Photomultiplier tube module


The H15461-40-01 is a photomultiplier tube module with BNC connector that employs a GaAsP photocathode photomultiplier tube. The photosensitive area is 14 mm square making it ideal for multiphoton excitation microscopes. 

Application examples

Multiphoton microscopy

Multiphoton microscopy is a technique for observing fluorescence in the UV to visible region that occurs when fluorescent molecules are excited by simultaneously absorbing two photons.
The wavelength of the excitation light in common fluorescence measurement is shorter than the fluorescence wavelength. However, multiphoton spectroscopy uses excitation light in the near-infrared region, which has a wavelength longer than the fluorescence wavelength. Since near-infrared light passes more easily through an object than visible light does, it can provide information on deep portions within an object and also reduces effects from scattering and background noise inside the object. Furthermore, the energy of near-infrared light is lower than that of visible and UV light, thus minimizing damage to cells.

How it differs from single-photon excitation microscopy

Laser scanning microscopy

Imaging example: Deep mouse brain imaging

Microscope that captures the ‘universe’ in a mouse’s brain (video courtesy of Dr. Masanori Murayama, RIKEN Center for Brain Science in Japan)

This video shows the activity of more than 6000 single neurons in the fifth layer of the mouse cerebral cortex located at a depth approximately 500 μm from the brain surface. This video was captured with a microscope using the H15460-40 photosensor module and dedicated optical system. The wide photosensitive area and high sensitivity offered by the H15460-40 provide observations with wide field-of-view and high resolution. 

Wide field-of-view

Up until now, the field-of-view observable with a two-photon microscope was limited to an extremely small area of about 0.25 mm2. This very narrow field-of-view prevented simultaneously viewing nerve cells in multiple brain regions even in small animals such as mice.

To make this measurement with a wider field-of-view, the H15460-40 photosensor module having a large effective area is used in combination with a uniquely designed optical system. This setup allows observing cell activities in a field-of-view that is 36 times larger than conventional two-photon microscopes.

Deep observation

Observing cell activities with high time resolution usually requires high-speed laser scanning. However, increasing the laser scan speed reduces the laser stay time over the sample, making it difficult to capture images with a high signal-to-noise ratio. The fluorescence intensity also drops significantly especially when imaging deep within the sample.

To cope with this problem and capture more fluorescence, the H15460-40 photosensor module with its high sensitivity and a wide photosensitive area is used in combination with a uniquely designed optical system. This allows capturing even more fluorescence that could not be detected up until now, so that images with a high signal-to-noise ratio can be captured even when making observations deep within the sample.

Effective area


Photocathode Area Shape Square
Photocathode Area Size 14 mm x 14 mm
Wavelength (Short) 300 nm
Wavelength (Long) 740 nm
Wavelength (Peak) 520 nm
Dimension (W x H x D) 38 mm x 38 mm x 55 mm
Input Voltage +4.5 to +5.5 V
Max. Input Voltage +5.5 V
Max. Input Current +3.5 mA
Max. Output Signal Current 100 µA
Max. Control Voltage +1.1 V
Recommended Control Voltage Adjustment Range +0.5 to +1.0 V
[Cathode] Radiant Sensitivity Typ. 189 mA/W
[Cathode] Luminous Sensitivity Typ. 850 μA/lm
[Anode] Radiant Sensitivity Typ. 3.8 x 105 A/W
[Anode] Luminous Sensitivity Typ. 1.7 x 103 A/lm
[Anode] Dark Current Typ. 10 nA
[Anode] Dark Current Max. 50 nA
[Time Response] Rise Time Typ. 1.1 ns
Ripple Noise (peak to peak) Max. 0.2 mV
Settling Time Max. 10 s
Operating Ambient Temperature +5 to +50 ℃
Storage Temperature -20 to +50 ℃
Weight 105 g

Dimensional outline (Unit: mm)

*H15461-40-01: with BNC-P plug connector

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