摘要 |
<p>The invention provides devices and methods for electronically simulating a standard absorbance value in an analytical instrument that measures absorbance of light in order to verify the correct operation of the instrument. A liquid-crystal/polarizing-filter combination located in the light pathway normally occupied by sample is used, along with sufficient voltage changes to selectively block and transmit light through the liquid crystal, thereby causing a light detector in the analytical instrument to read transmitted and blocked values of light. A calculation then is used to determine whether proper operation of the instrument has occurred. Different absorbance values, as well as different patterns of varying transmission (such as exponential decay), can be simulated by causing the liquid crystal to switch from absorbance to transmission (or vice versa) at different times.</p> |