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PRM-400 Dual Precision Ratemeter ⁄ Photon Counter

The Ultimate in Photon Counting and The Fastest Photon Counter available on the market!


  • Fast Counter/Timer Ratemeter (400MHz)
  • Counts Every Pulse. No Prescaling!
  • 10 µs Shortest Time Base
  • Dual Counter for Background Subtraction
  • Large FIFO Data Storage
  • Zero Dead Time (Alternating Counters)
  • Large 40 Bit Deep Counters
  • Gated Inputs
  • Accepts Standard TTL,NIM,ECL Inputs
  • Digital/Bar Graph Intelligent LCD Display
  • Parallel, Serial, GPIB Computer Interface
  • Easy Computer Interfacing. No Plug-in Boards!
  • Versatile. Easy to Use
  • Analog Output
  • Size: 4x14x9 inches
Ari corp
Ari corp

PRM-400 Dual Precision Counter/Timer

A dual counter/timer data acquisition system capable of operating at speeds over 500 MHz the PRM-400 can be used in a zero dead time mode with the two counters alternating. With this back to back counting there is no loss of counts.

PRM-400 Dual Precision Counter/Timer
Max. Repetition Rate > 400MHz
Pulse Pair Resolution < 2 ns
Each Counter Depth 40 Bits (1012 Counts)
Display 40x2 Characters Back Lighted LCD
Data Displayed Ch A, Ch B, A+B, A-B, A/B, CPS, Hz, Counts
Bar Graph Display 100 to 108, Manual or Auto-range
Analog Output Data Follows the Bar Graph Display
Time Base 10 µs, 100 µs, 1ms, 10 ms, 100 ms, 1s, 10s
TTL Inputs Standard BNC, 100 Ohm Termination
ECL Inputs Twin BNC, 50 Ohms to -2 Volts.
NIM Inputs Standard BNC, 50 Ohm Termination
Preamplifier Inputs 9 Pin Mini D for ARI Preamplifiers
Digital Outputs Parallel (Printer Port), RS-232, GPIB
Analog Outputs BNC, 0 to +2VDC
Power Requirements 120 VAC or 220 VAC (specify when ordering)


Ari corp
Ari corp

Typical photon counting with background subtraction

Select CH.A ? CH.B display for the background subtraction. A TTL inhibit signal will block off undesirable incoming pulses, if any, and hold off the timer for correct counts per second value.

Unique photon counting in zero dead time mode

Here only one counter is counting for the preset time. When the timer reaches the preset time the second counter instantaneously starts counting. No counts will be lost. While the second counter is counting the data from the first counter are transferred to a FIFO and the counter is reset to zero. Now the first counter is ready to start counting again when the preset time runs out so that one of the counters is always counting. A TTL inhibit signal will block off undesirable incoming pulses, if any, and hold off the timer for correct counts per second value.

Ari corp

Background subtraction with a single PMT

In this configuration the signal is interrupted at 50% of the time by light chopper. The signal is applied to both inputs. By inhibiting the A counter during the black-out period by setting inhibit A to ?Inh. on L? the A counter will count the signal plus the background only during the period the chopper allows the signal through. When the light passes through the chopper, the inhibits are high. The A counter is counting the signal and the clock is running. The counter B is inhibited. During the next period, the black-out period, the counter A is inhibited and the counter B is enabled. The optical signal is blocked by the chopper and the B counter is counting the background. By selecting the display to show A-B value, we are subtracting the dark current count as well as other scattered light signal. To test this configuration, you only need to block the light signal before the chopper and the A-B display should read zero within the expected statistical fluctuation.


in US dollars
  Domestic International
PRM-400 $4,900.00 $6,125.00

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