Fax: (765) 423-4111 . www.lafayetteinstrument.com . [email protected]
Model 12021A User Instructions
Overview
The Model 12021A Flicker Fusion is designed to test for the critical flicker fusion threshold (CFF). CFF can be used
as an index of the temporal resolving power of the human visual system. The threshold of the flicker fusion is
determined in the following manner: a light beam is interrupted intermittently by electronic means at a slow
rate, causing it to flash or flicker. If the rate of the flicker exceeds a certain rate, the light will appear steady. The
rate at which flicker ceases and the light appears steady is the threshold of fusion. The rate of flicker is then
decreased from steady to the point at which the light changes from steady to flicker, the threshold flicker. The
average of the threshold of fusion and the threshold of flicker is called the critical flicker fusion threshold (CFF).
CFF is sensitive to a number of presentation and observer variables. Presentation variables include stimulus
frequency, luminance of the stimulus, stimulus size, light/dark ration, stimulus color, and contrast. Observer
variables reported to affect results include body temperature, practice, general physiological state, age, sex,
and genetic variables.
Specifications
Power Supply:
10 VDC @ 1.5A, 2.1mm center positive DC plug
Fuse:
0.5A 5 x 20mm fast blow
Frequency:
1.0 to 100.0 Hz in 0.1 Hz increments with an error of 0.05%
Slide Holder:
2” x 2” 35mm holder for optional 12100 neutral density filters with 0.1% to 50% light transmission
Auto Mode Ramp Rates:
options of 0.5, 1, 2, and 4 Hz per second
Analog Input:
3.5mm mono phone plug with voltage range from 0.1 to 10V for 1.0 to 100.0 Hz flicker rate;
ABSOLUTE MAXIMUM INPUT = 14V
External Initiate:
SPST normally open hand-held switch with RCA input
External Response:
SPST normally open hand-held switch with 3.5mm stereo plug
RS-232C Port Settings:
9600 baud, no parity, 8 data bits, 1 stop bit
Typical Maximum Luminance:
58 Cd/m
2
Viewing Angle:
1.9
o
Light/Dark Ratio:
1:1
Stimulus Color:
White
Viewing Chamber Mask:
hypo-allergenic black silicone; mask may be cleaned with an alcohol wipe
Control Size:
8 5/8”W x 6.5”L x 3 ¼”H; Weight 1.8 lbs
Viewing Chamber Size:
7”W x 19”L x 16”H; Weight 7.4 lbs
Parts Included
•
1 – Control Unit
•
1 – Viewing Chamber
•
1 – 10 VDC wall mount AC adapter
•
1 – DB9 Female to Female cable
•
1 – DB15 Male to Female cable
•
1 – Single hand-held push button
•
1 – Dual hand-held push button
3