Photometer
 When you need to perform microscope photometry, what do you use? Most labs end up acquiring some microscope accessory intended for another purpose—such as photography.
Unfortunately, these devices are rarely up for the task. Microscope photometry requires absolute light-tightness. It also helps to have a device designed to accommodate a photomultiplier housing—or even two. Additionally, it should hold filters, have an adjustable iris, and provide a means to view the image being measured.
Microscope photometers from PTI do all of this—and more. They are specifically designed for sensitive photometric measurements. And they couple easily to virtually any popular microscope.
 The Model D-104B is a single-channel photometer. The D-104C is a dual-channel photometer that allows simultaneous measurements at two different wavelengths via a dichroic cube.
No system is complete without an analog/digital photon counting detector
In order to complete a Ratiomaster
system, an analog/digital photon counting
detector, selected from only our best
quality and performing photo-multipliers,
the 814 series. You may also select one of
the excellent Red sensitive PMT's to complement
the system.
Analog/Digital Photon Counting
 Model 814 is a compact PMT housing
for analog or digital (photon-counting)
detection. The detection mode is
switchable, and the built-in LCD can also
selectively display high voltage or analog
signal level.
Features power on/off switch, high
voltage adjust, LCD high voltage/analog
signal display, detection mode and display
mode switches, gain, time constant and
offset adjustment controls, BNC signal
output connection, BNC external high voltage
adjust input connection, light-tight RF shielded case, internal direct anode output
mode control, and socket for most 1-1/8
inch side-on photomultiplier tubes. Includes
a separate wall-mount line voltage
power supply. This detection system excels
at applications like the following:
- Live-cell imaging
- High-speed emission ratio imaging
- Quantitative FRET, FRAP, FISH
- Luminescence
Analog Mode:
This mode can
be used for medium to high levels of
light intensity. The maximum PMT current
is 10 microamperes. The output is a
DC signal between +13 Volts and -13
Volts.
Photon-Counting (Digital) Mode:
This mode can be used for low
to medium light levels up to 4 million
counts per second. The output is a TTL
level, active low signal. The signal line
must be terminated at 50 ohms. The
output is a frequency corresponding to
the number of photons impinging on
the photocathode.
Digital Photometer Specifications
| Maximum count rate |
4 MHz |
|
| Pulse pair resolution |
250 ns |
|
| Output |
TTL level active low pulse |
|
| Rise time |
20 ns |
|
| Fall time |
100 ns |
|
| Pulse width |
220 ns |
|
