5 x 1017/cm2•s. The silicon wafer is 5 5 cm in size and 200 m in thickness and both sides are passivated with SiNx. This proves that uncertainty is drastically improved (s(teff) for [d] was improved by 10 % compared to [c]) by increasing the excitation frequency.
Light from an LED or laser is irradiated onto the polycrys- talline silicon wafer to cause photoluminescence which is then focused on the image intensifier via the objective lens. Photons generated by photoluminescence in the sil- icon wafer are multiplied in the image intensifier and the visible image output from the image intensifier is focused on the CCD image sensor via the relay lens.