# Example 24: corr_irr2 - generic irradiance and PAR

This equation is a refined and simplified version of the one given in Example 23, and will typically be used to present irradiance in μW/cm^{2}/nm, or PAR in μmol/m²/s.

Then applies a linear equation to convert to final units:

where

**c0**is a user-adjustable dark offset value,**c1**is the primary slope coefficient which transforms the value to final units,**c2**is an immersion factor, which corrects for use in a medium other than was used for calibration; water compared with air, for example,**R**is the raw voltage ratio measured by the logger,**x0**,**x1, x2**are factory-determined coefficients of a quadratic term, used to correct the sensor's dark current for temperature effects,**x3**is the temperature at which the optical calibration was performed,*T*is the internally measured temperature of the sensor in °C, and_{sensor}*Irr*is the final value of irradiance or PAR, temperature compensated and presented in final calibration units._{tempcompensated}

## Examples

```
>> channel 3 type
<< channel 3 type = irr_05
```

Confirm the channel type.

`>> calibration 3 datetime = 20210901085500, c0 = 0.000, c1 = 5079.0, c2 = 1.2`

Set the core coefficients.

```
>> calibration 3
<< calibration 3 label = irradiance_00, datetime = 20210901085500, c0 = 0.000, c1 = 5079.0, c2 = 1.2, x0 = 0.098, x1 = 0.023, x2 = 0.00037, x3 = 23.4, n0 = 4
```

Request confirmation of all calibration coefficients.